Regenerate the test files and add the fstar-split tests

70 files changed, 11726 insertions, 3238 deletions

diff --git a/tests/fstar-split/array/Array.Clauses.Template.fst b/tests/fstar-split/array/Array.Clauses.Template.fst
new file mode 100644
index 00000000..b2f2649c
--- /dev/null
+++ b/tests/fstar-split/array/Array.Clauses.Template.fst
@@ -0,0 +1,21 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [array]: templates for the decreases clauses *)
+module Array.Clauses.Template
+open Primitives
+open Array.Types
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [array::sum]: decreases clause
+    Source: 'src/array.rs', lines 242:0-250:1 *)
+unfold
+let sum_loop_decreases (s : slice u32) (sum1 : u32) (i : usize) : nat =
+  admit ()
+
+(** [array::sum2]: decreases clause
+    Source: 'src/array.rs', lines 252:0-261:1 *)
+unfold
+let sum2_loop_decreases (s : slice u32) (s2 : slice u32) (sum1 : u32)
+  (i : usize) : nat =
+  admit ()
+
diff --git a/tests/fstar-split/array/Array.Clauses.fst b/tests/fstar-split/array/Array.Clauses.fst
new file mode 100644
index 00000000..68cbf216
--- /dev/null
+++ b/tests/fstar-split/array/Array.Clauses.fst
@@ -0,0 +1,19 @@
+(** [array]: decreases clauses *)
+module Array.Clauses
+open Primitives
+open Array.Types
+open FStar.List.Tot
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [array::sum]: decreases clause *)
+unfold
+let sum_loop_decreases (s : slice u32) (sum : u32) (i : usize) : nat =
+  if i < length s then length s - i else 0
+
+(** [array::sum2]: decreases clause *)
+unfold
+let sum2_loop_decreases (s : slice u32) (s2 : slice u32) (sum : u32)
+  (i : usize) : nat =
+  if i < length s then length s - i else 0
+
diff --git a/tests/fstar-split/array/Array.Funs.fst b/tests/fstar-split/array/Array.Funs.fst
new file mode 100644
index 00000000..30b19702
--- /dev/null
+++ b/tests/fstar-split/array/Array.Funs.fst
@@ -0,0 +1,445 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [array]: function definitions *)
+module Array.Funs
+open Primitives
+include Array.Types
+include Array.Clauses
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [array::incr]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/array.rs', lines 8:0-8:24 *)
+let incr (x : u32) : result u32 =
+  u32_add x 1
+
+(** [array::array_to_shared_slice_]: forward function
+    Source: 'src/array.rs', lines 16:0-16:53 *)
+let array_to_shared_slice_ (t : Type0) (s : array t 32) : result (slice t) =
+  array_to_slice t 32 s
+
+(** [array::array_to_mut_slice_]: forward function
+    Source: 'src/array.rs', lines 21:0-21:58 *)
+let array_to_mut_slice_ (t : Type0) (s : array t 32) : result (slice t) =
+  array_to_slice t 32 s
+
+(** [array::array_to_mut_slice_]: backward function 0
+    Source: 'src/array.rs', lines 21:0-21:58 *)
+let array_to_mut_slice__back
+  (t : Type0) (s : array t 32) (ret : slice t) : result (array t 32) =
+  array_from_slice t 32 s ret
+
+(** [array::array_len]: forward function
+    Source: 'src/array.rs', lines 25:0-25:40 *)
+let array_len (t : Type0) (s : array t 32) : result usize =
+  let* s1 = array_to_slice t 32 s in let i = slice_len t s1 in Return i
+
+(** [array::shared_array_len]: forward function
+    Source: 'src/array.rs', lines 29:0-29:48 *)
+let shared_array_len (t : Type0) (s : array t 32) : result usize =
+  let* s1 = array_to_slice t 32 s in let i = slice_len t s1 in Return i
+
+(** [array::shared_slice_len]: forward function
+    Source: 'src/array.rs', lines 33:0-33:44 *)
+let shared_slice_len (t : Type0) (s : slice t) : result usize =
+  let i = slice_len t s in Return i
+
+(** [array::index_array_shared]: forward function
+    Source: 'src/array.rs', lines 37:0-37:57 *)
+let index_array_shared (t : Type0) (s : array t 32) (i : usize) : result t =
+  array_index_usize t 32 s i
+
+(** [array::index_array_u32]: forward function
+    Source: 'src/array.rs', lines 44:0-44:53 *)
+let index_array_u32 (s : array u32 32) (i : usize) : result u32 =
+  array_index_usize u32 32 s i
+
+(** [array::index_array_copy]: forward function
+    Source: 'src/array.rs', lines 48:0-48:45 *)
+let index_array_copy (x : array u32 32) : result u32 =
+  array_index_usize u32 32 x 0
+
+(** [array::index_mut_array]: forward function
+    Source: 'src/array.rs', lines 52:0-52:62 *)
+let index_mut_array (t : Type0) (s : array t 32) (i : usize) : result t =
+  array_index_usize t 32 s i
+
+(** [array::index_mut_array]: backward function 0
+    Source: 'src/array.rs', lines 52:0-52:62 *)
+let index_mut_array_back
+  (t : Type0) (s : array t 32) (i : usize) (ret : t) : result (array t 32) =
+  array_update_usize t 32 s i ret
+
+(** [array::index_slice]: forward function
+    Source: 'src/array.rs', lines 56:0-56:46 *)
+let index_slice (t : Type0) (s : slice t) (i : usize) : result t =
+  slice_index_usize t s i
+
+(** [array::index_mut_slice]: forward function
+    Source: 'src/array.rs', lines 60:0-60:58 *)
+let index_mut_slice (t : Type0) (s : slice t) (i : usize) : result t =
+  slice_index_usize t s i
+
+(** [array::index_mut_slice]: backward function 0
+    Source: 'src/array.rs', lines 60:0-60:58 *)
+let index_mut_slice_back
+  (t : Type0) (s : slice t) (i : usize) (ret : t) : result (slice t) =
+  slice_update_usize t s i ret
+
+(** [array::slice_subslice_shared_]: forward function
+    Source: 'src/array.rs', lines 64:0-64:70 *)
+let slice_subslice_shared_
+  (x : slice u32) (y : usize) (z : usize) : result (slice u32) =
+  core_slice_index_Slice_index u32 (core_ops_range_Range usize)
+    (core_slice_index_SliceIndexRangeUsizeSliceTInst u32) x
+    { start = y; end_ = z }
+
+(** [array::slice_subslice_mut_]: forward function
+    Source: 'src/array.rs', lines 68:0-68:75 *)
+let slice_subslice_mut_
+  (x : slice u32) (y : usize) (z : usize) : result (slice u32) =
+  core_slice_index_Slice_index_mut u32 (core_ops_range_Range usize)
+    (core_slice_index_SliceIndexRangeUsizeSliceTInst u32) x
+    { start = y; end_ = z }
+
+(** [array::slice_subslice_mut_]: backward function 0
+    Source: 'src/array.rs', lines 68:0-68:75 *)
+let slice_subslice_mut__back
+  (x : slice u32) (y : usize) (z : usize) (ret : slice u32) :
+  result (slice u32)
+  =
+  core_slice_index_Slice_index_mut_back u32 (core_ops_range_Range usize)
+    (core_slice_index_SliceIndexRangeUsizeSliceTInst u32) x
+    { start = y; end_ = z } ret
+
+(** [array::array_to_slice_shared_]: forward function
+    Source: 'src/array.rs', lines 72:0-72:54 *)
+let array_to_slice_shared_ (x : array u32 32) : result (slice u32) =
+  array_to_slice u32 32 x
+
+(** [array::array_to_slice_mut_]: forward function
+    Source: 'src/array.rs', lines 76:0-76:59 *)
+let array_to_slice_mut_ (x : array u32 32) : result (slice u32) =
+  array_to_slice u32 32 x
+
+(** [array::array_to_slice_mut_]: backward function 0
+    Source: 'src/array.rs', lines 76:0-76:59 *)
+let array_to_slice_mut__back
+  (x : array u32 32) (ret : slice u32) : result (array u32 32) =
+  array_from_slice u32 32 x ret
+
+(** [array::array_subslice_shared_]: forward function
+    Source: 'src/array.rs', lines 80:0-80:74 *)
+let array_subslice_shared_
+  (x : array u32 32) (y : usize) (z : usize) : result (slice u32) =
+  core_array_Array_index u32 (core_ops_range_Range usize) 32
+    (core_ops_index_IndexSliceTIInst u32 (core_ops_range_Range usize)
+    (core_slice_index_SliceIndexRangeUsizeSliceTInst u32)) x
+    { start = y; end_ = z }
+
+(** [array::array_subslice_mut_]: forward function
+    Source: 'src/array.rs', lines 84:0-84:79 *)
+let array_subslice_mut_
+  (x : array u32 32) (y : usize) (z : usize) : result (slice u32) =
+  core_array_Array_index_mut u32 (core_ops_range_Range usize) 32
+    (core_ops_index_IndexMutSliceTIInst u32 (core_ops_range_Range usize)
+    (core_slice_index_SliceIndexRangeUsizeSliceTInst u32)) x
+    { start = y; end_ = z }
+
+(** [array::array_subslice_mut_]: backward function 0
+    Source: 'src/array.rs', lines 84:0-84:79 *)
+let array_subslice_mut__back
+  (x : array u32 32) (y : usize) (z : usize) (ret : slice u32) :
+  result (array u32 32)
+  =
+  core_array_Array_index_mut_back u32 (core_ops_range_Range usize) 32
+    (core_ops_index_IndexMutSliceTIInst u32 (core_ops_range_Range usize)
+    (core_slice_index_SliceIndexRangeUsizeSliceTInst u32)) x
+    { start = y; end_ = z } ret
+
+(** [array::index_slice_0]: forward function
+    Source: 'src/array.rs', lines 88:0-88:38 *)
+let index_slice_0 (t : Type0) (s : slice t) : result t =
+  slice_index_usize t s 0
+
+(** [array::index_array_0]: forward function
+    Source: 'src/array.rs', lines 92:0-92:42 *)
+let index_array_0 (t : Type0) (s : array t 32) : result t =
+  array_index_usize t 32 s 0
+
+(** [array::index_index_array]: forward function
+    Source: 'src/array.rs', lines 103:0-103:71 *)
+let index_index_array
+  (s : array (array u32 32) 32) (i : usize) (j : usize) : result u32 =
+  let* a = array_index_usize (array u32 32) 32 s i in
+  array_index_usize u32 32 a j
+
+(** [array::update_update_array]: forward function
+    Source: 'src/array.rs', lines 114:0-114:70 *)
+let update_update_array
+  (s : array (array u32 32) 32) (i : usize) (j : usize) : result unit =
+  let* a = array_index_usize (array u32 32) 32 s i in
+  let* a1 = array_update_usize u32 32 a j 0 in
+  let* _ = array_update_usize (array u32 32) 32 s i a1 in
+  Return ()
+
+(** [array::array_local_deep_copy]: forward function
+    Source: 'src/array.rs', lines 118:0-118:43 *)
+let array_local_deep_copy (x : array u32 32) : result unit =
+  Return ()
+
+(** [array::take_array]: forward function
+    Source: 'src/array.rs', lines 122:0-122:30 *)
+let take_array (a : array u32 2) : result unit =
+  Return ()
+
+(** [array::take_array_borrow]: forward function
+    Source: 'src/array.rs', lines 123:0-123:38 *)
+let take_array_borrow (a : array u32 2) : result unit =
+  Return ()
+
+(** [array::take_slice]: forward function
+    Source: 'src/array.rs', lines 124:0-124:28 *)
+let take_slice (s : slice u32) : result unit =
+  Return ()
+
+(** [array::take_mut_slice]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/array.rs', lines 125:0-125:36 *)
+let take_mut_slice (s : slice u32) : result (slice u32) =
+  Return s
+
+(** [array::const_array]: forward function
+    Source: 'src/array.rs', lines 127:0-127:32 *)
+let const_array : result (array u32 2) =
+  Return (mk_array u32 2 [ 0; 0 ])
+
+(** [array::const_slice]: forward function
+    Source: 'src/array.rs', lines 131:0-131:20 *)
+let const_slice : result unit =
+  let* _ = array_to_slice u32 2 (mk_array u32 2 [ 0; 0 ]) in Return ()
+
+(** [array::take_all]: forward function
+    Source: 'src/array.rs', lines 141:0-141:17 *)
+let take_all : result unit =
+  let* _ = take_array (mk_array u32 2 [ 0; 0 ]) in
+  let* _ = take_array_borrow (mk_array u32 2 [ 0; 0 ]) in
+  let* s = array_to_slice u32 2 (mk_array u32 2 [ 0; 0 ]) in
+  let* _ = take_slice s in
+  let* s1 = array_to_slice u32 2 (mk_array u32 2 [ 0; 0 ]) in
+  let* s2 = take_mut_slice s1 in
+  let* _ = array_from_slice u32 2 (mk_array u32 2 [ 0; 0 ]) s2 in
+  Return ()
+
+(** [array::index_array]: forward function
+    Source: 'src/array.rs', lines 155:0-155:38 *)
+let index_array (x : array u32 2) : result u32 =
+  array_index_usize u32 2 x 0
+
+(** [array::index_array_borrow]: forward function
+    Source: 'src/array.rs', lines 158:0-158:46 *)
+let index_array_borrow (x : array u32 2) : result u32 =
+  array_index_usize u32 2 x 0
+
+(** [array::index_slice_u32_0]: forward function
+    Source: 'src/array.rs', lines 162:0-162:42 *)
+let index_slice_u32_0 (x : slice u32) : result u32 =
+  slice_index_usize u32 x 0
+
+(** [array::index_mut_slice_u32_0]: forward function
+    Source: 'src/array.rs', lines 166:0-166:50 *)
+let index_mut_slice_u32_0 (x : slice u32) : result u32 =
+  slice_index_usize u32 x 0
+
+(** [array::index_mut_slice_u32_0]: backward function 0
+    Source: 'src/array.rs', lines 166:0-166:50 *)
+let index_mut_slice_u32_0_back (x : slice u32) : result (slice u32) =
+  let* _ = slice_index_usize u32 x 0 in Return x
+
+(** [array::index_all]: forward function
+    Source: 'src/array.rs', lines 170:0-170:25 *)
+let index_all : result u32 =
+  let* i = index_array (mk_array u32 2 [ 0; 0 ]) in
+  let* i1 = index_array (mk_array u32 2 [ 0; 0 ]) in
+  let* i2 = u32_add i i1 in
+  let* i3 = index_array_borrow (mk_array u32 2 [ 0; 0 ]) in
+  let* i4 = u32_add i2 i3 in
+  let* s = array_to_slice u32 2 (mk_array u32 2 [ 0; 0 ]) in
+  let* i5 = index_slice_u32_0 s in
+  let* i6 = u32_add i4 i5 in
+  let* s1 = array_to_slice u32 2 (mk_array u32 2 [ 0; 0 ]) in
+  let* i7 = index_mut_slice_u32_0 s1 in
+  let* i8 = u32_add i6 i7 in
+  let* s2 = index_mut_slice_u32_0_back s1 in
+  let* _ = array_from_slice u32 2 (mk_array u32 2 [ 0; 0 ]) s2 in
+  Return i8
+
+(** [array::update_array]: forward function
+    Source: 'src/array.rs', lines 184:0-184:36 *)
+let update_array (x : array u32 2) : result unit =
+  let* _ = array_update_usize u32 2 x 0 1 in Return ()
+
+(** [array::update_array_mut_borrow]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/array.rs', lines 187:0-187:48 *)
+let update_array_mut_borrow (x : array u32 2) : result (array u32 2) =
+  array_update_usize u32 2 x 0 1
+
+(** [array::update_mut_slice]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/array.rs', lines 190:0-190:38 *)
+let update_mut_slice (x : slice u32) : result (slice u32) =
+  slice_update_usize u32 x 0 1
+
+(** [array::update_all]: forward function
+    Source: 'src/array.rs', lines 194:0-194:19 *)
+let update_all : result unit =
+  let* _ = update_array (mk_array u32 2 [ 0; 0 ]) in
+  let* x = update_array_mut_borrow (mk_array u32 2 [ 0; 0 ]) in
+  let* s = array_to_slice u32 2 x in
+  let* s1 = update_mut_slice s in
+  let* _ = array_from_slice u32 2 x s1 in
+  Return ()
+
+(** [array::range_all]: forward function
+    Source: 'src/array.rs', lines 205:0-205:18 *)
+let range_all : result unit =
+  let* s =
+    core_array_Array_index_mut u32 (core_ops_range_Range usize) 4
+      (core_ops_index_IndexMutSliceTIInst u32 (core_ops_range_Range usize)
+      (core_slice_index_SliceIndexRangeUsizeSliceTInst u32))
+      (mk_array u32 4 [ 0; 0; 0; 0 ]) { start = 1; end_ = 3 } in
+  let* s1 = update_mut_slice s in
+  let* _ =
+    core_array_Array_index_mut_back u32 (core_ops_range_Range usize) 4
+      (core_ops_index_IndexMutSliceTIInst u32 (core_ops_range_Range usize)
+      (core_slice_index_SliceIndexRangeUsizeSliceTInst u32))
+      (mk_array u32 4 [ 0; 0; 0; 0 ]) { start = 1; end_ = 3 } s1 in
+  Return ()
+
+(** [array::deref_array_borrow]: forward function
+    Source: 'src/array.rs', lines 214:0-214:46 *)
+let deref_array_borrow (x : array u32 2) : result u32 =
+  array_index_usize u32 2 x 0
+
+(** [array::deref_array_mut_borrow]: forward function
+    Source: 'src/array.rs', lines 219:0-219:54 *)
+let deref_array_mut_borrow (x : array u32 2) : result u32 =
+  array_index_usize u32 2 x 0
+
+(** [array::deref_array_mut_borrow]: backward function 0
+    Source: 'src/array.rs', lines 219:0-219:54 *)
+let deref_array_mut_borrow_back (x : array u32 2) : result (array u32 2) =
+  let* _ = array_index_usize u32 2 x 0 in Return x
+
+(** [array::take_array_t]: forward function
+    Source: 'src/array.rs', lines 227:0-227:31 *)
+let take_array_t (a : array aB_t 2) : result unit =
+  Return ()
+
+(** [array::non_copyable_array]: forward function
+    Source: 'src/array.rs', lines 229:0-229:27 *)
+let non_copyable_array : result unit =
+  let* _ = take_array_t (mk_array aB_t 2 [ AB_A; AB_B ]) in Return ()
+
+(** [array::sum]: loop 0: forward function
+    Source: 'src/array.rs', lines 242:0-250:1 *)
+let rec sum_loop
+  (s : slice u32) (sum1 : u32) (i : usize) :
+  Tot (result u32) (decreases (sum_loop_decreases s sum1 i))
+  =
+  let i1 = slice_len u32 s in
+  if i < i1
+  then
+    let* i2 = slice_index_usize u32 s i in
+    let* sum3 = u32_add sum1 i2 in
+    let* i3 = usize_add i 1 in
+    sum_loop s sum3 i3
+  else Return sum1
+
+(** [array::sum]: forward function
+    Source: 'src/array.rs', lines 242:0-242:28 *)
+let sum (s : slice u32) : result u32 =
+  sum_loop s 0 0
+
+(** [array::sum2]: loop 0: forward function
+    Source: 'src/array.rs', lines 252:0-261:1 *)
+let rec sum2_loop
+  (s : slice u32) (s2 : slice u32) (sum1 : u32) (i : usize) :
+  Tot (result u32) (decreases (sum2_loop_decreases s s2 sum1 i))
+  =
+  let i1 = slice_len u32 s in
+  if i < i1
+  then
+    let* i2 = slice_index_usize u32 s i in
+    let* i3 = slice_index_usize u32 s2 i in
+    let* i4 = u32_add i2 i3 in
+    let* sum3 = u32_add sum1 i4 in
+    let* i5 = usize_add i 1 in
+    sum2_loop s s2 sum3 i5
+  else Return sum1
+
+(** [array::sum2]: forward function
+    Source: 'src/array.rs', lines 252:0-252:41 *)
+let sum2 (s : slice u32) (s2 : slice u32) : result u32 =
+  let i = slice_len u32 s in
+  let i1 = slice_len u32 s2 in
+  if not (i = i1) then Fail Failure else sum2_loop s s2 0 0
+
+(** [array::f0]: forward function
+    Source: 'src/array.rs', lines 263:0-263:11 *)
+let f0 : result unit =
+  let* s = array_to_slice u32 2 (mk_array u32 2 [ 1; 2 ]) in
+  let* s1 = slice_update_usize u32 s 0 1 in
+  let* _ = array_from_slice u32 2 (mk_array u32 2 [ 1; 2 ]) s1 in
+  Return ()
+
+(** [array::f1]: forward function
+    Source: 'src/array.rs', lines 268:0-268:11 *)
+let f1 : result unit =
+  let* _ = array_update_usize u32 2 (mk_array u32 2 [ 1; 2 ]) 0 1 in Return ()
+
+(** [array::f2]: forward function
+    Source: 'src/array.rs', lines 273:0-273:17 *)
+let f2 (i : u32) : result unit =
+  Return ()
+
+(** [array::f4]: forward function
+    Source: 'src/array.rs', lines 282:0-282:54 *)
+let f4 (x : array u32 32) (y : usize) (z : usize) : result (slice u32) =
+  core_array_Array_index u32 (core_ops_range_Range usize) 32
+    (core_ops_index_IndexSliceTIInst u32 (core_ops_range_Range usize)
+    (core_slice_index_SliceIndexRangeUsizeSliceTInst u32)) x
+    { start = y; end_ = z }
+
+(** [array::f3]: forward function
+    Source: 'src/array.rs', lines 275:0-275:18 *)
+let f3 : result u32 =
+  let* i = array_index_usize u32 2 (mk_array u32 2 [ 1; 2 ]) 0 in
+  let* _ = f2 i in
+  let b = array_repeat u32 32 0 in
+  let* s = array_to_slice u32 2 (mk_array u32 2 [ 1; 2 ]) in
+  let* s1 = f4 b 16 18 in
+  sum2 s s1
+
+(** [array::SZ]
+    Source: 'src/array.rs', lines 286:0-286:19 *)
+let sz_body : result usize = Return 32
+let sz_c : usize = eval_global sz_body
+
+(** [array::f5]: forward function
+    Source: 'src/array.rs', lines 289:0-289:31 *)
+let f5 (x : array u32 32) : result u32 =
+  array_index_usize u32 32 x 0
+
+(** [array::ite]: forward function
+    Source: 'src/array.rs', lines 294:0-294:12 *)
+let ite : result unit =
+  let* s = array_to_slice u32 2 (mk_array u32 2 [ 0; 0 ]) in
+  let* s1 = array_to_slice u32 2 (mk_array u32 2 [ 0; 0 ]) in
+  let* s2 = index_mut_slice_u32_0_back s1 in
+  let* _ = array_from_slice u32 2 (mk_array u32 2 [ 0; 0 ]) s2 in
+  let* s3 = index_mut_slice_u32_0_back s in
+  let* _ = array_from_slice u32 2 (mk_array u32 2 [ 0; 0 ]) s3 in
+  Return ()
+
diff --git a/tests/fstar-split/array/Array.Types.fst b/tests/fstar-split/array/Array.Types.fst
new file mode 100644
index 00000000..312f6018
--- /dev/null
+++ b/tests/fstar-split/array/Array.Types.fst
@@ -0,0 +1,11 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [array]: type definitions *)
+module Array.Types
+open Primitives
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [array::AB]
+    Source: 'src/array.rs', lines 3:0-3:11 *)
+type aB_t = | AB_A : aB_t | AB_B : aB_t
+
diff --git a/tests/fstar-split/array/Makefile b/tests/fstar-split/array/Makefile
new file mode 100644
index 00000000..fa7d1f36
--- /dev/null
+++ b/tests/fstar-split/array/Makefile
@@ -0,0 +1,49 @@
+# This file was automatically generated - modify ../Makefile.template instead
+INCLUDE_DIRS = .
+
+FSTAR_INCLUDES = $(addprefix --include ,$(INCLUDE_DIRS))
+
+FSTAR_HINTS ?= --use_hints --use_hint_hashes --record_hints
+
+FSTAR_OPTIONS = $(FSTAR_HINTS) \
+  --cache_checked_modules $(FSTAR_INCLUDES) --cmi \
+  --warn_error '+241@247+285-274' \
+
+FSTAR_EXE ?= fstar.exe
+FSTAR_NO_FLAGS = $(FSTAR_EXE) --already_cached 'Prims FStar LowStar Steel' --odir obj --cache_dir obj
+
+FSTAR = $(FSTAR_NO_FLAGS) $(FSTAR_OPTIONS)
+
+# The F* roots are used to compute the dependency graph, and generate the .depend file
+FSTAR_ROOTS ?= $(wildcard *.fst *.fsti)
+
+# Build all the files
+all: $(addprefix obj/,$(addsuffix .checked,$(FSTAR_ROOTS)))
+
+# This is the right way to ensure the .depend file always gets re-built.
+ifeq (,$(filter %-in,$(MAKECMDGOALS)))
+ifndef NODEPEND
+ifndef MAKE_RESTARTS
+.depend: .FORCE
+	$(FSTAR_NO_FLAGS) --dep full $(notdir $(FSTAR_ROOTS)) > $@
+
+.PHONY: .FORCE
+.FORCE:
+endif
+endif
+
+include .depend
+endif
+
+# For the interactive mode
+%.fst-in %.fsti-in:
+	@echo $(FSTAR_OPTIONS)
+
+# Generete the .checked files in batch mode
+%.checked:
+	$(FSTAR) $(FSTAR_OPTIONS) $< && \
+	touch -c $@
+
+.PHONY: clean
+clean:
+	rm -f obj/*
diff --git a/tests/fstar-split/array/Primitives.fst b/tests/fstar-split/array/Primitives.fst
new file mode 100644
index 00000000..a3ffbde4
--- /dev/null
+++ b/tests/fstar-split/array/Primitives.fst
@@ -0,0 +1,884 @@
+/// This file lists primitive and assumed functions and types
+module Primitives
+open FStar.Mul
+open FStar.List.Tot
+
+#set-options "--z3rlimit 15 --fuel 0 --ifuel 1"
+
+(*** Utilities *)
+val list_update (#a : Type0) (ls : list a) (i : nat{i < length ls}) (x : a) :
+  ls':list a{
+    length ls' = length ls /\
+    index ls' i == x
+  }
+#push-options "--fuel 1"
+let rec list_update #a ls i x =
+  match ls with
+  | x' :: ls -> if i = 0 then x :: ls else x' :: list_update ls (i-1) x
+#pop-options
+
+(*** Result *)
+type error : Type0 =
+| Failure
+| OutOfFuel
+
+type result (a : Type0) : Type0 =
+| Return : v:a -> result a
+| Fail : e:error -> result a
+
+// Monadic return operator
+unfold let return (#a : Type0) (x : a) : result a = Return x
+
+// Monadic bind operator.
+// Allows to use the notation:
+// ```
+// let* x = y in
+// ...
+// ```
+unfold let (let*) (#a #b : Type0) (m: result a)
+  (f: (x:a) -> Pure (result b) (requires (m == Return x)) (ensures fun _ -> True)) :
+  result b =
+  match m with
+  | Return x -> f x
+  | Fail e   -> Fail e
+
+// Monadic assert(...)
+let massert (b:bool) : result unit = if b then Return () else Fail Failure
+
+// Normalize and unwrap a successful result (used for globals).
+let eval_global (#a : Type0) (x : result a{Return? (normalize_term x)}) : a = Return?.v x
+
+(*** Misc *)
+type char = FStar.Char.char
+type string = string
+
+let is_zero (n: nat) : bool = n = 0
+let decrease (n: nat{n > 0}) : nat = n - 1
+
+let core_mem_replace (a : Type0) (x : a) (y : a) : a = x
+let core_mem_replace_back (a : Type0) (x : a) (y : a) : a = y
+
+// We don't really use raw pointers for now
+type mut_raw_ptr (t : Type0) = { v : t }
+type const_raw_ptr (t : Type0) = { v : t }
+
+(*** Scalars *)
+/// Rem.: most of the following code was partially generated
+
+assume val size_numbits : pos
+
+// TODO: we could use FStar.Int.int_t and FStar.UInt.int_t
+
+let isize_min : int = -9223372036854775808 // TODO: should be opaque
+let isize_max : int = 9223372036854775807 // TODO: should be opaque
+let i8_min : int = -128
+let i8_max : int = 127
+let i16_min : int = -32768
+let i16_max : int = 32767
+let i32_min : int = -2147483648
+let i32_max : int = 2147483647
+let i64_min : int = -9223372036854775808
+let i64_max : int = 9223372036854775807
+let i128_min : int = -170141183460469231731687303715884105728
+let i128_max : int = 170141183460469231731687303715884105727
+let usize_min : int = 0
+let usize_max : int = 4294967295 // TODO: should be opaque
+let u8_min : int = 0
+let u8_max : int = 255
+let u16_min : int = 0
+let u16_max : int = 65535
+let u32_min : int = 0
+let u32_max : int = 4294967295
+let u64_min : int = 0
+let u64_max : int = 18446744073709551615
+let u128_min : int = 0
+let u128_max : int = 340282366920938463463374607431768211455
+
+type scalar_ty =
+| Isize
+| I8
+| I16
+| I32
+| I64
+| I128
+| Usize
+| U8
+| U16
+| U32
+| U64
+| U128
+
+let is_unsigned = function
+  | Isize | I8 | I16 | I32 | I64 | I128 -> false
+  | Usize | U8 | U16 | U32 | U64 | U128 -> true
+
+let scalar_min (ty : scalar_ty) : int =
+  match ty with
+  | Isize -> isize_min
+  | I8 -> i8_min
+  | I16 -> i16_min
+  | I32 -> i32_min
+  | I64 -> i64_min
+  | I128 -> i128_min
+  | Usize -> usize_min
+  | U8 -> u8_min
+  | U16 -> u16_min
+  | U32 -> u32_min
+  | U64 -> u64_min
+  | U128 -> u128_min
+
+let scalar_max (ty : scalar_ty) : int =
+  match ty with
+  | Isize -> isize_max
+  | I8 -> i8_max
+  | I16 -> i16_max
+  | I32 -> i32_max
+  | I64 -> i64_max
+  | I128 -> i128_max
+  | Usize -> usize_max
+  | U8 -> u8_max
+  | U16 -> u16_max
+  | U32 -> u32_max
+  | U64 -> u64_max
+  | U128 -> u128_max
+
+type scalar (ty : scalar_ty) : eqtype = x:int{scalar_min ty <= x && x <= scalar_max ty}
+
+let mk_scalar (ty : scalar_ty) (x : int) : result (scalar ty) =
+  if scalar_min ty <= x && scalar_max ty >= x then Return x else Fail Failure
+
+let scalar_neg (#ty : scalar_ty) (x : scalar ty) : result (scalar ty) = mk_scalar ty (-x)
+
+let scalar_div (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  if y <> 0 then mk_scalar ty (x / y) else Fail Failure
+
+/// The remainder operation
+let int_rem (x : int) (y : int{y <> 0}) : int =
+  if x >= 0 then (x % y) else -(x % y)
+
+(* Checking consistency with Rust *)
+let _ = assert_norm(int_rem 1 2 = 1)
+let _ = assert_norm(int_rem (-1) 2 = -1)
+let _ = assert_norm(int_rem 1 (-2) = 1)
+let _ = assert_norm(int_rem (-1) (-2) = -1)
+
+let scalar_rem (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  if y <> 0 then mk_scalar ty (int_rem x y) else Fail Failure
+
+let scalar_add (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  mk_scalar ty (x + y)
+
+let scalar_sub (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  mk_scalar ty (x - y)
+
+let scalar_mul (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  mk_scalar ty (x * y)
+
+let scalar_xor (#ty : scalar_ty)
+    (x : scalar ty) (y : scalar ty) : scalar ty =
+  match ty with
+  | U8 -> FStar.UInt.logxor #8 x y
+  | U16 -> FStar.UInt.logxor #16 x y
+  | U32 -> FStar.UInt.logxor #32 x y
+  | U64 -> FStar.UInt.logxor #64 x y
+  | U128 -> FStar.UInt.logxor #128 x y
+  | Usize -> admit() // TODO
+  | I8 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 8);
+    normalize_spec (scalar I8);
+    FStar.Int.logxor #8 x y
+  | I16 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 16);
+    normalize_spec (scalar I16);
+    FStar.Int.logxor #16 x y
+  | I32 -> FStar.Int.logxor #32 x y
+  | I64 -> FStar.Int.logxor #64 x y
+  | I128 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 128);
+    normalize_spec (scalar I128);
+    FStar.Int.logxor #128 x y
+  | Isize -> admit() // TODO
+
+let scalar_or (#ty : scalar_ty)
+    (x : scalar ty) (y : scalar ty) : scalar ty =
+  match ty with
+  | U8 -> FStar.UInt.logor #8 x y
+  | U16 -> FStar.UInt.logor #16 x y
+  | U32 -> FStar.UInt.logor #32 x y
+  | U64 -> FStar.UInt.logor #64 x y
+  | U128 -> FStar.UInt.logor #128 x y
+  | Usize -> admit() // TODO
+  | I8 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 8);
+    normalize_spec (scalar I8);
+    FStar.Int.logor #8 x y
+  | I16 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 16);
+    normalize_spec (scalar I16);
+    FStar.Int.logor #16 x y
+  | I32 -> FStar.Int.logor #32 x y
+  | I64 -> FStar.Int.logor #64 x y
+  | I128 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 128);
+    normalize_spec (scalar I128);
+    FStar.Int.logor #128 x y
+  | Isize -> admit() // TODO
+
+let scalar_and (#ty : scalar_ty)
+    (x : scalar ty) (y : scalar ty) : scalar ty =
+  match ty with
+  | U8 -> FStar.UInt.logand #8 x y
+  | U16 -> FStar.UInt.logand #16 x y
+  | U32 -> FStar.UInt.logand #32 x y
+  | U64 -> FStar.UInt.logand #64 x y
+  | U128 -> FStar.UInt.logand #128 x y
+  | Usize -> admit() // TODO
+  | I8 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 8);
+    normalize_spec (scalar I8);
+    FStar.Int.logand #8 x y
+  | I16 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 16);
+    normalize_spec (scalar I16);
+    FStar.Int.logand #16 x y
+  | I32 -> FStar.Int.logand #32 x y
+  | I64 -> FStar.Int.logand #64 x y
+  | I128 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 128);
+    normalize_spec (scalar I128);
+    FStar.Int.logand #128 x y
+  | Isize -> admit() // TODO
+
+// Shift left
+let scalar_shl (#ty0 #ty1 : scalar_ty)
+    (x : scalar ty0) (y : scalar ty1) : result (scalar ty0) =
+  admit()
+
+// Shift right
+let scalar_shr (#ty0 #ty1 : scalar_ty)
+    (x : scalar ty0) (y : scalar ty1) : result (scalar ty0) =
+  admit()
+
+(** Cast an integer from a [src_ty] to a [tgt_ty] *)
+// TODO: check the semantics of casts in Rust
+let scalar_cast (src_ty : scalar_ty) (tgt_ty : scalar_ty) (x : scalar src_ty) : result (scalar tgt_ty) =
+  mk_scalar tgt_ty x
+
+// This can't fail, but for now we make all casts faillible (easier for the translation)
+let scalar_cast_bool (tgt_ty : scalar_ty) (x : bool) : result (scalar tgt_ty) =
+  mk_scalar tgt_ty (if x then 1 else 0)
+
+/// The scalar types
+type isize : eqtype = scalar Isize
+type i8    : eqtype = scalar I8
+type i16   : eqtype = scalar I16
+type i32   : eqtype = scalar I32
+type i64   : eqtype = scalar I64
+type i128  : eqtype = scalar I128
+type usize : eqtype = scalar Usize
+type u8    : eqtype = scalar U8
+type u16   : eqtype = scalar U16
+type u32   : eqtype = scalar U32
+type u64   : eqtype = scalar U64
+type u128  : eqtype = scalar U128
+
+
+let core_isize_min : isize = isize_min
+let core_isize_max : isize = isize_max
+let core_i8_min    : i8 = i8_min
+let core_i8_max    : i8 = i8_max
+let core_i16_min   : i16 = i16_min
+let core_i16_max   : i16 = i16_max
+let core_i32_min   : i32 = i32_min
+let core_i32_max   : i32 = i32_max
+let core_i64_min   : i64 = i64_min
+let core_i64_max   : i64 = i64_max
+let core_i128_min  : i128 = i128_min
+let core_i128_max  : i128 = i128_max
+
+let core_usize_min : usize = usize_min
+let core_usize_max : usize = usize_max
+let core_u8_min    : u8 = u8_min
+let core_u8_max    : u8 = u8_max
+let core_u16_min   : u16 = u16_min
+let core_u16_max   : u16 = u16_max
+let core_u32_min   : u32 = u32_min
+let core_u32_max   : u32 = u32_max
+let core_u64_min   : u64 = u64_min
+let core_u64_max   : u64 = u64_max
+let core_u128_min  : u128 = u128_min
+let core_u128_max  : u128 = u128_max
+
+/// Negation
+let isize_neg = scalar_neg #Isize
+let i8_neg = scalar_neg #I8
+let i16_neg = scalar_neg #I16
+let i32_neg = scalar_neg #I32
+let i64_neg = scalar_neg #I64
+let i128_neg = scalar_neg #I128
+
+/// Division
+let isize_div = scalar_div #Isize
+let i8_div = scalar_div #I8
+let i16_div = scalar_div #I16
+let i32_div = scalar_div #I32
+let i64_div = scalar_div #I64
+let i128_div = scalar_div #I128
+let usize_div = scalar_div #Usize
+let u8_div = scalar_div #U8
+let u16_div = scalar_div #U16
+let u32_div = scalar_div #U32
+let u64_div = scalar_div #U64
+let u128_div = scalar_div #U128
+
+/// Remainder
+let isize_rem = scalar_rem #Isize
+let i8_rem = scalar_rem #I8
+let i16_rem = scalar_rem #I16
+let i32_rem = scalar_rem #I32
+let i64_rem = scalar_rem #I64
+let i128_rem = scalar_rem #I128
+let usize_rem = scalar_rem #Usize
+let u8_rem = scalar_rem #U8
+let u16_rem = scalar_rem #U16
+let u32_rem = scalar_rem #U32
+let u64_rem = scalar_rem #U64
+let u128_rem = scalar_rem #U128
+
+/// Addition
+let isize_add = scalar_add #Isize
+let i8_add = scalar_add #I8
+let i16_add = scalar_add #I16
+let i32_add = scalar_add #I32
+let i64_add = scalar_add #I64
+let i128_add = scalar_add #I128
+let usize_add = scalar_add #Usize
+let u8_add = scalar_add #U8
+let u16_add = scalar_add #U16
+let u32_add = scalar_add #U32
+let u64_add = scalar_add #U64
+let u128_add = scalar_add #U128
+
+/// Subtraction
+let isize_sub = scalar_sub #Isize
+let i8_sub = scalar_sub #I8
+let i16_sub = scalar_sub #I16
+let i32_sub = scalar_sub #I32
+let i64_sub = scalar_sub #I64
+let i128_sub = scalar_sub #I128
+let usize_sub = scalar_sub #Usize
+let u8_sub = scalar_sub #U8
+let u16_sub = scalar_sub #U16
+let u32_sub = scalar_sub #U32
+let u64_sub = scalar_sub #U64
+let u128_sub = scalar_sub #U128
+
+/// Multiplication
+let isize_mul = scalar_mul #Isize
+let i8_mul = scalar_mul #I8
+let i16_mul = scalar_mul #I16
+let i32_mul = scalar_mul #I32
+let i64_mul = scalar_mul #I64
+let i128_mul = scalar_mul #I128
+let usize_mul = scalar_mul #Usize
+let u8_mul = scalar_mul #U8
+let u16_mul = scalar_mul #U16
+let u32_mul = scalar_mul #U32
+let u64_mul = scalar_mul #U64
+let u128_mul = scalar_mul #U128
+
+/// Xor
+let u8_xor = scalar_xor #U8
+let u16_xor = scalar_xor #U16
+let u32_xor = scalar_xor #U32
+let u64_xor = scalar_xor #U64
+let u128_xor = scalar_xor #U128
+let usize_xor = scalar_xor #Usize
+let i8_xor = scalar_xor #I8
+let i16_xor = scalar_xor #I16
+let i32_xor = scalar_xor #I32
+let i64_xor = scalar_xor #I64
+let i128_xor = scalar_xor #I128
+let isize_xor = scalar_xor #Isize
+
+/// Or
+let u8_or = scalar_or #U8
+let u16_or = scalar_or #U16
+let u32_or = scalar_or #U32
+let u64_or = scalar_or #U64
+let u128_or = scalar_or #U128
+let usize_or = scalar_or #Usize
+let i8_or = scalar_or #I8
+let i16_or = scalar_or #I16
+let i32_or = scalar_or #I32
+let i64_or = scalar_or #I64
+let i128_or = scalar_or #I128
+let isize_or = scalar_or #Isize
+
+/// And
+let u8_and = scalar_and #U8
+let u16_and = scalar_and #U16
+let u32_and = scalar_and #U32
+let u64_and = scalar_and #U64
+let u128_and = scalar_and #U128
+let usize_and = scalar_and #Usize
+let i8_and = scalar_and #I8
+let i16_and = scalar_and #I16
+let i32_and = scalar_and #I32
+let i64_and = scalar_and #I64
+let i128_and = scalar_and #I128
+let isize_and = scalar_and #Isize
+
+/// Shift left
+let u8_shl #ty = scalar_shl #U8 #ty
+let u16_shl #ty = scalar_shl #U16 #ty
+let u32_shl #ty = scalar_shl #U32 #ty
+let u64_shl #ty = scalar_shl #U64 #ty
+let u128_shl #ty = scalar_shl #U128 #ty
+let usize_shl #ty = scalar_shl #Usize #ty
+let i8_shl #ty = scalar_shl #I8 #ty
+let i16_shl #ty = scalar_shl #I16 #ty
+let i32_shl #ty = scalar_shl #I32 #ty
+let i64_shl #ty = scalar_shl #I64 #ty
+let i128_shl #ty = scalar_shl #I128 #ty
+let isize_shl #ty = scalar_shl #Isize #ty
+
+/// Shift right
+let u8_shr #ty = scalar_shr #U8 #ty
+let u16_shr #ty = scalar_shr #U16 #ty
+let u32_shr #ty = scalar_shr #U32 #ty
+let u64_shr #ty = scalar_shr #U64 #ty
+let u128_shr #ty = scalar_shr #U128 #ty
+let usize_shr #ty = scalar_shr #Usize #ty
+let i8_shr #ty = scalar_shr #I8 #ty
+let i16_shr #ty = scalar_shr #I16 #ty
+let i32_shr #ty = scalar_shr #I32 #ty
+let i64_shr #ty = scalar_shr #I64 #ty
+let i128_shr #ty = scalar_shr #I128 #ty
+let isize_shr #ty = scalar_shr #Isize #ty
+
+(*** core::ops *)
+
+// Trait declaration: [core::ops::index::Index]
+noeq type core_ops_index_Index (self idx : Type0) = {
+  output : Type0;
+  index : self → idx → result output
+}
+
+// Trait declaration: [core::ops::index::IndexMut]
+noeq type core_ops_index_IndexMut (self idx : Type0) = {
+  indexInst : core_ops_index_Index self idx;
+  index_mut : self → idx → result indexInst.output;
+  index_mut_back : self → idx → indexInst.output → result self;
+}
+
+// Trait declaration [core::ops::deref::Deref]
+noeq type core_ops_deref_Deref (self : Type0) = {
+  target : Type0;
+  deref : self → result target;
+}
+
+// Trait declaration [core::ops::deref::DerefMut]
+noeq type core_ops_deref_DerefMut (self : Type0) = {
+  derefInst : core_ops_deref_Deref self;
+  deref_mut : self → result derefInst.target;
+  deref_mut_back : self → derefInst.target → result self;
+}
+
+type core_ops_range_Range (a : Type0) = {
+  start : a;
+  end_ : a;
+}
+
+(*** [alloc] *)
+
+let alloc_boxed_Box_deref (t : Type0) (x : t) : result t = Return x
+let alloc_boxed_Box_deref_mut (t : Type0) (x : t) : result t = Return x
+let alloc_boxed_Box_deref_mut_back (t : Type) (_ : t) (x : t) : result t = Return x
+
+// Trait instance
+let alloc_boxed_Box_coreopsDerefInst (self : Type0) : core_ops_deref_Deref self = {
+  target = self;
+  deref = alloc_boxed_Box_deref self;
+}
+
+// Trait instance
+let alloc_boxed_Box_coreopsDerefMutInst (self : Type0) : core_ops_deref_DerefMut self = {
+  derefInst = alloc_boxed_Box_coreopsDerefInst self;
+  deref_mut = alloc_boxed_Box_deref_mut self;
+  deref_mut_back = alloc_boxed_Box_deref_mut_back self;
+}
+
+(*** Array *)
+type array (a : Type0) (n : usize) = s:list a{length s = n}
+
+// We tried putting the normalize_term condition as a refinement on the list
+// but it didn't work. It works with the requires clause.
+let mk_array (a : Type0) (n : usize)
+  (l : list a) :
+  Pure (array a n)
+  (requires (normalize_term(FStar.List.Tot.length l) = n))
+  (ensures (fun _ -> True)) =
+  normalize_term_spec (FStar.List.Tot.length l);
+  l
+
+let array_index_usize (a : Type0) (n : usize) (x : array a n) (i : usize) : result a =
+  if i < length x then Return (index x i)
+  else Fail Failure
+
+let array_update_usize (a : Type0) (n : usize) (x : array a n) (i : usize) (nx : a) : result (array a n) =
+  if i < length x then Return (list_update x i nx)
+  else Fail Failure
+
+(*** Slice *)
+type slice (a : Type0) = s:list a{length s <= usize_max}
+
+let slice_len (a : Type0) (s : slice a) : usize = length s
+
+let slice_index_usize (a : Type0) (x : slice a) (i : usize) : result a =
+  if i < length x then Return (index x i)
+  else Fail Failure
+
+let slice_update_usize (a : Type0) (x : slice a) (i : usize) (nx : a) : result (slice a) =
+  if i < length x then Return (list_update x i nx)
+  else Fail Failure
+
+(*** Subslices *)
+
+let array_to_slice (a : Type0) (n : usize) (x : array a n) : result (slice a) = Return x
+let array_from_slice (a : Type0) (n : usize) (x : array a n) (s : slice a) : result (array a n) =
+  if length s = n then Return s
+  else Fail Failure
+
+// TODO: finish the definitions below (there lacks [List.drop] and [List.take] in the standard library *)
+let array_subslice (a : Type0) (n : usize) (x : array a n) (r : core_ops_range_Range usize) : result (slice a) =
+  admit()
+
+let array_update_subslice (a : Type0) (n : usize) (x : array a n) (r : core_ops_range_Range usize) (ns : slice a) : result (array a n) =
+  admit()
+
+let array_repeat (a : Type0) (n : usize) (x : a) : array a n =
+  admit()
+
+let slice_subslice (a : Type0) (x : slice a) (r : core_ops_range_Range usize) : result (slice a) =
+  admit()
+
+let slice_update_subslice (a : Type0) (x : slice a) (r : core_ops_range_Range usize) (ns : slice a) : result (slice a) =
+  admit()
+
+(*** Vector *)
+type alloc_vec_Vec (a : Type0) = v:list a{length v <= usize_max}
+
+let alloc_vec_Vec_new (a  : Type0) : alloc_vec_Vec a = assert_norm(length #a [] == 0); []
+let alloc_vec_Vec_len (a : Type0) (v : alloc_vec_Vec a) : usize = length v
+
+// Helper
+let alloc_vec_Vec_index_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) : result a =
+  if i < length v then Return (index v i) else Fail Failure
+// Helper
+let alloc_vec_Vec_update_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
+  if i < length v then Return (list_update v i x) else Fail Failure
+
+// The **forward** function shouldn't be used
+let alloc_vec_Vec_push_fwd (a  : Type0) (v : alloc_vec_Vec a) (x : a) : unit = ()
+let alloc_vec_Vec_push (a  : Type0) (v : alloc_vec_Vec a) (x : a) :
+  Pure (result (alloc_vec_Vec a))
+  (requires True)
+  (ensures (fun res ->
+    match res with
+    | Fail e -> e == Failure
+    | Return v' -> length v' = length v + 1)) =
+  if length v < usize_max then begin
+    (**) assert_norm(length [x] == 1);
+    (**) append_length v [x];
+    (**) assert(length (append v [x]) = length v + 1);
+    Return (append v [x])
+    end
+  else Fail Failure
+
+// The **forward** function shouldn't be used
+let alloc_vec_Vec_insert_fwd (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result unit =
+  if i < length v then Return () else Fail Failure
+let alloc_vec_Vec_insert (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
+  if i < length v then Return (list_update v i x) else Fail Failure
+
+// Trait declaration: [core::slice::index::private_slice_index::Sealed]
+type core_slice_index_private_slice_index_Sealed (self : Type0) = unit
+
+// Trait declaration: [core::slice::index::SliceIndex]
+noeq type core_slice_index_SliceIndex (self t : Type0) = {
+  sealedInst : core_slice_index_private_slice_index_Sealed self;
+  output : Type0;
+  get : self → t → result (option output);
+  get_mut : self → t → result (option output);
+  get_mut_back : self → t → option output → result t;
+  get_unchecked : self → const_raw_ptr t → result (const_raw_ptr output);
+  get_unchecked_mut : self → mut_raw_ptr t → result (mut_raw_ptr output);
+  index : self → t → result output;
+  index_mut : self → t → result output;
+  index_mut_back : self → t → output → result t;
+}
+
+// [core::slice::index::[T]::index]: forward function
+let core_slice_index_Slice_index
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (s : slice t) (i : idx) : result inst.output =
+  let* x = inst.get i s in
+  match x with
+  | None -> Fail Failure
+  | Some x -> Return x
+
+// [core::slice::index::Range:::get]: forward function
+let core_slice_index_RangeUsize_get (t : Type0) (i : core_ops_range_Range usize) (s : slice t) :
+  result (option (slice t)) =
+  admit () // TODO
+
+// [core::slice::index::Range::get_mut]: forward function
+let core_slice_index_RangeUsize_get_mut
+  (t : Type0) : core_ops_range_Range usize → slice t → result (option (slice t)) =
+  admit () // TODO
+
+// [core::slice::index::Range::get_mut]: backward function 0
+let core_slice_index_RangeUsize_get_mut_back
+  (t : Type0) :
+  core_ops_range_Range usize → slice t → option (slice t) → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::Range::get_unchecked]: forward function
+let core_slice_index_RangeUsize_get_unchecked
+  (t : Type0) :
+  core_ops_range_Range usize → const_raw_ptr (slice t) → result (const_raw_ptr (slice t)) =
+  // Don't know what the model should be - for now we always fail to make
+  // sure code which uses it fails
+  fun _ _ -> Fail Failure
+
+// [core::slice::index::Range::get_unchecked_mut]: forward function
+let core_slice_index_RangeUsize_get_unchecked_mut
+  (t : Type0) :
+  core_ops_range_Range usize → mut_raw_ptr (slice t) → result (mut_raw_ptr (slice t)) =
+  // Don't know what the model should be - for now we always fail to make
+  // sure code which uses it fails
+  fun _ _ -> Fail Failure
+
+// [core::slice::index::Range::index]: forward function
+let core_slice_index_RangeUsize_index
+  (t : Type0) : core_ops_range_Range usize → slice t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::Range::index_mut]: forward function
+let core_slice_index_RangeUsize_index_mut
+  (t : Type0) : core_ops_range_Range usize → slice t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::Range::index_mut]: backward function 0
+let core_slice_index_RangeUsize_index_mut_back
+  (t : Type0) : core_ops_range_Range usize → slice t → slice t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::[T]::index_mut]: forward function
+let core_slice_index_Slice_index_mut
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
+  slice t → idx → result inst.output =
+  admit () // 
+
+// [core::slice::index::[T]::index_mut]: backward function 0
+let core_slice_index_Slice_index_mut_back
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
+  slice t → idx → inst.output → result (slice t) =
+  admit () // TODO
+
+// [core::array::[T; N]::index]: forward function
+let core_array_Array_index
+  (t idx : Type0) (n : usize) (inst : core_ops_index_Index (slice t) idx)
+  (a : array t n) (i : idx) : result inst.output =
+  admit () // TODO
+
+// [core::array::[T; N]::index_mut]: forward function
+let core_array_Array_index_mut
+  (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
+  (a : array t n) (i : idx) : result inst.indexInst.output =
+  admit () // TODO
+
+// [core::array::[T; N]::index_mut]: backward function 0
+let core_array_Array_index_mut_back
+  (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
+  (a : array t n) (i : idx) (x : inst.indexInst.output) : result (array t n) =
+  admit () // TODO
+
+// Trait implementation: [core::slice::index::private_slice_index::Range]
+let core_slice_index_private_slice_index_SealedRangeUsizeInst
+  : core_slice_index_private_slice_index_Sealed (core_ops_range_Range usize) = ()
+
+// Trait implementation: [core::slice::index::Range]
+let core_slice_index_SliceIndexRangeUsizeSliceTInst (t : Type0) :
+  core_slice_index_SliceIndex (core_ops_range_Range usize) (slice t) = {
+  sealedInst = core_slice_index_private_slice_index_SealedRangeUsizeInst;
+  output = slice t;
+  get = core_slice_index_RangeUsize_get t;
+  get_mut = core_slice_index_RangeUsize_get_mut t;
+  get_mut_back = core_slice_index_RangeUsize_get_mut_back t;
+  get_unchecked = core_slice_index_RangeUsize_get_unchecked t;
+  get_unchecked_mut = core_slice_index_RangeUsize_get_unchecked_mut t;
+  index = core_slice_index_RangeUsize_index t;
+  index_mut = core_slice_index_RangeUsize_index_mut t;
+  index_mut_back = core_slice_index_RangeUsize_index_mut_back t;
+}
+
+// Trait implementation: [core::slice::index::[T]]
+let core_ops_index_IndexSliceTIInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_Index (slice t) idx = {
+  output = inst.output;
+  index = core_slice_index_Slice_index t idx inst;
+}
+
+// Trait implementation: [core::slice::index::[T]]
+let core_ops_index_IndexMutSliceTIInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_IndexMut (slice t) idx = {
+  indexInst = core_ops_index_IndexSliceTIInst t idx inst;
+  index_mut = core_slice_index_Slice_index_mut t idx inst;
+  index_mut_back = core_slice_index_Slice_index_mut_back t idx inst;
+}
+
+// Trait implementation: [core::array::[T; N]]
+let core_ops_index_IndexArrayInst (t idx : Type0) (n : usize)
+  (inst : core_ops_index_Index (slice t) idx) :
+  core_ops_index_Index (array t n) idx = {
+  output = inst.output;
+  index = core_array_Array_index t idx n inst;
+}
+
+// Trait implementation: [core::array::[T; N]]
+let core_ops_index_IndexMutArrayIInst (t idx : Type0) (n : usize)
+  (inst : core_ops_index_IndexMut (slice t) idx) :
+  core_ops_index_IndexMut (array t n) idx = {
+  indexInst = core_ops_index_IndexArrayInst t idx n inst.indexInst;
+  index_mut = core_array_Array_index_mut t idx n inst;
+  index_mut_back = core_array_Array_index_mut_back t idx n inst;
+}
+
+// [core::slice::index::usize::get]: forward function
+let core_slice_index_usize_get
+  (t : Type0) : usize → slice t → result (option t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_mut]: forward function
+let core_slice_index_usize_get_mut
+  (t : Type0) : usize → slice t → result (option t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_mut]: backward function 0
+let core_slice_index_usize_get_mut_back
+  (t : Type0) : usize → slice t → option t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_unchecked]: forward function
+let core_slice_index_usize_get_unchecked
+  (t : Type0) : usize → const_raw_ptr (slice t) → result (const_raw_ptr t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_unchecked_mut]: forward function
+let core_slice_index_usize_get_unchecked_mut
+  (t : Type0) : usize → mut_raw_ptr (slice t) → result (mut_raw_ptr t) =
+  admit () // TODO
+
+// [core::slice::index::usize::index]: forward function
+let core_slice_index_usize_index (t : Type0) : usize → slice t → result t =
+  admit () // TODO
+
+// [core::slice::index::usize::index_mut]: forward function
+let core_slice_index_usize_index_mut (t : Type0) : usize → slice t → result t =
+  admit () // TODO
+
+// [core::slice::index::usize::index_mut]: backward function 0
+let core_slice_index_usize_index_mut_back
+  (t : Type0) : usize → slice t → t → result (slice t) =
+  admit () // TODO
+
+// Trait implementation: [core::slice::index::private_slice_index::usize]
+let core_slice_index_private_slice_index_SealedUsizeInst
+  : core_slice_index_private_slice_index_Sealed usize = ()
+
+// Trait implementation: [core::slice::index::usize]
+let core_slice_index_SliceIndexUsizeSliceTInst (t : Type0) :
+  core_slice_index_SliceIndex usize (slice t) = {
+  sealedInst = core_slice_index_private_slice_index_SealedUsizeInst;
+  output = t;
+  get = core_slice_index_usize_get t;
+  get_mut = core_slice_index_usize_get_mut t;
+  get_mut_back = core_slice_index_usize_get_mut_back t;
+  get_unchecked = core_slice_index_usize_get_unchecked t;
+  get_unchecked_mut = core_slice_index_usize_get_unchecked_mut t;
+  index = core_slice_index_usize_index t;
+  index_mut = core_slice_index_usize_index_mut t;
+  index_mut_back = core_slice_index_usize_index_mut_back t;
+}
+
+// [alloc::vec::Vec::index]: forward function
+let alloc_vec_Vec_index (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (self : alloc_vec_Vec t) (i : idx) : result inst.output =
+  admit () // TODO
+
+// [alloc::vec::Vec::index_mut]: forward function
+let alloc_vec_Vec_index_mut (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (self : alloc_vec_Vec t) (i : idx) : result inst.output =
+  admit () // TODO
+
+// [alloc::vec::Vec::index_mut]: backward function 0
+let alloc_vec_Vec_index_mut_back
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (self : alloc_vec_Vec t) (i : idx) (x : inst.output) : result (alloc_vec_Vec t) =
+  admit () // TODO
+
+// Trait implementation: [alloc::vec::Vec]
+let alloc_vec_Vec_coreopsindexIndexInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_Index (alloc_vec_Vec t) idx = {
+  output = inst.output;
+  index = alloc_vec_Vec_index t idx inst;
+}
+
+// Trait implementation: [alloc::vec::Vec]
+let alloc_vec_Vec_coreopsindexIndexMutInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_IndexMut (alloc_vec_Vec t) idx = {
+  indexInst = alloc_vec_Vec_coreopsindexIndexInst t idx inst;
+  index_mut = alloc_vec_Vec_index_mut t idx inst;
+  index_mut_back = alloc_vec_Vec_index_mut_back t idx inst;
+}
+
+(*** Theorems *)
+
+let alloc_vec_Vec_index_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
+  Lemma (
+    alloc_vec_Vec_index a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i ==
+      alloc_vec_Vec_index_usize v i)
+  [SMTPat (alloc_vec_Vec_index a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i)]
+  =
+  admit()
+
+let alloc_vec_Vec_index_mut_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
+  Lemma (
+    alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i ==
+      alloc_vec_Vec_index_usize v i)
+  [SMTPat (alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i)]
+  =
+  admit()
+
+let alloc_vec_Vec_index_mut_back_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) :
+  Lemma (
+    alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x ==
+      alloc_vec_Vec_update_usize v i x)
+  [SMTPat (alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x)]
+  =
+  admit()
diff --git a/tests/fstar-split/betree/BetreeMain.Clauses.Template.fst b/tests/fstar-split/betree/BetreeMain.Clauses.Template.fst
new file mode 100644
index 00000000..537705c5
--- /dev/null
+++ b/tests/fstar-split/betree/BetreeMain.Clauses.Template.fst
@@ -0,0 +1,117 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [betree_main]: templates for the decreases clauses *)
+module BetreeMain.Clauses.Template
+open Primitives
+open BetreeMain.Types
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [betree_main::betree::{betree_main::betree::List<T>#1}::len]: decreases clause
+    Source: 'src/betree.rs', lines 276:4-276:24 *)
+unfold
+let betree_List_len_decreases (t : Type0) (self : betree_List_t t) : nat =
+  admit ()
+
+(** [betree_main::betree::{betree_main::betree::List<T>#1}::split_at]: decreases clause
+    Source: 'src/betree.rs', lines 284:4-284:51 *)
+unfold
+let betree_List_split_at_decreases (t : Type0) (self : betree_List_t t)
+  (n : u64) : nat =
+  admit ()
+
+(** [betree_main::betree::{betree_main::betree::List<(u64, T)>#2}::partition_at_pivot]: decreases clause
+    Source: 'src/betree.rs', lines 339:4-339:73 *)
+unfold
+let betree_ListTupleU64T_partition_at_pivot_decreases (t : Type0)
+  (self : betree_List_t (u64 & t)) (pivot : u64) : nat =
+  admit ()
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_first_message_for_key]: decreases clause
+    Source: 'src/betree.rs', lines 789:4-792:34 *)
+unfold
+let betree_Node_lookup_first_message_for_key_decreases (key : u64)
+  (msgs : betree_List_t (u64 & betree_Message_t)) : nat =
+  admit ()
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_in_bindings]: decreases clause
+    Source: 'src/betree.rs', lines 636:4-636:80 *)
+unfold
+let betree_Node_lookup_in_bindings_decreases (key : u64)
+  (bindings : betree_List_t (u64 & u64)) : nat =
+  admit ()
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_upserts]: decreases clause
+    Source: 'src/betree.rs', lines 819:4-819:90 *)
+unfold
+let betree_Node_apply_upserts_decreases
+  (msgs : betree_List_t (u64 & betree_Message_t)) (prev : option u64)
+  (key : u64) (st : state) : nat =
+  admit ()
+
+(** [betree_main::betree::{betree_main::betree::Internal#4}::lookup_in_children]: decreases clause
+    Source: 'src/betree.rs', lines 395:4-395:63 *)
+unfold
+let betree_Internal_lookup_in_children_decreases (self : betree_Internal_t)
+  (key : u64) (st : state) : nat =
+  admit ()
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup]: decreases clause
+    Source: 'src/betree.rs', lines 709:4-709:58 *)
+unfold
+let betree_Node_lookup_decreases (self : betree_Node_t) (key : u64)
+  (st : state) : nat =
+  admit ()
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::filter_messages_for_key]: decreases clause
+    Source: 'src/betree.rs', lines 674:4-674:77 *)
+unfold
+let betree_Node_filter_messages_for_key_decreases (key : u64)
+  (msgs : betree_List_t (u64 & betree_Message_t)) : nat =
+  admit ()
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_first_message_after_key]: decreases clause
+    Source: 'src/betree.rs', lines 689:4-692:34 *)
+unfold
+let betree_Node_lookup_first_message_after_key_decreases (key : u64)
+  (msgs : betree_List_t (u64 & betree_Message_t)) : nat =
+  admit ()
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages_to_internal]: decreases clause
+    Source: 'src/betree.rs', lines 502:4-505:5 *)
+unfold
+let betree_Node_apply_messages_to_internal_decreases
+  (msgs : betree_List_t (u64 & betree_Message_t))
+  (new_msgs : betree_List_t (u64 & betree_Message_t)) : nat =
+  admit ()
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_mut_in_bindings]: decreases clause
+    Source: 'src/betree.rs', lines 653:4-656:32 *)
+unfold
+let betree_Node_lookup_mut_in_bindings_decreases (key : u64)
+  (bindings : betree_List_t (u64 & u64)) : nat =
+  admit ()
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages_to_leaf]: decreases clause
+    Source: 'src/betree.rs', lines 444:4-447:5 *)
+unfold
+let betree_Node_apply_messages_to_leaf_decreases
+  (bindings : betree_List_t (u64 & u64))
+  (new_msgs : betree_List_t (u64 & betree_Message_t)) : nat =
+  admit ()
+
+(** [betree_main::betree::{betree_main::betree::Internal#4}::flush]: decreases clause
+    Source: 'src/betree.rs', lines 410:4-415:26 *)
+unfold
+let betree_Internal_flush_decreases (self : betree_Internal_t)
+  (params : betree_Params_t) (node_id_cnt : betree_NodeIdCounter_t)
+  (content : betree_List_t (u64 & betree_Message_t)) (st : state) : nat =
+  admit ()
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages]: decreases clause
+    Source: 'src/betree.rs', lines 588:4-593:5 *)
+unfold
+let betree_Node_apply_messages_decreases (self : betree_Node_t)
+  (params : betree_Params_t) (node_id_cnt : betree_NodeIdCounter_t)
+  (msgs : betree_List_t (u64 & betree_Message_t)) (st : state) : nat =
+  admit ()
+
diff --git a/tests/fstar-split/betree/BetreeMain.Clauses.fst b/tests/fstar-split/betree/BetreeMain.Clauses.fst
new file mode 100644
index 00000000..21f953d1
--- /dev/null
+++ b/tests/fstar-split/betree/BetreeMain.Clauses.fst
@@ -0,0 +1,210 @@
+(** [betree_main]: templates for the decreases clauses *)
+module BetreeMain.Clauses
+open Primitives
+open BetreeMain.Types
+
+#set-options "--z3rlimit 50 --fuel 0 --ifuel 1"
+
+(*** Well-founded relations *)
+
+(* We had a few issues when proving termination of the mutually recursive functions:
+ * - betree_Internal_flush
+ * - betree_Node_apply_messages
+ *
+ * The quantity which effectively decreases is:
+ *   (betree_size, messages_length)
+ *   where messages_length is 0 when there are no messages
+ *   (and where we use the lexicographic ordering, of course)
+ *
+ * However, the `%[...]` and `{:well-founded ...} notations are not available outside
+ * of `decrease` clauses.
+ * 
+ * We thus resorted to writing and proving correct a well-founded relation over
+ * pairs of natural numbers. The trick is that `<<` can be used outside of decrease
+ * clauses, and can be used to trigger SMT patterns.
+ *
+ * What follows is adapted from:
+ * https://www.fstar-lang.org/tutorial/book/part2/part2_well_founded.html
+ *
+ * Also, the following PR might make things easier:
+ * https://github.com/FStarLang/FStar/pull/2561
+ *)
+
+module P = FStar.Preorder
+module W = FStar.WellFounded
+module L = FStar.LexicographicOrdering
+
+let lt_nat (x y:nat) : Type = x < y == true
+let rec wf_lt_nat (x:nat)
+  : W.acc lt_nat x
+  = W.AccIntro (fun y _ -> wf_lt_nat y)
+
+// A type abbreviation for a pair of nats
+let nat_pair = (x:nat & nat)
+
+// Making a lexicographic ordering from a pair of nat ordering
+let lex_order_nat_pair  : P.relation nat_pair =
+  L.lex_t lt_nat (fun _ -> lt_nat)
+
+// The lex order on nat pairs is well-founded, using our general proof
+// of lexicographic composition of well-founded orders
+let lex_order_nat_pair_wf : W.well_founded lex_order_nat_pair =
+  L.lex_t_wf wf_lt_nat (fun _ -> wf_lt_nat)
+
+// A utility to introduce lt_nat
+let mk_lt_nat (x:nat) (y:nat { x < y }) : lt_nat x y =
+  let _ : equals (x < y) true = Refl in
+  ()
+    
+// A utility to make a lex ordering of nat pairs
+let mk_lex_order_nat_pair (xy0:nat_pair) 
+                          (xy1:nat_pair {
+                            let (|x0, y0|) = xy0 in
+                            let (|x1, y1|) = xy1 in
+                            x0 < x1 \/ (x0 == x1 /\ y0 < y1)
+                          }) : lex_order_nat_pair xy0 xy1 =
+  let (|x0, y0|) = xy0 in
+  let (|x1, y1|) = xy1 in
+  if x0 < x1 then L.Left_lex x0 x1 y0 y1 (mk_lt_nat x0 x1)
+  else L.Right_lex x0 y0 y1 (mk_lt_nat y0 y1)
+
+let rec coerce #a #r #x (p:W.acc #a r x) : Tot (W.acc r x) (decreases p) =
+  W.AccIntro (fun y r -> coerce (p.access_smaller y r))
+
+let coerce_wf #a #r (p: (x:a -> W.acc r x)) : x:a -> W.acc r x =
+  fun x -> coerce (p x)
+
+(* We need this axiom, which comes from the following discussion:
+ * https://github.com/FStarLang/FStar/issues/1916
+ * An issue here is that the `{well-founded ... }` notation
+ *)
+assume
+val axiom_well_founded (a : Type) (rel : a -> a -> Type0)
+  (rwf : W.well_founded #a rel) (x y : a) :
+  Lemma (requires (rel x y)) (ensures (x << y))
+
+(* This lemma has a pattern (which makes it work) *)
+let wf_nat_pair_lem (p0 p1 : nat_pair) :
+  Lemma
+  (requires (
+    let (|x0, y0|) = p0 in
+    let (|x1, y1|) = p1 in
+    x0 < x1 || (x0 = x1 && y0 < y1)))
+  (ensures (p0 << p1))
+  [SMTPat (p0 << p1)] =
+  let rel = lex_order_nat_pair in
+  let rel_wf = lex_order_nat_pair_wf in
+  let _ = mk_lex_order_nat_pair p0 p1 in
+  assert(rel p0 p1);
+  axiom_well_founded nat_pair rel rel_wf p0 p1
+
+(*** Decrease clauses *)
+/// "Standard" decrease clauses
+
+(** [betree_main::betree::List::{1}::len]: decreases clause *)
+unfold
+let betree_List_len_decreases (t : Type0) (self : betree_List_t t) : betree_List_t t =
+  self
+
+(** [betree_main::betree::List::{1}::split_at]: decreases clause *)
+unfold
+let betree_List_split_at_decreases (t : Type0) (self : betree_List_t t)
+  (n : u64) : nat =
+  n
+
+(** [betree_main::betree::List::{2}::partition_at_pivot]: decreases clause *)
+unfold
+let betree_ListTupleU64T_partition_at_pivot_decreases (t : Type0)
+  (self : betree_List_t (u64 & t)) (pivot : u64) : betree_List_t (u64 & t) =
+  self
+
+(** [betree_main::betree::Node::{5}::lookup_in_bindings]: decreases clause *)
+unfold
+let betree_Node_lookup_in_bindings_decreases (key : u64)
+  (bindings : betree_List_t (u64 & u64)) : betree_List_t (u64 & u64) =
+  bindings
+
+(** [betree_main::betree::Node::{5}::lookup_first_message_for_key]: decreases clause *)
+unfold
+let betree_Node_lookup_first_message_for_key_decreases (key : u64)
+  (msgs : betree_List_t (u64 & betree_Message_t)) : betree_List_t (u64 & betree_Message_t) =
+  msgs
+
+(** [betree_main::betree::Node::{5}::apply_upserts]: decreases clause *)
+unfold
+let betree_Node_apply_upserts_decreases
+  (msgs : betree_List_t (u64 & betree_Message_t)) (prev : option u64)
+  (key : u64) (st : state) : betree_List_t (u64 & betree_Message_t) =
+  msgs
+
+(** [betree_main::betree::Internal::{4}::lookup_in_children]: decreases clause *)
+unfold
+let betree_Internal_lookup_in_children_decreases (self : betree_Internal_t)
+  (key : u64) (st : state) : betree_Internal_t =
+  self
+
+(** [betree_main::betree::Node::{5}::lookup]: decreases clause *)
+unfold
+let betree_Node_lookup_decreases (self : betree_Node_t) (key : u64)
+  (st : state) : betree_Node_t =
+  self
+
+(** [betree_main::betree::Node::{5}::lookup_mut_in_bindings]: decreases clause *)
+unfold
+let betree_Node_lookup_mut_in_bindings_decreases (key : u64)
+  (bindings : betree_List_t (u64 & u64)) : betree_List_t (u64 & u64) =
+  bindings
+
+unfold
+let betree_Node_apply_messages_to_leaf_decreases
+  (bindings : betree_List_t (u64 & u64))
+  (new_msgs : betree_List_t (u64 & betree_Message_t)) : betree_List_t (u64 & betree_Message_t) =
+  new_msgs
+
+(** [betree_main::betree::Node::{5}::filter_messages_for_key]: decreases clause *)
+unfold
+let betree_Node_filter_messages_for_key_decreases (key : u64)
+  (msgs : betree_List_t (u64 & betree_Message_t)) : betree_List_t (u64 & betree_Message_t) =
+  msgs
+
+(** [betree_main::betree::Node::{5}::lookup_first_message_after_key]: decreases clause *)
+unfold
+let betree_Node_lookup_first_message_after_key_decreases (key : u64)
+  (msgs : betree_List_t (u64 & betree_Message_t)) : betree_List_t (u64 & betree_Message_t) =
+  msgs
+
+let betree_Node_apply_messages_to_internal_decreases
+  (msgs : betree_List_t (u64 & betree_Message_t))
+  (new_msgs : betree_List_t (u64 & betree_Message_t)) : betree_List_t (u64 & betree_Message_t) =
+  new_msgs
+
+(*** Decrease clauses - nat_pair *)
+/// The following decrease clauses use the [nat_pair] definition and the well-founded
+/// relation proven above.
+
+let rec betree_size (bt : betree_Node_t) : nat =
+  match bt with
+  | Betree_Node_Internal node -> 1 + betree_Internal_size node
+  | Betree_Node_Leaf _ -> 1
+
+and betree_Internal_size (node : betree_Internal_t) : nat =
+  1 + betree_size node.left + betree_size node.right
+
+let rec betree_List_len (#a : Type0) (ls : betree_List_t a) : nat =
+  match ls with
+  | Betree_List_Cons _ tl -> 1 + betree_List_len tl
+  | Betree_List_Nil -> 0
+
+(** [betree_main::betree::Internal::{4}::flush]: decreases clause *)
+unfold
+let betree_Internal_flush_decreases (self : betree_Internal_t)
+  (params : betree_Params_t) (node_id_cnt : betree_NodeIdCounter_t)
+  (content : betree_List_t (u64 & betree_Message_t)) (st : state) : nat_pair =
+  (|betree_Internal_size self, 0|)
+
+(** [betree_main::betree::Node::{5}::apply_messages]: decreases clause *)
+unfold
+let betree_Node_apply_messages_decreases (self : betree_Node_t)
+  (params : betree_Params_t) (node_id_cnt : betree_NodeIdCounter_t)
+  (msgs : betree_List_t (u64 & betree_Message_t)) (st : state) : nat_pair =
+  (|betree_size self, betree_List_len msgs|)
diff --git a/tests/fstar-split/betree/BetreeMain.Funs.fst b/tests/fstar-split/betree/BetreeMain.Funs.fst
new file mode 100644
index 00000000..6890488a
--- /dev/null
+++ b/tests/fstar-split/betree/BetreeMain.Funs.fst
@@ -0,0 +1,1011 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [betree_main]: function definitions *)
+module BetreeMain.Funs
+open Primitives
+include BetreeMain.Types
+include BetreeMain.FunsExternal
+include BetreeMain.Clauses
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [betree_main::betree::load_internal_node]: forward function
+    Source: 'src/betree.rs', lines 36:0-36:52 *)
+let betree_load_internal_node
+  (id : u64) (st : state) :
+  result (state & (betree_List_t (u64 & betree_Message_t)))
+  =
+  betree_utils_load_internal_node id st
+
+(** [betree_main::betree::store_internal_node]: forward function
+    Source: 'src/betree.rs', lines 41:0-41:60 *)
+let betree_store_internal_node
+  (id : u64) (content : betree_List_t (u64 & betree_Message_t)) (st : state) :
+  result (state & unit)
+  =
+  let* (st1, _) = betree_utils_store_internal_node id content st in
+  Return (st1, ())
+
+(** [betree_main::betree::load_leaf_node]: forward function
+    Source: 'src/betree.rs', lines 46:0-46:44 *)
+let betree_load_leaf_node
+  (id : u64) (st : state) : result (state & (betree_List_t (u64 & u64))) =
+  betree_utils_load_leaf_node id st
+
+(** [betree_main::betree::store_leaf_node]: forward function
+    Source: 'src/betree.rs', lines 51:0-51:52 *)
+let betree_store_leaf_node
+  (id : u64) (content : betree_List_t (u64 & u64)) (st : state) :
+  result (state & unit)
+  =
+  let* (st1, _) = betree_utils_store_leaf_node id content st in
+  Return (st1, ())
+
+(** [betree_main::betree::fresh_node_id]: forward function
+    Source: 'src/betree.rs', lines 55:0-55:48 *)
+let betree_fresh_node_id (counter : u64) : result u64 =
+  let* _ = u64_add counter 1 in Return counter
+
+(** [betree_main::betree::fresh_node_id]: backward function 0
+    Source: 'src/betree.rs', lines 55:0-55:48 *)
+let betree_fresh_node_id_back (counter : u64) : result u64 =
+  u64_add counter 1
+
+(** [betree_main::betree::{betree_main::betree::NodeIdCounter}::new]: forward function
+    Source: 'src/betree.rs', lines 206:4-206:20 *)
+let betree_NodeIdCounter_new : result betree_NodeIdCounter_t =
+  Return { next_node_id = 0 }
+
+(** [betree_main::betree::{betree_main::betree::NodeIdCounter}::fresh_id]: forward function
+    Source: 'src/betree.rs', lines 210:4-210:36 *)
+let betree_NodeIdCounter_fresh_id
+  (self : betree_NodeIdCounter_t) : result u64 =
+  let* _ = u64_add self.next_node_id 1 in Return self.next_node_id
+
+(** [betree_main::betree::{betree_main::betree::NodeIdCounter}::fresh_id]: backward function 0
+    Source: 'src/betree.rs', lines 210:4-210:36 *)
+let betree_NodeIdCounter_fresh_id_back
+  (self : betree_NodeIdCounter_t) : result betree_NodeIdCounter_t =
+  let* i = u64_add self.next_node_id 1 in Return { next_node_id = i }
+
+(** [betree_main::betree::upsert_update]: forward function
+    Source: 'src/betree.rs', lines 234:0-234:70 *)
+let betree_upsert_update
+  (prev : option u64) (st : betree_UpsertFunState_t) : result u64 =
+  begin match prev with
+  | None ->
+    begin match st with
+    | Betree_UpsertFunState_Add v -> Return v
+    | Betree_UpsertFunState_Sub _ -> Return 0
+    end
+  | Some prev1 ->
+    begin match st with
+    | Betree_UpsertFunState_Add v ->
+      let* margin = u64_sub core_u64_max prev1 in
+      if margin >= v then u64_add prev1 v else Return core_u64_max
+    | Betree_UpsertFunState_Sub v ->
+      if prev1 >= v then u64_sub prev1 v else Return 0
+    end
+  end
+
+(** [betree_main::betree::{betree_main::betree::List<T>#1}::len]: forward function
+    Source: 'src/betree.rs', lines 276:4-276:24 *)
+let rec betree_List_len
+  (t : Type0) (self : betree_List_t t) :
+  Tot (result u64) (decreases (betree_List_len_decreases t self))
+  =
+  begin match self with
+  | Betree_List_Cons _ tl -> let* i = betree_List_len t tl in u64_add 1 i
+  | Betree_List_Nil -> Return 0
+  end
+
+(** [betree_main::betree::{betree_main::betree::List<T>#1}::split_at]: forward function
+    Source: 'src/betree.rs', lines 284:4-284:51 *)
+let rec betree_List_split_at
+  (t : Type0) (self : betree_List_t t) (n : u64) :
+  Tot (result ((betree_List_t t) & (betree_List_t t)))
+  (decreases (betree_List_split_at_decreases t self n))
+  =
+  if n = 0
+  then Return (Betree_List_Nil, self)
+  else
+    begin match self with
+    | Betree_List_Cons hd tl ->
+      let* i = u64_sub n 1 in
+      let* p = betree_List_split_at t tl i in
+      let (ls0, ls1) = p in
+      let l = ls0 in
+      Return (Betree_List_Cons hd l, ls1)
+    | Betree_List_Nil -> Fail Failure
+    end
+
+(** [betree_main::betree::{betree_main::betree::List<T>#1}::push_front]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/betree.rs', lines 299:4-299:34 *)
+let betree_List_push_front
+  (t : Type0) (self : betree_List_t t) (x : t) : result (betree_List_t t) =
+  let tl = core_mem_replace (betree_List_t t) self Betree_List_Nil in
+  let l = tl in
+  Return (Betree_List_Cons x l)
+
+(** [betree_main::betree::{betree_main::betree::List<T>#1}::pop_front]: forward function
+    Source: 'src/betree.rs', lines 306:4-306:32 *)
+let betree_List_pop_front (t : Type0) (self : betree_List_t t) : result t =
+  let ls = core_mem_replace (betree_List_t t) self Betree_List_Nil in
+  begin match ls with
+  | Betree_List_Cons x _ -> Return x
+  | Betree_List_Nil -> Fail Failure
+  end
+
+(** [betree_main::betree::{betree_main::betree::List<T>#1}::pop_front]: backward function 0
+    Source: 'src/betree.rs', lines 306:4-306:32 *)
+let betree_List_pop_front_back
+  (t : Type0) (self : betree_List_t t) : result (betree_List_t t) =
+  let ls = core_mem_replace (betree_List_t t) self Betree_List_Nil in
+  begin match ls with
+  | Betree_List_Cons _ tl -> Return tl
+  | Betree_List_Nil -> Fail Failure
+  end
+
+(** [betree_main::betree::{betree_main::betree::List<T>#1}::hd]: forward function
+    Source: 'src/betree.rs', lines 318:4-318:22 *)
+let betree_List_hd (t : Type0) (self : betree_List_t t) : result t =
+  begin match self with
+  | Betree_List_Cons hd _ -> Return hd
+  | Betree_List_Nil -> Fail Failure
+  end
+
+(** [betree_main::betree::{betree_main::betree::List<(u64, T)>#2}::head_has_key]: forward function
+    Source: 'src/betree.rs', lines 327:4-327:44 *)
+let betree_ListTupleU64T_head_has_key
+  (t : Type0) (self : betree_List_t (u64 & t)) (key : u64) : result bool =
+  begin match self with
+  | Betree_List_Cons hd _ -> let (i, _) = hd in Return (i = key)
+  | Betree_List_Nil -> Return false
+  end
+
+(** [betree_main::betree::{betree_main::betree::List<(u64, T)>#2}::partition_at_pivot]: forward function
+    Source: 'src/betree.rs', lines 339:4-339:73 *)
+let rec betree_ListTupleU64T_partition_at_pivot
+  (t : Type0) (self : betree_List_t (u64 & t)) (pivot : u64) :
+  Tot (result ((betree_List_t (u64 & t)) & (betree_List_t (u64 & t))))
+  (decreases (betree_ListTupleU64T_partition_at_pivot_decreases t self pivot))
+  =
+  begin match self with
+  | Betree_List_Cons hd tl ->
+    let (i, x) = hd in
+    if i >= pivot
+    then Return (Betree_List_Nil, Betree_List_Cons (i, x) tl)
+    else
+      let* p = betree_ListTupleU64T_partition_at_pivot t tl pivot in
+      let (ls0, ls1) = p in
+      let l = ls0 in
+      Return (Betree_List_Cons (i, x) l, ls1)
+  | Betree_List_Nil -> Return (Betree_List_Nil, Betree_List_Nil)
+  end
+
+(** [betree_main::betree::{betree_main::betree::Leaf#3}::split]: forward function
+    Source: 'src/betree.rs', lines 359:4-364:17 *)
+let betree_Leaf_split
+  (self : betree_Leaf_t) (content : betree_List_t (u64 & u64))
+  (params : betree_Params_t) (node_id_cnt : betree_NodeIdCounter_t)
+  (st : state) :
+  result (state & betree_Internal_t)
+  =
+  let* p = betree_List_split_at (u64 & u64) content params.split_size in
+  let (content0, content1) = p in
+  let* p1 = betree_List_hd (u64 & u64) content1 in
+  let (pivot, _) = p1 in
+  let* id0 = betree_NodeIdCounter_fresh_id node_id_cnt in
+  let* node_id_cnt1 = betree_NodeIdCounter_fresh_id_back node_id_cnt in
+  let* id1 = betree_NodeIdCounter_fresh_id node_id_cnt1 in
+  let* (st1, _) = betree_store_leaf_node id0 content0 st in
+  let* (st2, _) = betree_store_leaf_node id1 content1 st1 in
+  let n = Betree_Node_Leaf { id = id0; size = params.split_size } in
+  let n1 = Betree_Node_Leaf { id = id1; size = params.split_size } in
+  Return (st2, { id = self.id; pivot = pivot; left = n; right = n1 })
+
+(** [betree_main::betree::{betree_main::betree::Leaf#3}::split]: backward function 2
+    Source: 'src/betree.rs', lines 359:4-364:17 *)
+let betree_Leaf_split_back
+  (self : betree_Leaf_t) (content : betree_List_t (u64 & u64))
+  (params : betree_Params_t) (node_id_cnt : betree_NodeIdCounter_t)
+  (st : state) :
+  result betree_NodeIdCounter_t
+  =
+  let* p = betree_List_split_at (u64 & u64) content params.split_size in
+  let (content0, content1) = p in
+  let* _ = betree_List_hd (u64 & u64) content1 in
+  let* id0 = betree_NodeIdCounter_fresh_id node_id_cnt in
+  let* node_id_cnt1 = betree_NodeIdCounter_fresh_id_back node_id_cnt in
+  let* id1 = betree_NodeIdCounter_fresh_id node_id_cnt1 in
+  let* (st1, _) = betree_store_leaf_node id0 content0 st in
+  let* _ = betree_store_leaf_node id1 content1 st1 in
+  betree_NodeIdCounter_fresh_id_back node_id_cnt1
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_first_message_for_key]: forward function
+    Source: 'src/betree.rs', lines 789:4-792:34 *)
+let rec betree_Node_lookup_first_message_for_key
+  (key : u64) (msgs : betree_List_t (u64 & betree_Message_t)) :
+  Tot (result (betree_List_t (u64 & betree_Message_t)))
+  (decreases (betree_Node_lookup_first_message_for_key_decreases key msgs))
+  =
+  begin match msgs with
+  | Betree_List_Cons x next_msgs ->
+    let (i, m) = x in
+    if i >= key
+    then Return (Betree_List_Cons (i, m) next_msgs)
+    else betree_Node_lookup_first_message_for_key key next_msgs
+  | Betree_List_Nil -> Return Betree_List_Nil
+  end
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_first_message_for_key]: backward function 0
+    Source: 'src/betree.rs', lines 789:4-792:34 *)
+let rec betree_Node_lookup_first_message_for_key_back
+  (key : u64) (msgs : betree_List_t (u64 & betree_Message_t))
+  (ret : betree_List_t (u64 & betree_Message_t)) :
+  Tot (result (betree_List_t (u64 & betree_Message_t)))
+  (decreases (betree_Node_lookup_first_message_for_key_decreases key msgs))
+  =
+  begin match msgs with
+  | Betree_List_Cons x next_msgs ->
+    let (i, m) = x in
+    if i >= key
+    then Return ret
+    else
+      let* next_msgs1 =
+        betree_Node_lookup_first_message_for_key_back key next_msgs ret in
+      Return (Betree_List_Cons (i, m) next_msgs1)
+  | Betree_List_Nil -> Return ret
+  end
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_in_bindings]: forward function
+    Source: 'src/betree.rs', lines 636:4-636:80 *)
+let rec betree_Node_lookup_in_bindings
+  (key : u64) (bindings : betree_List_t (u64 & u64)) :
+  Tot (result (option u64))
+  (decreases (betree_Node_lookup_in_bindings_decreases key bindings))
+  =
+  begin match bindings with
+  | Betree_List_Cons hd tl ->
+    let (i, i1) = hd in
+    if i = key
+    then Return (Some i1)
+    else if i > key then Return None else betree_Node_lookup_in_bindings key tl
+  | Betree_List_Nil -> Return None
+  end
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_upserts]: forward function
+    Source: 'src/betree.rs', lines 819:4-819:90 *)
+let rec betree_Node_apply_upserts
+  (msgs : betree_List_t (u64 & betree_Message_t)) (prev : option u64)
+  (key : u64) (st : state) :
+  Tot (result (state & u64))
+  (decreases (betree_Node_apply_upserts_decreases msgs prev key st))
+  =
+  let* b = betree_ListTupleU64T_head_has_key betree_Message_t msgs key in
+  if b
+  then
+    let* msg = betree_List_pop_front (u64 & betree_Message_t) msgs in
+    let (_, m) = msg in
+    begin match m with
+    | Betree_Message_Insert _ -> Fail Failure
+    | Betree_Message_Delete -> Fail Failure
+    | Betree_Message_Upsert s ->
+      let* v = betree_upsert_update prev s in
+      let* msgs1 = betree_List_pop_front_back (u64 & betree_Message_t) msgs in
+      betree_Node_apply_upserts msgs1 (Some v) key st
+    end
+  else
+    let* (st1, v) = core_option_Option_unwrap u64 prev st in
+    let* _ =
+      betree_List_push_front (u64 & betree_Message_t) msgs (key,
+        Betree_Message_Insert v) in
+    Return (st1, v)
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_upserts]: backward function 0
+    Source: 'src/betree.rs', lines 819:4-819:90 *)
+let rec betree_Node_apply_upserts_back
+  (msgs : betree_List_t (u64 & betree_Message_t)) (prev : option u64)
+  (key : u64) (st : state) :
+  Tot (result (betree_List_t (u64 & betree_Message_t)))
+  (decreases (betree_Node_apply_upserts_decreases msgs prev key st))
+  =
+  let* b = betree_ListTupleU64T_head_has_key betree_Message_t msgs key in
+  if b
+  then
+    let* msg = betree_List_pop_front (u64 & betree_Message_t) msgs in
+    let (_, m) = msg in
+    begin match m with
+    | Betree_Message_Insert _ -> Fail Failure
+    | Betree_Message_Delete -> Fail Failure
+    | Betree_Message_Upsert s ->
+      let* v = betree_upsert_update prev s in
+      let* msgs1 = betree_List_pop_front_back (u64 & betree_Message_t) msgs in
+      betree_Node_apply_upserts_back msgs1 (Some v) key st
+    end
+  else
+    let* (_, v) = core_option_Option_unwrap u64 prev st in
+    betree_List_push_front (u64 & betree_Message_t) msgs (key,
+      Betree_Message_Insert v)
+
+(** [betree_main::betree::{betree_main::betree::Internal#4}::lookup_in_children]: forward function
+    Source: 'src/betree.rs', lines 395:4-395:63 *)
+let rec betree_Internal_lookup_in_children
+  (self : betree_Internal_t) (key : u64) (st : state) :
+  Tot (result (state & (option u64)))
+  (decreases (betree_Internal_lookup_in_children_decreases self key st))
+  =
+  if key < self.pivot
+  then betree_Node_lookup self.left key st
+  else betree_Node_lookup self.right key st
+
+(** [betree_main::betree::{betree_main::betree::Internal#4}::lookup_in_children]: backward function 0
+    Source: 'src/betree.rs', lines 395:4-395:63 *)
+and betree_Internal_lookup_in_children_back
+  (self : betree_Internal_t) (key : u64) (st : state) :
+  Tot (result betree_Internal_t)
+  (decreases (betree_Internal_lookup_in_children_decreases self key st))
+  =
+  if key < self.pivot
+  then
+    let* n = betree_Node_lookup_back self.left key st in
+    Return { self with left = n }
+  else
+    let* n = betree_Node_lookup_back self.right key st in
+    Return { self with right = n }
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup]: forward function
+    Source: 'src/betree.rs', lines 709:4-709:58 *)
+and betree_Node_lookup
+  (self : betree_Node_t) (key : u64) (st : state) :
+  Tot (result (state & (option u64)))
+  (decreases (betree_Node_lookup_decreases self key st))
+  =
+  begin match self with
+  | Betree_Node_Internal node ->
+    let* (st1, msgs) = betree_load_internal_node node.id st in
+    let* pending = betree_Node_lookup_first_message_for_key key msgs in
+    begin match pending with
+    | Betree_List_Cons p l ->
+      let (k, msg) = p in
+      if k <> key
+      then
+        let* (st2, o) = betree_Internal_lookup_in_children node key st1 in
+        let* _ =
+          betree_Node_lookup_first_message_for_key_back key msgs
+            (Betree_List_Cons (k, msg) l) in
+        Return (st2, o)
+      else
+        begin match msg with
+        | Betree_Message_Insert v ->
+          let* _ =
+            betree_Node_lookup_first_message_for_key_back key msgs
+              (Betree_List_Cons (k, Betree_Message_Insert v) l) in
+          Return (st1, Some v)
+        | Betree_Message_Delete ->
+          let* _ =
+            betree_Node_lookup_first_message_for_key_back key msgs
+              (Betree_List_Cons (k, Betree_Message_Delete) l) in
+          Return (st1, None)
+        | Betree_Message_Upsert ufs ->
+          let* (st2, v) = betree_Internal_lookup_in_children node key st1 in
+          let* (st3, v1) =
+            betree_Node_apply_upserts (Betree_List_Cons (k,
+              Betree_Message_Upsert ufs) l) v key st2 in
+          let* node1 = betree_Internal_lookup_in_children_back node key st1 in
+          let* pending1 =
+            betree_Node_apply_upserts_back (Betree_List_Cons (k,
+              Betree_Message_Upsert ufs) l) v key st2 in
+          let* msgs1 =
+            betree_Node_lookup_first_message_for_key_back key msgs pending1 in
+          let* (st4, _) = betree_store_internal_node node1.id msgs1 st3 in
+          Return (st4, Some v1)
+        end
+    | Betree_List_Nil ->
+      let* (st2, o) = betree_Internal_lookup_in_children node key st1 in
+      let* _ =
+        betree_Node_lookup_first_message_for_key_back key msgs Betree_List_Nil
+        in
+      Return (st2, o)
+    end
+  | Betree_Node_Leaf node ->
+    let* (st1, bindings) = betree_load_leaf_node node.id st in
+    let* o = betree_Node_lookup_in_bindings key bindings in
+    Return (st1, o)
+  end
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup]: backward function 0
+    Source: 'src/betree.rs', lines 709:4-709:58 *)
+and betree_Node_lookup_back
+  (self : betree_Node_t) (key : u64) (st : state) :
+  Tot (result betree_Node_t)
+  (decreases (betree_Node_lookup_decreases self key st))
+  =
+  begin match self with
+  | Betree_Node_Internal node ->
+    let* (st1, msgs) = betree_load_internal_node node.id st in
+    let* pending = betree_Node_lookup_first_message_for_key key msgs in
+    begin match pending with
+    | Betree_List_Cons p l ->
+      let (k, msg) = p in
+      if k <> key
+      then
+        let* _ =
+          betree_Node_lookup_first_message_for_key_back key msgs
+            (Betree_List_Cons (k, msg) l) in
+        let* node1 = betree_Internal_lookup_in_children_back node key st1 in
+        Return (Betree_Node_Internal node1)
+      else
+        begin match msg with
+        | Betree_Message_Insert v ->
+          let* _ =
+            betree_Node_lookup_first_message_for_key_back key msgs
+              (Betree_List_Cons (k, Betree_Message_Insert v) l) in
+          Return (Betree_Node_Internal node)
+        | Betree_Message_Delete ->
+          let* _ =
+            betree_Node_lookup_first_message_for_key_back key msgs
+              (Betree_List_Cons (k, Betree_Message_Delete) l) in
+          Return (Betree_Node_Internal node)
+        | Betree_Message_Upsert ufs ->
+          let* (st2, v) = betree_Internal_lookup_in_children node key st1 in
+          let* (st3, _) =
+            betree_Node_apply_upserts (Betree_List_Cons (k,
+              Betree_Message_Upsert ufs) l) v key st2 in
+          let* node1 = betree_Internal_lookup_in_children_back node key st1 in
+          let* pending1 =
+            betree_Node_apply_upserts_back (Betree_List_Cons (k,
+              Betree_Message_Upsert ufs) l) v key st2 in
+          let* msgs1 =
+            betree_Node_lookup_first_message_for_key_back key msgs pending1 in
+          let* _ = betree_store_internal_node node1.id msgs1 st3 in
+          Return (Betree_Node_Internal node1)
+        end
+    | Betree_List_Nil ->
+      let* _ =
+        betree_Node_lookup_first_message_for_key_back key msgs Betree_List_Nil
+        in
+      let* node1 = betree_Internal_lookup_in_children_back node key st1 in
+      Return (Betree_Node_Internal node1)
+    end
+  | Betree_Node_Leaf node ->
+    let* (_, bindings) = betree_load_leaf_node node.id st in
+    let* _ = betree_Node_lookup_in_bindings key bindings in
+    Return (Betree_Node_Leaf node)
+  end
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::filter_messages_for_key]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/betree.rs', lines 674:4-674:77 *)
+let rec betree_Node_filter_messages_for_key
+  (key : u64) (msgs : betree_List_t (u64 & betree_Message_t)) :
+  Tot (result (betree_List_t (u64 & betree_Message_t)))
+  (decreases (betree_Node_filter_messages_for_key_decreases key msgs))
+  =
+  begin match msgs with
+  | Betree_List_Cons p l ->
+    let (k, m) = p in
+    if k = key
+    then
+      let* msgs1 =
+        betree_List_pop_front_back (u64 & betree_Message_t) (Betree_List_Cons
+          (k, m) l) in
+      betree_Node_filter_messages_for_key key msgs1
+    else Return (Betree_List_Cons (k, m) l)
+  | Betree_List_Nil -> Return Betree_List_Nil
+  end
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_first_message_after_key]: forward function
+    Source: 'src/betree.rs', lines 689:4-692:34 *)
+let rec betree_Node_lookup_first_message_after_key
+  (key : u64) (msgs : betree_List_t (u64 & betree_Message_t)) :
+  Tot (result (betree_List_t (u64 & betree_Message_t)))
+  (decreases (betree_Node_lookup_first_message_after_key_decreases key msgs))
+  =
+  begin match msgs with
+  | Betree_List_Cons p next_msgs ->
+    let (k, m) = p in
+    if k = key
+    then betree_Node_lookup_first_message_after_key key next_msgs
+    else Return (Betree_List_Cons (k, m) next_msgs)
+  | Betree_List_Nil -> Return Betree_List_Nil
+  end
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_first_message_after_key]: backward function 0
+    Source: 'src/betree.rs', lines 689:4-692:34 *)
+let rec betree_Node_lookup_first_message_after_key_back
+  (key : u64) (msgs : betree_List_t (u64 & betree_Message_t))
+  (ret : betree_List_t (u64 & betree_Message_t)) :
+  Tot (result (betree_List_t (u64 & betree_Message_t)))
+  (decreases (betree_Node_lookup_first_message_after_key_decreases key msgs))
+  =
+  begin match msgs with
+  | Betree_List_Cons p next_msgs ->
+    let (k, m) = p in
+    if k = key
+    then
+      let* next_msgs1 =
+        betree_Node_lookup_first_message_after_key_back key next_msgs ret in
+      Return (Betree_List_Cons (k, m) next_msgs1)
+    else Return ret
+  | Betree_List_Nil -> Return ret
+  end
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_to_internal]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/betree.rs', lines 521:4-521:89 *)
+let betree_Node_apply_to_internal
+  (msgs : betree_List_t (u64 & betree_Message_t)) (key : u64)
+  (new_msg : betree_Message_t) :
+  result (betree_List_t (u64 & betree_Message_t))
+  =
+  let* msgs1 = betree_Node_lookup_first_message_for_key key msgs in
+  let* b = betree_ListTupleU64T_head_has_key betree_Message_t msgs1 key in
+  if b
+  then
+    begin match new_msg with
+    | Betree_Message_Insert i ->
+      let* msgs2 = betree_Node_filter_messages_for_key key msgs1 in
+      let* msgs3 =
+        betree_List_push_front (u64 & betree_Message_t) msgs2 (key,
+          Betree_Message_Insert i) in
+      betree_Node_lookup_first_message_for_key_back key msgs msgs3
+    | Betree_Message_Delete ->
+      let* msgs2 = betree_Node_filter_messages_for_key key msgs1 in
+      let* msgs3 =
+        betree_List_push_front (u64 & betree_Message_t) msgs2 (key,
+          Betree_Message_Delete) in
+      betree_Node_lookup_first_message_for_key_back key msgs msgs3
+    | Betree_Message_Upsert s ->
+      let* p = betree_List_hd (u64 & betree_Message_t) msgs1 in
+      let (_, m) = p in
+      begin match m with
+      | Betree_Message_Insert prev ->
+        let* v = betree_upsert_update (Some prev) s in
+        let* msgs2 = betree_List_pop_front_back (u64 & betree_Message_t) msgs1
+          in
+        let* msgs3 =
+          betree_List_push_front (u64 & betree_Message_t) msgs2 (key,
+            Betree_Message_Insert v) in
+        betree_Node_lookup_first_message_for_key_back key msgs msgs3
+      | Betree_Message_Delete ->
+        let* v = betree_upsert_update None s in
+        let* msgs2 = betree_List_pop_front_back (u64 & betree_Message_t) msgs1
+          in
+        let* msgs3 =
+          betree_List_push_front (u64 & betree_Message_t) msgs2 (key,
+            Betree_Message_Insert v) in
+        betree_Node_lookup_first_message_for_key_back key msgs msgs3
+      | Betree_Message_Upsert _ ->
+        let* msgs2 = betree_Node_lookup_first_message_after_key key msgs1 in
+        let* msgs3 =
+          betree_List_push_front (u64 & betree_Message_t) msgs2 (key,
+            Betree_Message_Upsert s) in
+        let* msgs4 =
+          betree_Node_lookup_first_message_after_key_back key msgs1 msgs3 in
+        betree_Node_lookup_first_message_for_key_back key msgs msgs4
+      end
+    end
+  else
+    let* msgs2 =
+      betree_List_push_front (u64 & betree_Message_t) msgs1 (key, new_msg) in
+    betree_Node_lookup_first_message_for_key_back key msgs msgs2
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages_to_internal]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/betree.rs', lines 502:4-505:5 *)
+let rec betree_Node_apply_messages_to_internal
+  (msgs : betree_List_t (u64 & betree_Message_t))
+  (new_msgs : betree_List_t (u64 & betree_Message_t)) :
+  Tot (result (betree_List_t (u64 & betree_Message_t)))
+  (decreases (betree_Node_apply_messages_to_internal_decreases msgs new_msgs))
+  =
+  begin match new_msgs with
+  | Betree_List_Cons new_msg new_msgs_tl ->
+    let (i, m) = new_msg in
+    let* msgs1 = betree_Node_apply_to_internal msgs i m in
+    betree_Node_apply_messages_to_internal msgs1 new_msgs_tl
+  | Betree_List_Nil -> Return msgs
+  end
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_mut_in_bindings]: forward function
+    Source: 'src/betree.rs', lines 653:4-656:32 *)
+let rec betree_Node_lookup_mut_in_bindings
+  (key : u64) (bindings : betree_List_t (u64 & u64)) :
+  Tot (result (betree_List_t (u64 & u64)))
+  (decreases (betree_Node_lookup_mut_in_bindings_decreases key bindings))
+  =
+  begin match bindings with
+  | Betree_List_Cons hd tl ->
+    let (i, i1) = hd in
+    if i >= key
+    then Return (Betree_List_Cons (i, i1) tl)
+    else betree_Node_lookup_mut_in_bindings key tl
+  | Betree_List_Nil -> Return Betree_List_Nil
+  end
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_mut_in_bindings]: backward function 0
+    Source: 'src/betree.rs', lines 653:4-656:32 *)
+let rec betree_Node_lookup_mut_in_bindings_back
+  (key : u64) (bindings : betree_List_t (u64 & u64))
+  (ret : betree_List_t (u64 & u64)) :
+  Tot (result (betree_List_t (u64 & u64)))
+  (decreases (betree_Node_lookup_mut_in_bindings_decreases key bindings))
+  =
+  begin match bindings with
+  | Betree_List_Cons hd tl ->
+    let (i, i1) = hd in
+    if i >= key
+    then Return ret
+    else
+      let* tl1 = betree_Node_lookup_mut_in_bindings_back key tl ret in
+      Return (Betree_List_Cons (i, i1) tl1)
+  | Betree_List_Nil -> Return ret
+  end
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_to_leaf]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/betree.rs', lines 460:4-460:87 *)
+let betree_Node_apply_to_leaf
+  (bindings : betree_List_t (u64 & u64)) (key : u64)
+  (new_msg : betree_Message_t) :
+  result (betree_List_t (u64 & u64))
+  =
+  let* bindings1 = betree_Node_lookup_mut_in_bindings key bindings in
+  let* b = betree_ListTupleU64T_head_has_key u64 bindings1 key in
+  if b
+  then
+    let* hd = betree_List_pop_front (u64 & u64) bindings1 in
+    begin match new_msg with
+    | Betree_Message_Insert v ->
+      let* bindings2 = betree_List_pop_front_back (u64 & u64) bindings1 in
+      let* bindings3 = betree_List_push_front (u64 & u64) bindings2 (key, v) in
+      betree_Node_lookup_mut_in_bindings_back key bindings bindings3
+    | Betree_Message_Delete ->
+      let* bindings2 = betree_List_pop_front_back (u64 & u64) bindings1 in
+      betree_Node_lookup_mut_in_bindings_back key bindings bindings2
+    | Betree_Message_Upsert s ->
+      let (_, i) = hd in
+      let* v = betree_upsert_update (Some i) s in
+      let* bindings2 = betree_List_pop_front_back (u64 & u64) bindings1 in
+      let* bindings3 = betree_List_push_front (u64 & u64) bindings2 (key, v) in
+      betree_Node_lookup_mut_in_bindings_back key bindings bindings3
+    end
+  else
+    begin match new_msg with
+    | Betree_Message_Insert v ->
+      let* bindings2 = betree_List_push_front (u64 & u64) bindings1 (key, v) in
+      betree_Node_lookup_mut_in_bindings_back key bindings bindings2
+    | Betree_Message_Delete ->
+      betree_Node_lookup_mut_in_bindings_back key bindings bindings1
+    | Betree_Message_Upsert s ->
+      let* v = betree_upsert_update None s in
+      let* bindings2 = betree_List_push_front (u64 & u64) bindings1 (key, v) in
+      betree_Node_lookup_mut_in_bindings_back key bindings bindings2
+    end
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages_to_leaf]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/betree.rs', lines 444:4-447:5 *)
+let rec betree_Node_apply_messages_to_leaf
+  (bindings : betree_List_t (u64 & u64))
+  (new_msgs : betree_List_t (u64 & betree_Message_t)) :
+  Tot (result (betree_List_t (u64 & u64)))
+  (decreases (betree_Node_apply_messages_to_leaf_decreases bindings new_msgs))
+  =
+  begin match new_msgs with
+  | Betree_List_Cons new_msg new_msgs_tl ->
+    let (i, m) = new_msg in
+    let* bindings1 = betree_Node_apply_to_leaf bindings i m in
+    betree_Node_apply_messages_to_leaf bindings1 new_msgs_tl
+  | Betree_List_Nil -> Return bindings
+  end
+
+(** [betree_main::betree::{betree_main::betree::Internal#4}::flush]: forward function
+    Source: 'src/betree.rs', lines 410:4-415:26 *)
+let rec betree_Internal_flush
+  (self : betree_Internal_t) (params : betree_Params_t)
+  (node_id_cnt : betree_NodeIdCounter_t)
+  (content : betree_List_t (u64 & betree_Message_t)) (st : state) :
+  Tot (result (state & (betree_List_t (u64 & betree_Message_t))))
+  (decreases (
+    betree_Internal_flush_decreases self params node_id_cnt content st))
+  =
+  let* p =
+    betree_ListTupleU64T_partition_at_pivot betree_Message_t content self.pivot
+    in
+  let (msgs_left, msgs_right) = p in
+  let* len_left = betree_List_len (u64 & betree_Message_t) msgs_left in
+  if len_left >= params.min_flush_size
+  then
+    let* (st1, _) =
+      betree_Node_apply_messages self.left params node_id_cnt msgs_left st in
+    let* (_, node_id_cnt1) =
+      betree_Node_apply_messages_back self.left params node_id_cnt msgs_left st
+      in
+    let* len_right = betree_List_len (u64 & betree_Message_t) msgs_right in
+    if len_right >= params.min_flush_size
+    then
+      let* (st2, _) =
+        betree_Node_apply_messages self.right params node_id_cnt1 msgs_right
+          st1 in
+      let* _ =
+        betree_Node_apply_messages_back self.right params node_id_cnt1
+          msgs_right st1 in
+      Return (st2, Betree_List_Nil)
+    else Return (st1, msgs_right)
+  else
+    let* (st1, _) =
+      betree_Node_apply_messages self.right params node_id_cnt msgs_right st in
+    let* _ =
+      betree_Node_apply_messages_back self.right params node_id_cnt msgs_right
+        st in
+    Return (st1, msgs_left)
+
+(** [betree_main::betree::{betree_main::betree::Internal#4}::flush]: backward function 0
+    Source: 'src/betree.rs', lines 410:4-415:26 *)
+and betree_Internal_flush_back
+  (self : betree_Internal_t) (params : betree_Params_t)
+  (node_id_cnt : betree_NodeIdCounter_t)
+  (content : betree_List_t (u64 & betree_Message_t)) (st : state) :
+  Tot (result (betree_Internal_t & betree_NodeIdCounter_t))
+  (decreases (
+    betree_Internal_flush_decreases self params node_id_cnt content st))
+  =
+  let* p =
+    betree_ListTupleU64T_partition_at_pivot betree_Message_t content self.pivot
+    in
+  let (msgs_left, msgs_right) = p in
+  let* len_left = betree_List_len (u64 & betree_Message_t) msgs_left in
+  if len_left >= params.min_flush_size
+  then
+    let* (st1, _) =
+      betree_Node_apply_messages self.left params node_id_cnt msgs_left st in
+    let* (n, node_id_cnt1) =
+      betree_Node_apply_messages_back self.left params node_id_cnt msgs_left st
+      in
+    let* len_right = betree_List_len (u64 & betree_Message_t) msgs_right in
+    if len_right >= params.min_flush_size
+    then
+      let* (n1, node_id_cnt2) =
+        betree_Node_apply_messages_back self.right params node_id_cnt1
+          msgs_right st1 in
+      Return ({ self with left = n; right = n1 }, node_id_cnt2)
+    else Return ({ self with left = n }, node_id_cnt1)
+  else
+    let* (n, node_id_cnt1) =
+      betree_Node_apply_messages_back self.right params node_id_cnt msgs_right
+        st in
+    Return ({ self with right = n }, node_id_cnt1)
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages]: forward function
+    Source: 'src/betree.rs', lines 588:4-593:5 *)
+and betree_Node_apply_messages
+  (self : betree_Node_t) (params : betree_Params_t)
+  (node_id_cnt : betree_NodeIdCounter_t)
+  (msgs : betree_List_t (u64 & betree_Message_t)) (st : state) :
+  Tot (result (state & unit))
+  (decreases (
+    betree_Node_apply_messages_decreases self params node_id_cnt msgs st))
+  =
+  begin match self with
+  | Betree_Node_Internal node ->
+    let* (st1, content) = betree_load_internal_node node.id st in
+    let* content1 = betree_Node_apply_messages_to_internal content msgs in
+    let* num_msgs = betree_List_len (u64 & betree_Message_t) content1 in
+    if num_msgs >= params.min_flush_size
+    then
+      let* (st2, content2) =
+        betree_Internal_flush node params node_id_cnt content1 st1 in
+      let* (node1, _) =
+        betree_Internal_flush_back node params node_id_cnt content1 st1 in
+      let* (st3, _) = betree_store_internal_node node1.id content2 st2 in
+      Return (st3, ())
+    else
+      let* (st2, _) = betree_store_internal_node node.id content1 st1 in
+      Return (st2, ())
+  | Betree_Node_Leaf node ->
+    let* (st1, content) = betree_load_leaf_node node.id st in
+    let* content1 = betree_Node_apply_messages_to_leaf content msgs in
+    let* len = betree_List_len (u64 & u64) content1 in
+    let* i = u64_mul 2 params.split_size in
+    if len >= i
+    then
+      let* (st2, _) = betree_Leaf_split node content1 params node_id_cnt st1 in
+      let* (st3, _) = betree_store_leaf_node node.id Betree_List_Nil st2 in
+      Return (st3, ())
+    else
+      let* (st2, _) = betree_store_leaf_node node.id content1 st1 in
+      Return (st2, ())
+  end
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages]: backward function 0
+    Source: 'src/betree.rs', lines 588:4-593:5 *)
+and betree_Node_apply_messages_back
+  (self : betree_Node_t) (params : betree_Params_t)
+  (node_id_cnt : betree_NodeIdCounter_t)
+  (msgs : betree_List_t (u64 & betree_Message_t)) (st : state) :
+  Tot (result (betree_Node_t & betree_NodeIdCounter_t))
+  (decreases (
+    betree_Node_apply_messages_decreases self params node_id_cnt msgs st))
+  =
+  begin match self with
+  | Betree_Node_Internal node ->
+    let* (st1, content) = betree_load_internal_node node.id st in
+    let* content1 = betree_Node_apply_messages_to_internal content msgs in
+    let* num_msgs = betree_List_len (u64 & betree_Message_t) content1 in
+    if num_msgs >= params.min_flush_size
+    then
+      let* (st2, content2) =
+        betree_Internal_flush node params node_id_cnt content1 st1 in
+      let* (node1, node_id_cnt1) =
+        betree_Internal_flush_back node params node_id_cnt content1 st1 in
+      let* _ = betree_store_internal_node node1.id content2 st2 in
+      Return (Betree_Node_Internal node1, node_id_cnt1)
+    else
+      let* _ = betree_store_internal_node node.id content1 st1 in
+      Return (Betree_Node_Internal node, node_id_cnt)
+  | Betree_Node_Leaf node ->
+    let* (st1, content) = betree_load_leaf_node node.id st in
+    let* content1 = betree_Node_apply_messages_to_leaf content msgs in
+    let* len = betree_List_len (u64 & u64) content1 in
+    let* i = u64_mul 2 params.split_size in
+    if len >= i
+    then
+      let* (st2, new_node) =
+        betree_Leaf_split node content1 params node_id_cnt st1 in
+      let* _ = betree_store_leaf_node node.id Betree_List_Nil st2 in
+      let* node_id_cnt1 =
+        betree_Leaf_split_back node content1 params node_id_cnt st1 in
+      Return (Betree_Node_Internal new_node, node_id_cnt1)
+    else
+      let* _ = betree_store_leaf_node node.id content1 st1 in
+      Return (Betree_Node_Leaf { node with size = len }, node_id_cnt)
+  end
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply]: forward function
+    Source: 'src/betree.rs', lines 576:4-582:5 *)
+let betree_Node_apply
+  (self : betree_Node_t) (params : betree_Params_t)
+  (node_id_cnt : betree_NodeIdCounter_t) (key : u64)
+  (new_msg : betree_Message_t) (st : state) :
+  result (state & unit)
+  =
+  let l = Betree_List_Nil in
+  let* (st1, _) =
+    betree_Node_apply_messages self params node_id_cnt (Betree_List_Cons (key,
+      new_msg) l) st in
+  let* _ =
+    betree_Node_apply_messages_back self params node_id_cnt (Betree_List_Cons
+      (key, new_msg) l) st in
+  Return (st1, ())
+
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply]: backward function 0
+    Source: 'src/betree.rs', lines 576:4-582:5 *)
+let betree_Node_apply_back
+  (self : betree_Node_t) (params : betree_Params_t)
+  (node_id_cnt : betree_NodeIdCounter_t) (key : u64)
+  (new_msg : betree_Message_t) (st : state) :
+  result (betree_Node_t & betree_NodeIdCounter_t)
+  =
+  let l = Betree_List_Nil in
+  betree_Node_apply_messages_back self params node_id_cnt (Betree_List_Cons
+    (key, new_msg) l) st
+
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::new]: forward function
+    Source: 'src/betree.rs', lines 849:4-849:60 *)
+let betree_BeTree_new
+  (min_flush_size : u64) (split_size : u64) (st : state) :
+  result (state & betree_BeTree_t)
+  =
+  let* node_id_cnt = betree_NodeIdCounter_new in
+  let* id = betree_NodeIdCounter_fresh_id node_id_cnt in
+  let* (st1, _) = betree_store_leaf_node id Betree_List_Nil st in
+  let* node_id_cnt1 = betree_NodeIdCounter_fresh_id_back node_id_cnt in
+  Return (st1,
+    {
+      params = { min_flush_size = min_flush_size; split_size = split_size };
+      node_id_cnt = node_id_cnt1;
+      root = (Betree_Node_Leaf { id = id; size = 0 })
+    })
+
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::apply]: forward function
+    Source: 'src/betree.rs', lines 868:4-868:47 *)
+let betree_BeTree_apply
+  (self : betree_BeTree_t) (key : u64) (msg : betree_Message_t) (st : state) :
+  result (state & unit)
+  =
+  let* (st1, _) =
+    betree_Node_apply self.root self.params self.node_id_cnt key msg st in
+  let* _ =
+    betree_Node_apply_back self.root self.params self.node_id_cnt key msg st in
+  Return (st1, ())
+
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::apply]: backward function 0
+    Source: 'src/betree.rs', lines 868:4-868:47 *)
+let betree_BeTree_apply_back
+  (self : betree_BeTree_t) (key : u64) (msg : betree_Message_t) (st : state) :
+  result betree_BeTree_t
+  =
+  let* (n, nic) =
+    betree_Node_apply_back self.root self.params self.node_id_cnt key msg st in
+  Return { self with node_id_cnt = nic; root = n }
+
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::insert]: forward function
+    Source: 'src/betree.rs', lines 874:4-874:52 *)
+let betree_BeTree_insert
+  (self : betree_BeTree_t) (key : u64) (value : u64) (st : state) :
+  result (state & unit)
+  =
+  let* (st1, _) = betree_BeTree_apply self key (Betree_Message_Insert value) st
+    in
+  let* _ = betree_BeTree_apply_back self key (Betree_Message_Insert value) st
+    in
+  Return (st1, ())
+
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::insert]: backward function 0
+    Source: 'src/betree.rs', lines 874:4-874:52 *)
+let betree_BeTree_insert_back
+  (self : betree_BeTree_t) (key : u64) (value : u64) (st : state) :
+  result betree_BeTree_t
+  =
+  betree_BeTree_apply_back self key (Betree_Message_Insert value) st
+
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::delete]: forward function
+    Source: 'src/betree.rs', lines 880:4-880:38 *)
+let betree_BeTree_delete
+  (self : betree_BeTree_t) (key : u64) (st : state) : result (state & unit) =
+  let* (st1, _) = betree_BeTree_apply self key Betree_Message_Delete st in
+  let* _ = betree_BeTree_apply_back self key Betree_Message_Delete st in
+  Return (st1, ())
+
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::delete]: backward function 0
+    Source: 'src/betree.rs', lines 880:4-880:38 *)
+let betree_BeTree_delete_back
+  (self : betree_BeTree_t) (key : u64) (st : state) : result betree_BeTree_t =
+  betree_BeTree_apply_back self key Betree_Message_Delete st
+
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::upsert]: forward function
+    Source: 'src/betree.rs', lines 886:4-886:59 *)
+let betree_BeTree_upsert
+  (self : betree_BeTree_t) (key : u64) (upd : betree_UpsertFunState_t)
+  (st : state) :
+  result (state & unit)
+  =
+  let* (st1, _) = betree_BeTree_apply self key (Betree_Message_Upsert upd) st
+    in
+  let* _ = betree_BeTree_apply_back self key (Betree_Message_Upsert upd) st in
+  Return (st1, ())
+
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::upsert]: backward function 0
+    Source: 'src/betree.rs', lines 886:4-886:59 *)
+let betree_BeTree_upsert_back
+  (self : betree_BeTree_t) (key : u64) (upd : betree_UpsertFunState_t)
+  (st : state) :
+  result betree_BeTree_t
+  =
+  betree_BeTree_apply_back self key (Betree_Message_Upsert upd) st
+
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::lookup]: forward function
+    Source: 'src/betree.rs', lines 895:4-895:62 *)
+let betree_BeTree_lookup
+  (self : betree_BeTree_t) (key : u64) (st : state) :
+  result (state & (option u64))
+  =
+  betree_Node_lookup self.root key st
+
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::lookup]: backward function 0
+    Source: 'src/betree.rs', lines 895:4-895:62 *)
+let betree_BeTree_lookup_back
+  (self : betree_BeTree_t) (key : u64) (st : state) : result betree_BeTree_t =
+  let* n = betree_Node_lookup_back self.root key st in
+  Return { self with root = n }
+
+(** [betree_main::main]: forward function
+    Source: 'src/betree_main.rs', lines 5:0-5:9 *)
+let main : result unit =
+  Return ()
+
+(** Unit test for [betree_main::main] *)
+let _ = assert_norm (main = Return ())
+
diff --git a/tests/fstar-split/betree/BetreeMain.FunsExternal.fsti b/tests/fstar-split/betree/BetreeMain.FunsExternal.fsti
new file mode 100644
index 00000000..cd2f956f
--- /dev/null
+++ b/tests/fstar-split/betree/BetreeMain.FunsExternal.fsti
@@ -0,0 +1,35 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [betree_main]: external function declarations *)
+module BetreeMain.FunsExternal
+open Primitives
+include BetreeMain.Types
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [betree_main::betree_utils::load_internal_node]: forward function
+    Source: 'src/betree_utils.rs', lines 98:0-98:63 *)
+val betree_utils_load_internal_node
+  : u64 -> state -> result (state & (betree_List_t (u64 & betree_Message_t)))
+
+(** [betree_main::betree_utils::store_internal_node]: forward function
+    Source: 'src/betree_utils.rs', lines 115:0-115:71 *)
+val betree_utils_store_internal_node
+  :
+  u64 -> betree_List_t (u64 & betree_Message_t) -> state -> result (state &
+    unit)
+
+(** [betree_main::betree_utils::load_leaf_node]: forward function
+    Source: 'src/betree_utils.rs', lines 132:0-132:55 *)
+val betree_utils_load_leaf_node
+  : u64 -> state -> result (state & (betree_List_t (u64 & u64)))
+
+(** [betree_main::betree_utils::store_leaf_node]: forward function
+    Source: 'src/betree_utils.rs', lines 145:0-145:63 *)
+val betree_utils_store_leaf_node
+  : u64 -> betree_List_t (u64 & u64) -> state -> result (state & unit)
+
+(** [core::option::{core::option::Option<T>}::unwrap]: forward function
+    Source: '/rustc/d59363ad0b6391b7fc5bbb02c9ccf9300eef3753/library/core/src/option.rs', lines 932:4-932:34 *)
+val core_option_Option_unwrap
+  (t : Type0) : option t -> state -> result (state & t)
+
diff --git a/tests/fstar-split/betree/BetreeMain.Types.fst b/tests/fstar-split/betree/BetreeMain.Types.fst
new file mode 100644
index 00000000..b87219b2
--- /dev/null
+++ b/tests/fstar-split/betree/BetreeMain.Types.fst
@@ -0,0 +1,61 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [betree_main]: type definitions *)
+module BetreeMain.Types
+open Primitives
+include BetreeMain.TypesExternal
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [betree_main::betree::List]
+    Source: 'src/betree.rs', lines 17:0-17:23 *)
+type betree_List_t (t : Type0) =
+| Betree_List_Cons : t -> betree_List_t t -> betree_List_t t
+| Betree_List_Nil : betree_List_t t
+
+(** [betree_main::betree::UpsertFunState]
+    Source: 'src/betree.rs', lines 63:0-63:23 *)
+type betree_UpsertFunState_t =
+| Betree_UpsertFunState_Add : u64 -> betree_UpsertFunState_t
+| Betree_UpsertFunState_Sub : u64 -> betree_UpsertFunState_t
+
+(** [betree_main::betree::Message]
+    Source: 'src/betree.rs', lines 69:0-69:23 *)
+type betree_Message_t =
+| Betree_Message_Insert : u64 -> betree_Message_t
+| Betree_Message_Delete : betree_Message_t
+| Betree_Message_Upsert : betree_UpsertFunState_t -> betree_Message_t
+
+(** [betree_main::betree::Leaf]
+    Source: 'src/betree.rs', lines 167:0-167:11 *)
+type betree_Leaf_t = { id : u64; size : u64; }
+
+(** [betree_main::betree::Internal]
+    Source: 'src/betree.rs', lines 156:0-156:15 *)
+type betree_Internal_t =
+{
+  id : u64; pivot : u64; left : betree_Node_t; right : betree_Node_t;
+}
+
+(** [betree_main::betree::Node]
+    Source: 'src/betree.rs', lines 179:0-179:9 *)
+and betree_Node_t =
+| Betree_Node_Internal : betree_Internal_t -> betree_Node_t
+| Betree_Node_Leaf : betree_Leaf_t -> betree_Node_t
+
+(** [betree_main::betree::Params]
+    Source: 'src/betree.rs', lines 187:0-187:13 *)
+type betree_Params_t = { min_flush_size : u64; split_size : u64; }
+
+(** [betree_main::betree::NodeIdCounter]
+    Source: 'src/betree.rs', lines 201:0-201:20 *)
+type betree_NodeIdCounter_t = { next_node_id : u64; }
+
+(** [betree_main::betree::BeTree]
+    Source: 'src/betree.rs', lines 218:0-218:17 *)
+type betree_BeTree_t =
+{
+  params : betree_Params_t;
+  node_id_cnt : betree_NodeIdCounter_t;
+  root : betree_Node_t;
+}
+
diff --git a/tests/fstar-split/betree/BetreeMain.TypesExternal.fsti b/tests/fstar-split/betree/BetreeMain.TypesExternal.fsti
new file mode 100644
index 00000000..1b2c53a6
--- /dev/null
+++ b/tests/fstar-split/betree/BetreeMain.TypesExternal.fsti
@@ -0,0 +1,10 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [betree_main]: external type declarations *)
+module BetreeMain.TypesExternal
+open Primitives
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** The state type used in the state-error monad *)
+val state : Type0
+
diff --git a/tests/fstar-split/betree/Makefile b/tests/fstar-split/betree/Makefile
new file mode 100644
index 00000000..fa7d1f36
--- /dev/null
+++ b/tests/fstar-split/betree/Makefile
@@ -0,0 +1,49 @@
+# This file was automatically generated - modify ../Makefile.template instead
+INCLUDE_DIRS = .
+
+FSTAR_INCLUDES = $(addprefix --include ,$(INCLUDE_DIRS))
+
+FSTAR_HINTS ?= --use_hints --use_hint_hashes --record_hints
+
+FSTAR_OPTIONS = $(FSTAR_HINTS) \
+  --cache_checked_modules $(FSTAR_INCLUDES) --cmi \
+  --warn_error '+241@247+285-274' \
+
+FSTAR_EXE ?= fstar.exe
+FSTAR_NO_FLAGS = $(FSTAR_EXE) --already_cached 'Prims FStar LowStar Steel' --odir obj --cache_dir obj
+
+FSTAR = $(FSTAR_NO_FLAGS) $(FSTAR_OPTIONS)
+
+# The F* roots are used to compute the dependency graph, and generate the .depend file
+FSTAR_ROOTS ?= $(wildcard *.fst *.fsti)
+
+# Build all the files
+all: $(addprefix obj/,$(addsuffix .checked,$(FSTAR_ROOTS)))
+
+# This is the right way to ensure the .depend file always gets re-built.
+ifeq (,$(filter %-in,$(MAKECMDGOALS)))
+ifndef NODEPEND
+ifndef MAKE_RESTARTS
+.depend: .FORCE
+	$(FSTAR_NO_FLAGS) --dep full $(notdir $(FSTAR_ROOTS)) > $@
+
+.PHONY: .FORCE
+.FORCE:
+endif
+endif
+
+include .depend
+endif
+
+# For the interactive mode
+%.fst-in %.fsti-in:
+	@echo $(FSTAR_OPTIONS)
+
+# Generete the .checked files in batch mode
+%.checked:
+	$(FSTAR) $(FSTAR_OPTIONS) $< && \
+	touch -c $@
+
+.PHONY: clean
+clean:
+	rm -f obj/*
diff --git a/tests/fstar-split/betree/Primitives.fst b/tests/fstar-split/betree/Primitives.fst
new file mode 100644
index 00000000..a3ffbde4
--- /dev/null
+++ b/tests/fstar-split/betree/Primitives.fst
@@ -0,0 +1,884 @@
+/// This file lists primitive and assumed functions and types
+module Primitives
+open FStar.Mul
+open FStar.List.Tot
+
+#set-options "--z3rlimit 15 --fuel 0 --ifuel 1"
+
+(*** Utilities *)
+val list_update (#a : Type0) (ls : list a) (i : nat{i < length ls}) (x : a) :
+  ls':list a{
+    length ls' = length ls /\
+    index ls' i == x
+  }
+#push-options "--fuel 1"
+let rec list_update #a ls i x =
+  match ls with
+  | x' :: ls -> if i = 0 then x :: ls else x' :: list_update ls (i-1) x
+#pop-options
+
+(*** Result *)
+type error : Type0 =
+| Failure
+| OutOfFuel
+
+type result (a : Type0) : Type0 =
+| Return : v:a -> result a
+| Fail : e:error -> result a
+
+// Monadic return operator
+unfold let return (#a : Type0) (x : a) : result a = Return x
+
+// Monadic bind operator.
+// Allows to use the notation:
+// ```
+// let* x = y in
+// ...
+// ```
+unfold let (let*) (#a #b : Type0) (m: result a)
+  (f: (x:a) -> Pure (result b) (requires (m == Return x)) (ensures fun _ -> True)) :
+  result b =
+  match m with
+  | Return x -> f x
+  | Fail e   -> Fail e
+
+// Monadic assert(...)
+let massert (b:bool) : result unit = if b then Return () else Fail Failure
+
+// Normalize and unwrap a successful result (used for globals).
+let eval_global (#a : Type0) (x : result a{Return? (normalize_term x)}) : a = Return?.v x
+
+(*** Misc *)
+type char = FStar.Char.char
+type string = string
+
+let is_zero (n: nat) : bool = n = 0
+let decrease (n: nat{n > 0}) : nat = n - 1
+
+let core_mem_replace (a : Type0) (x : a) (y : a) : a = x
+let core_mem_replace_back (a : Type0) (x : a) (y : a) : a = y
+
+// We don't really use raw pointers for now
+type mut_raw_ptr (t : Type0) = { v : t }
+type const_raw_ptr (t : Type0) = { v : t }
+
+(*** Scalars *)
+/// Rem.: most of the following code was partially generated
+
+assume val size_numbits : pos
+
+// TODO: we could use FStar.Int.int_t and FStar.UInt.int_t
+
+let isize_min : int = -9223372036854775808 // TODO: should be opaque
+let isize_max : int = 9223372036854775807 // TODO: should be opaque
+let i8_min : int = -128
+let i8_max : int = 127
+let i16_min : int = -32768
+let i16_max : int = 32767
+let i32_min : int = -2147483648
+let i32_max : int = 2147483647
+let i64_min : int = -9223372036854775808
+let i64_max : int = 9223372036854775807
+let i128_min : int = -170141183460469231731687303715884105728
+let i128_max : int = 170141183460469231731687303715884105727
+let usize_min : int = 0
+let usize_max : int = 4294967295 // TODO: should be opaque
+let u8_min : int = 0
+let u8_max : int = 255
+let u16_min : int = 0
+let u16_max : int = 65535
+let u32_min : int = 0
+let u32_max : int = 4294967295
+let u64_min : int = 0
+let u64_max : int = 18446744073709551615
+let u128_min : int = 0
+let u128_max : int = 340282366920938463463374607431768211455
+
+type scalar_ty =
+| Isize
+| I8
+| I16
+| I32
+| I64
+| I128
+| Usize
+| U8
+| U16
+| U32
+| U64
+| U128
+
+let is_unsigned = function
+  | Isize | I8 | I16 | I32 | I64 | I128 -> false
+  | Usize | U8 | U16 | U32 | U64 | U128 -> true
+
+let scalar_min (ty : scalar_ty) : int =
+  match ty with
+  | Isize -> isize_min
+  | I8 -> i8_min
+  | I16 -> i16_min
+  | I32 -> i32_min
+  | I64 -> i64_min
+  | I128 -> i128_min
+  | Usize -> usize_min
+  | U8 -> u8_min
+  | U16 -> u16_min
+  | U32 -> u32_min
+  | U64 -> u64_min
+  | U128 -> u128_min
+
+let scalar_max (ty : scalar_ty) : int =
+  match ty with
+  | Isize -> isize_max
+  | I8 -> i8_max
+  | I16 -> i16_max
+  | I32 -> i32_max
+  | I64 -> i64_max
+  | I128 -> i128_max
+  | Usize -> usize_max
+  | U8 -> u8_max
+  | U16 -> u16_max
+  | U32 -> u32_max
+  | U64 -> u64_max
+  | U128 -> u128_max
+
+type scalar (ty : scalar_ty) : eqtype = x:int{scalar_min ty <= x && x <= scalar_max ty}
+
+let mk_scalar (ty : scalar_ty) (x : int) : result (scalar ty) =
+  if scalar_min ty <= x && scalar_max ty >= x then Return x else Fail Failure
+
+let scalar_neg (#ty : scalar_ty) (x : scalar ty) : result (scalar ty) = mk_scalar ty (-x)
+
+let scalar_div (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  if y <> 0 then mk_scalar ty (x / y) else Fail Failure
+
+/// The remainder operation
+let int_rem (x : int) (y : int{y <> 0}) : int =
+  if x >= 0 then (x % y) else -(x % y)
+
+(* Checking consistency with Rust *)
+let _ = assert_norm(int_rem 1 2 = 1)
+let _ = assert_norm(int_rem (-1) 2 = -1)
+let _ = assert_norm(int_rem 1 (-2) = 1)
+let _ = assert_norm(int_rem (-1) (-2) = -1)
+
+let scalar_rem (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  if y <> 0 then mk_scalar ty (int_rem x y) else Fail Failure
+
+let scalar_add (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  mk_scalar ty (x + y)
+
+let scalar_sub (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  mk_scalar ty (x - y)
+
+let scalar_mul (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  mk_scalar ty (x * y)
+
+let scalar_xor (#ty : scalar_ty)
+    (x : scalar ty) (y : scalar ty) : scalar ty =
+  match ty with
+  | U8 -> FStar.UInt.logxor #8 x y
+  | U16 -> FStar.UInt.logxor #16 x y
+  | U32 -> FStar.UInt.logxor #32 x y
+  | U64 -> FStar.UInt.logxor #64 x y
+  | U128 -> FStar.UInt.logxor #128 x y
+  | Usize -> admit() // TODO
+  | I8 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 8);
+    normalize_spec (scalar I8);
+    FStar.Int.logxor #8 x y
+  | I16 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 16);
+    normalize_spec (scalar I16);
+    FStar.Int.logxor #16 x y
+  | I32 -> FStar.Int.logxor #32 x y
+  | I64 -> FStar.Int.logxor #64 x y
+  | I128 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 128);
+    normalize_spec (scalar I128);
+    FStar.Int.logxor #128 x y
+  | Isize -> admit() // TODO
+
+let scalar_or (#ty : scalar_ty)
+    (x : scalar ty) (y : scalar ty) : scalar ty =
+  match ty with
+  | U8 -> FStar.UInt.logor #8 x y
+  | U16 -> FStar.UInt.logor #16 x y
+  | U32 -> FStar.UInt.logor #32 x y
+  | U64 -> FStar.UInt.logor #64 x y
+  | U128 -> FStar.UInt.logor #128 x y
+  | Usize -> admit() // TODO
+  | I8 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 8);
+    normalize_spec (scalar I8);
+    FStar.Int.logor #8 x y
+  | I16 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 16);
+    normalize_spec (scalar I16);
+    FStar.Int.logor #16 x y
+  | I32 -> FStar.Int.logor #32 x y
+  | I64 -> FStar.Int.logor #64 x y
+  | I128 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 128);
+    normalize_spec (scalar I128);
+    FStar.Int.logor #128 x y
+  | Isize -> admit() // TODO
+
+let scalar_and (#ty : scalar_ty)
+    (x : scalar ty) (y : scalar ty) : scalar ty =
+  match ty with
+  | U8 -> FStar.UInt.logand #8 x y
+  | U16 -> FStar.UInt.logand #16 x y
+  | U32 -> FStar.UInt.logand #32 x y
+  | U64 -> FStar.UInt.logand #64 x y
+  | U128 -> FStar.UInt.logand #128 x y
+  | Usize -> admit() // TODO
+  | I8 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 8);
+    normalize_spec (scalar I8);
+    FStar.Int.logand #8 x y
+  | I16 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 16);
+    normalize_spec (scalar I16);
+    FStar.Int.logand #16 x y
+  | I32 -> FStar.Int.logand #32 x y
+  | I64 -> FStar.Int.logand #64 x y
+  | I128 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 128);
+    normalize_spec (scalar I128);
+    FStar.Int.logand #128 x y
+  | Isize -> admit() // TODO
+
+// Shift left
+let scalar_shl (#ty0 #ty1 : scalar_ty)
+    (x : scalar ty0) (y : scalar ty1) : result (scalar ty0) =
+  admit()
+
+// Shift right
+let scalar_shr (#ty0 #ty1 : scalar_ty)
+    (x : scalar ty0) (y : scalar ty1) : result (scalar ty0) =
+  admit()
+
+(** Cast an integer from a [src_ty] to a [tgt_ty] *)
+// TODO: check the semantics of casts in Rust
+let scalar_cast (src_ty : scalar_ty) (tgt_ty : scalar_ty) (x : scalar src_ty) : result (scalar tgt_ty) =
+  mk_scalar tgt_ty x
+
+// This can't fail, but for now we make all casts faillible (easier for the translation)
+let scalar_cast_bool (tgt_ty : scalar_ty) (x : bool) : result (scalar tgt_ty) =
+  mk_scalar tgt_ty (if x then 1 else 0)
+
+/// The scalar types
+type isize : eqtype = scalar Isize
+type i8    : eqtype = scalar I8
+type i16   : eqtype = scalar I16
+type i32   : eqtype = scalar I32
+type i64   : eqtype = scalar I64
+type i128  : eqtype = scalar I128
+type usize : eqtype = scalar Usize
+type u8    : eqtype = scalar U8
+type u16   : eqtype = scalar U16
+type u32   : eqtype = scalar U32
+type u64   : eqtype = scalar U64
+type u128  : eqtype = scalar U128
+
+
+let core_isize_min : isize = isize_min
+let core_isize_max : isize = isize_max
+let core_i8_min    : i8 = i8_min
+let core_i8_max    : i8 = i8_max
+let core_i16_min   : i16 = i16_min
+let core_i16_max   : i16 = i16_max
+let core_i32_min   : i32 = i32_min
+let core_i32_max   : i32 = i32_max
+let core_i64_min   : i64 = i64_min
+let core_i64_max   : i64 = i64_max
+let core_i128_min  : i128 = i128_min
+let core_i128_max  : i128 = i128_max
+
+let core_usize_min : usize = usize_min
+let core_usize_max : usize = usize_max
+let core_u8_min    : u8 = u8_min
+let core_u8_max    : u8 = u8_max
+let core_u16_min   : u16 = u16_min
+let core_u16_max   : u16 = u16_max
+let core_u32_min   : u32 = u32_min
+let core_u32_max   : u32 = u32_max
+let core_u64_min   : u64 = u64_min
+let core_u64_max   : u64 = u64_max
+let core_u128_min  : u128 = u128_min
+let core_u128_max  : u128 = u128_max
+
+/// Negation
+let isize_neg = scalar_neg #Isize
+let i8_neg = scalar_neg #I8
+let i16_neg = scalar_neg #I16
+let i32_neg = scalar_neg #I32
+let i64_neg = scalar_neg #I64
+let i128_neg = scalar_neg #I128
+
+/// Division
+let isize_div = scalar_div #Isize
+let i8_div = scalar_div #I8
+let i16_div = scalar_div #I16
+let i32_div = scalar_div #I32
+let i64_div = scalar_div #I64
+let i128_div = scalar_div #I128
+let usize_div = scalar_div #Usize
+let u8_div = scalar_div #U8
+let u16_div = scalar_div #U16
+let u32_div = scalar_div #U32
+let u64_div = scalar_div #U64
+let u128_div = scalar_div #U128
+
+/// Remainder
+let isize_rem = scalar_rem #Isize
+let i8_rem = scalar_rem #I8
+let i16_rem = scalar_rem #I16
+let i32_rem = scalar_rem #I32
+let i64_rem = scalar_rem #I64
+let i128_rem = scalar_rem #I128
+let usize_rem = scalar_rem #Usize
+let u8_rem = scalar_rem #U8
+let u16_rem = scalar_rem #U16
+let u32_rem = scalar_rem #U32
+let u64_rem = scalar_rem #U64
+let u128_rem = scalar_rem #U128
+
+/// Addition
+let isize_add = scalar_add #Isize
+let i8_add = scalar_add #I8
+let i16_add = scalar_add #I16
+let i32_add = scalar_add #I32
+let i64_add = scalar_add #I64
+let i128_add = scalar_add #I128
+let usize_add = scalar_add #Usize
+let u8_add = scalar_add #U8
+let u16_add = scalar_add #U16
+let u32_add = scalar_add #U32
+let u64_add = scalar_add #U64
+let u128_add = scalar_add #U128
+
+/// Subtraction
+let isize_sub = scalar_sub #Isize
+let i8_sub = scalar_sub #I8
+let i16_sub = scalar_sub #I16
+let i32_sub = scalar_sub #I32
+let i64_sub = scalar_sub #I64
+let i128_sub = scalar_sub #I128
+let usize_sub = scalar_sub #Usize
+let u8_sub = scalar_sub #U8
+let u16_sub = scalar_sub #U16
+let u32_sub = scalar_sub #U32
+let u64_sub = scalar_sub #U64
+let u128_sub = scalar_sub #U128
+
+/// Multiplication
+let isize_mul = scalar_mul #Isize
+let i8_mul = scalar_mul #I8
+let i16_mul = scalar_mul #I16
+let i32_mul = scalar_mul #I32
+let i64_mul = scalar_mul #I64
+let i128_mul = scalar_mul #I128
+let usize_mul = scalar_mul #Usize
+let u8_mul = scalar_mul #U8
+let u16_mul = scalar_mul #U16
+let u32_mul = scalar_mul #U32
+let u64_mul = scalar_mul #U64
+let u128_mul = scalar_mul #U128
+
+/// Xor
+let u8_xor = scalar_xor #U8
+let u16_xor = scalar_xor #U16
+let u32_xor = scalar_xor #U32
+let u64_xor = scalar_xor #U64
+let u128_xor = scalar_xor #U128
+let usize_xor = scalar_xor #Usize
+let i8_xor = scalar_xor #I8
+let i16_xor = scalar_xor #I16
+let i32_xor = scalar_xor #I32
+let i64_xor = scalar_xor #I64
+let i128_xor = scalar_xor #I128
+let isize_xor = scalar_xor #Isize
+
+/// Or
+let u8_or = scalar_or #U8
+let u16_or = scalar_or #U16
+let u32_or = scalar_or #U32
+let u64_or = scalar_or #U64
+let u128_or = scalar_or #U128
+let usize_or = scalar_or #Usize
+let i8_or = scalar_or #I8
+let i16_or = scalar_or #I16
+let i32_or = scalar_or #I32
+let i64_or = scalar_or #I64
+let i128_or = scalar_or #I128
+let isize_or = scalar_or #Isize
+
+/// And
+let u8_and = scalar_and #U8
+let u16_and = scalar_and #U16
+let u32_and = scalar_and #U32
+let u64_and = scalar_and #U64
+let u128_and = scalar_and #U128
+let usize_and = scalar_and #Usize
+let i8_and = scalar_and #I8
+let i16_and = scalar_and #I16
+let i32_and = scalar_and #I32
+let i64_and = scalar_and #I64
+let i128_and = scalar_and #I128
+let isize_and = scalar_and #Isize
+
+/// Shift left
+let u8_shl #ty = scalar_shl #U8 #ty
+let u16_shl #ty = scalar_shl #U16 #ty
+let u32_shl #ty = scalar_shl #U32 #ty
+let u64_shl #ty = scalar_shl #U64 #ty
+let u128_shl #ty = scalar_shl #U128 #ty
+let usize_shl #ty = scalar_shl #Usize #ty
+let i8_shl #ty = scalar_shl #I8 #ty
+let i16_shl #ty = scalar_shl #I16 #ty
+let i32_shl #ty = scalar_shl #I32 #ty
+let i64_shl #ty = scalar_shl #I64 #ty
+let i128_shl #ty = scalar_shl #I128 #ty
+let isize_shl #ty = scalar_shl #Isize #ty
+
+/// Shift right
+let u8_shr #ty = scalar_shr #U8 #ty
+let u16_shr #ty = scalar_shr #U16 #ty
+let u32_shr #ty = scalar_shr #U32 #ty
+let u64_shr #ty = scalar_shr #U64 #ty
+let u128_shr #ty = scalar_shr #U128 #ty
+let usize_shr #ty = scalar_shr #Usize #ty
+let i8_shr #ty = scalar_shr #I8 #ty
+let i16_shr #ty = scalar_shr #I16 #ty
+let i32_shr #ty = scalar_shr #I32 #ty
+let i64_shr #ty = scalar_shr #I64 #ty
+let i128_shr #ty = scalar_shr #I128 #ty
+let isize_shr #ty = scalar_shr #Isize #ty
+
+(*** core::ops *)
+
+// Trait declaration: [core::ops::index::Index]
+noeq type core_ops_index_Index (self idx : Type0) = {
+  output : Type0;
+  index : self → idx → result output
+}
+
+// Trait declaration: [core::ops::index::IndexMut]
+noeq type core_ops_index_IndexMut (self idx : Type0) = {
+  indexInst : core_ops_index_Index self idx;
+  index_mut : self → idx → result indexInst.output;
+  index_mut_back : self → idx → indexInst.output → result self;
+}
+
+// Trait declaration [core::ops::deref::Deref]
+noeq type core_ops_deref_Deref (self : Type0) = {
+  target : Type0;
+  deref : self → result target;
+}
+
+// Trait declaration [core::ops::deref::DerefMut]
+noeq type core_ops_deref_DerefMut (self : Type0) = {
+  derefInst : core_ops_deref_Deref self;
+  deref_mut : self → result derefInst.target;
+  deref_mut_back : self → derefInst.target → result self;
+}
+
+type core_ops_range_Range (a : Type0) = {
+  start : a;
+  end_ : a;
+}
+
+(*** [alloc] *)
+
+let alloc_boxed_Box_deref (t : Type0) (x : t) : result t = Return x
+let alloc_boxed_Box_deref_mut (t : Type0) (x : t) : result t = Return x
+let alloc_boxed_Box_deref_mut_back (t : Type) (_ : t) (x : t) : result t = Return x
+
+// Trait instance
+let alloc_boxed_Box_coreopsDerefInst (self : Type0) : core_ops_deref_Deref self = {
+  target = self;
+  deref = alloc_boxed_Box_deref self;
+}
+
+// Trait instance
+let alloc_boxed_Box_coreopsDerefMutInst (self : Type0) : core_ops_deref_DerefMut self = {
+  derefInst = alloc_boxed_Box_coreopsDerefInst self;
+  deref_mut = alloc_boxed_Box_deref_mut self;
+  deref_mut_back = alloc_boxed_Box_deref_mut_back self;
+}
+
+(*** Array *)
+type array (a : Type0) (n : usize) = s:list a{length s = n}
+
+// We tried putting the normalize_term condition as a refinement on the list
+// but it didn't work. It works with the requires clause.
+let mk_array (a : Type0) (n : usize)
+  (l : list a) :
+  Pure (array a n)
+  (requires (normalize_term(FStar.List.Tot.length l) = n))
+  (ensures (fun _ -> True)) =
+  normalize_term_spec (FStar.List.Tot.length l);
+  l
+
+let array_index_usize (a : Type0) (n : usize) (x : array a n) (i : usize) : result a =
+  if i < length x then Return (index x i)
+  else Fail Failure
+
+let array_update_usize (a : Type0) (n : usize) (x : array a n) (i : usize) (nx : a) : result (array a n) =
+  if i < length x then Return (list_update x i nx)
+  else Fail Failure
+
+(*** Slice *)
+type slice (a : Type0) = s:list a{length s <= usize_max}
+
+let slice_len (a : Type0) (s : slice a) : usize = length s
+
+let slice_index_usize (a : Type0) (x : slice a) (i : usize) : result a =
+  if i < length x then Return (index x i)
+  else Fail Failure
+
+let slice_update_usize (a : Type0) (x : slice a) (i : usize) (nx : a) : result (slice a) =
+  if i < length x then Return (list_update x i nx)
+  else Fail Failure
+
+(*** Subslices *)
+
+let array_to_slice (a : Type0) (n : usize) (x : array a n) : result (slice a) = Return x
+let array_from_slice (a : Type0) (n : usize) (x : array a n) (s : slice a) : result (array a n) =
+  if length s = n then Return s
+  else Fail Failure
+
+// TODO: finish the definitions below (there lacks [List.drop] and [List.take] in the standard library *)
+let array_subslice (a : Type0) (n : usize) (x : array a n) (r : core_ops_range_Range usize) : result (slice a) =
+  admit()
+
+let array_update_subslice (a : Type0) (n : usize) (x : array a n) (r : core_ops_range_Range usize) (ns : slice a) : result (array a n) =
+  admit()
+
+let array_repeat (a : Type0) (n : usize) (x : a) : array a n =
+  admit()
+
+let slice_subslice (a : Type0) (x : slice a) (r : core_ops_range_Range usize) : result (slice a) =
+  admit()
+
+let slice_update_subslice (a : Type0) (x : slice a) (r : core_ops_range_Range usize) (ns : slice a) : result (slice a) =
+  admit()
+
+(*** Vector *)
+type alloc_vec_Vec (a : Type0) = v:list a{length v <= usize_max}
+
+let alloc_vec_Vec_new (a  : Type0) : alloc_vec_Vec a = assert_norm(length #a [] == 0); []
+let alloc_vec_Vec_len (a : Type0) (v : alloc_vec_Vec a) : usize = length v
+
+// Helper
+let alloc_vec_Vec_index_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) : result a =
+  if i < length v then Return (index v i) else Fail Failure
+// Helper
+let alloc_vec_Vec_update_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
+  if i < length v then Return (list_update v i x) else Fail Failure
+
+// The **forward** function shouldn't be used
+let alloc_vec_Vec_push_fwd (a  : Type0) (v : alloc_vec_Vec a) (x : a) : unit = ()
+let alloc_vec_Vec_push (a  : Type0) (v : alloc_vec_Vec a) (x : a) :
+  Pure (result (alloc_vec_Vec a))
+  (requires True)
+  (ensures (fun res ->
+    match res with
+    | Fail e -> e == Failure
+    | Return v' -> length v' = length v + 1)) =
+  if length v < usize_max then begin
+    (**) assert_norm(length [x] == 1);
+    (**) append_length v [x];
+    (**) assert(length (append v [x]) = length v + 1);
+    Return (append v [x])
+    end
+  else Fail Failure
+
+// The **forward** function shouldn't be used
+let alloc_vec_Vec_insert_fwd (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result unit =
+  if i < length v then Return () else Fail Failure
+let alloc_vec_Vec_insert (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
+  if i < length v then Return (list_update v i x) else Fail Failure
+
+// Trait declaration: [core::slice::index::private_slice_index::Sealed]
+type core_slice_index_private_slice_index_Sealed (self : Type0) = unit
+
+// Trait declaration: [core::slice::index::SliceIndex]
+noeq type core_slice_index_SliceIndex (self t : Type0) = {
+  sealedInst : core_slice_index_private_slice_index_Sealed self;
+  output : Type0;
+  get : self → t → result (option output);
+  get_mut : self → t → result (option output);
+  get_mut_back : self → t → option output → result t;
+  get_unchecked : self → const_raw_ptr t → result (const_raw_ptr output);
+  get_unchecked_mut : self → mut_raw_ptr t → result (mut_raw_ptr output);
+  index : self → t → result output;
+  index_mut : self → t → result output;
+  index_mut_back : self → t → output → result t;
+}
+
+// [core::slice::index::[T]::index]: forward function
+let core_slice_index_Slice_index
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (s : slice t) (i : idx) : result inst.output =
+  let* x = inst.get i s in
+  match x with
+  | None -> Fail Failure
+  | Some x -> Return x
+
+// [core::slice::index::Range:::get]: forward function
+let core_slice_index_RangeUsize_get (t : Type0) (i : core_ops_range_Range usize) (s : slice t) :
+  result (option (slice t)) =
+  admit () // TODO
+
+// [core::slice::index::Range::get_mut]: forward function
+let core_slice_index_RangeUsize_get_mut
+  (t : Type0) : core_ops_range_Range usize → slice t → result (option (slice t)) =
+  admit () // TODO
+
+// [core::slice::index::Range::get_mut]: backward function 0
+let core_slice_index_RangeUsize_get_mut_back
+  (t : Type0) :
+  core_ops_range_Range usize → slice t → option (slice t) → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::Range::get_unchecked]: forward function
+let core_slice_index_RangeUsize_get_unchecked
+  (t : Type0) :
+  core_ops_range_Range usize → const_raw_ptr (slice t) → result (const_raw_ptr (slice t)) =
+  // Don't know what the model should be - for now we always fail to make
+  // sure code which uses it fails
+  fun _ _ -> Fail Failure
+
+// [core::slice::index::Range::get_unchecked_mut]: forward function
+let core_slice_index_RangeUsize_get_unchecked_mut
+  (t : Type0) :
+  core_ops_range_Range usize → mut_raw_ptr (slice t) → result (mut_raw_ptr (slice t)) =
+  // Don't know what the model should be - for now we always fail to make
+  // sure code which uses it fails
+  fun _ _ -> Fail Failure
+
+// [core::slice::index::Range::index]: forward function
+let core_slice_index_RangeUsize_index
+  (t : Type0) : core_ops_range_Range usize → slice t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::Range::index_mut]: forward function
+let core_slice_index_RangeUsize_index_mut
+  (t : Type0) : core_ops_range_Range usize → slice t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::Range::index_mut]: backward function 0
+let core_slice_index_RangeUsize_index_mut_back
+  (t : Type0) : core_ops_range_Range usize → slice t → slice t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::[T]::index_mut]: forward function
+let core_slice_index_Slice_index_mut
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
+  slice t → idx → result inst.output =
+  admit () // 
+
+// [core::slice::index::[T]::index_mut]: backward function 0
+let core_slice_index_Slice_index_mut_back
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
+  slice t → idx → inst.output → result (slice t) =
+  admit () // TODO
+
+// [core::array::[T; N]::index]: forward function
+let core_array_Array_index
+  (t idx : Type0) (n : usize) (inst : core_ops_index_Index (slice t) idx)
+  (a : array t n) (i : idx) : result inst.output =
+  admit () // TODO
+
+// [core::array::[T; N]::index_mut]: forward function
+let core_array_Array_index_mut
+  (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
+  (a : array t n) (i : idx) : result inst.indexInst.output =
+  admit () // TODO
+
+// [core::array::[T; N]::index_mut]: backward function 0
+let core_array_Array_index_mut_back
+  (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
+  (a : array t n) (i : idx) (x : inst.indexInst.output) : result (array t n) =
+  admit () // TODO
+
+// Trait implementation: [core::slice::index::private_slice_index::Range]
+let core_slice_index_private_slice_index_SealedRangeUsizeInst
+  : core_slice_index_private_slice_index_Sealed (core_ops_range_Range usize) = ()
+
+// Trait implementation: [core::slice::index::Range]
+let core_slice_index_SliceIndexRangeUsizeSliceTInst (t : Type0) :
+  core_slice_index_SliceIndex (core_ops_range_Range usize) (slice t) = {
+  sealedInst = core_slice_index_private_slice_index_SealedRangeUsizeInst;
+  output = slice t;
+  get = core_slice_index_RangeUsize_get t;
+  get_mut = core_slice_index_RangeUsize_get_mut t;
+  get_mut_back = core_slice_index_RangeUsize_get_mut_back t;
+  get_unchecked = core_slice_index_RangeUsize_get_unchecked t;
+  get_unchecked_mut = core_slice_index_RangeUsize_get_unchecked_mut t;
+  index = core_slice_index_RangeUsize_index t;
+  index_mut = core_slice_index_RangeUsize_index_mut t;
+  index_mut_back = core_slice_index_RangeUsize_index_mut_back t;
+}
+
+// Trait implementation: [core::slice::index::[T]]
+let core_ops_index_IndexSliceTIInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_Index (slice t) idx = {
+  output = inst.output;
+  index = core_slice_index_Slice_index t idx inst;
+}
+
+// Trait implementation: [core::slice::index::[T]]
+let core_ops_index_IndexMutSliceTIInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_IndexMut (slice t) idx = {
+  indexInst = core_ops_index_IndexSliceTIInst t idx inst;
+  index_mut = core_slice_index_Slice_index_mut t idx inst;
+  index_mut_back = core_slice_index_Slice_index_mut_back t idx inst;
+}
+
+// Trait implementation: [core::array::[T; N]]
+let core_ops_index_IndexArrayInst (t idx : Type0) (n : usize)
+  (inst : core_ops_index_Index (slice t) idx) :
+  core_ops_index_Index (array t n) idx = {
+  output = inst.output;
+  index = core_array_Array_index t idx n inst;
+}
+
+// Trait implementation: [core::array::[T; N]]
+let core_ops_index_IndexMutArrayIInst (t idx : Type0) (n : usize)
+  (inst : core_ops_index_IndexMut (slice t) idx) :
+  core_ops_index_IndexMut (array t n) idx = {
+  indexInst = core_ops_index_IndexArrayInst t idx n inst.indexInst;
+  index_mut = core_array_Array_index_mut t idx n inst;
+  index_mut_back = core_array_Array_index_mut_back t idx n inst;
+}
+
+// [core::slice::index::usize::get]: forward function
+let core_slice_index_usize_get
+  (t : Type0) : usize → slice t → result (option t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_mut]: forward function
+let core_slice_index_usize_get_mut
+  (t : Type0) : usize → slice t → result (option t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_mut]: backward function 0
+let core_slice_index_usize_get_mut_back
+  (t : Type0) : usize → slice t → option t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_unchecked]: forward function
+let core_slice_index_usize_get_unchecked
+  (t : Type0) : usize → const_raw_ptr (slice t) → result (const_raw_ptr t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_unchecked_mut]: forward function
+let core_slice_index_usize_get_unchecked_mut
+  (t : Type0) : usize → mut_raw_ptr (slice t) → result (mut_raw_ptr t) =
+  admit () // TODO
+
+// [core::slice::index::usize::index]: forward function
+let core_slice_index_usize_index (t : Type0) : usize → slice t → result t =
+  admit () // TODO
+
+// [core::slice::index::usize::index_mut]: forward function
+let core_slice_index_usize_index_mut (t : Type0) : usize → slice t → result t =
+  admit () // TODO
+
+// [core::slice::index::usize::index_mut]: backward function 0
+let core_slice_index_usize_index_mut_back
+  (t : Type0) : usize → slice t → t → result (slice t) =
+  admit () // TODO
+
+// Trait implementation: [core::slice::index::private_slice_index::usize]
+let core_slice_index_private_slice_index_SealedUsizeInst
+  : core_slice_index_private_slice_index_Sealed usize = ()
+
+// Trait implementation: [core::slice::index::usize]
+let core_slice_index_SliceIndexUsizeSliceTInst (t : Type0) :
+  core_slice_index_SliceIndex usize (slice t) = {
+  sealedInst = core_slice_index_private_slice_index_SealedUsizeInst;
+  output = t;
+  get = core_slice_index_usize_get t;
+  get_mut = core_slice_index_usize_get_mut t;
+  get_mut_back = core_slice_index_usize_get_mut_back t;
+  get_unchecked = core_slice_index_usize_get_unchecked t;
+  get_unchecked_mut = core_slice_index_usize_get_unchecked_mut t;
+  index = core_slice_index_usize_index t;
+  index_mut = core_slice_index_usize_index_mut t;
+  index_mut_back = core_slice_index_usize_index_mut_back t;
+}
+
+// [alloc::vec::Vec::index]: forward function
+let alloc_vec_Vec_index (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (self : alloc_vec_Vec t) (i : idx) : result inst.output =
+  admit () // TODO
+
+// [alloc::vec::Vec::index_mut]: forward function
+let alloc_vec_Vec_index_mut (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (self : alloc_vec_Vec t) (i : idx) : result inst.output =
+  admit () // TODO
+
+// [alloc::vec::Vec::index_mut]: backward function 0
+let alloc_vec_Vec_index_mut_back
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (self : alloc_vec_Vec t) (i : idx) (x : inst.output) : result (alloc_vec_Vec t) =
+  admit () // TODO
+
+// Trait implementation: [alloc::vec::Vec]
+let alloc_vec_Vec_coreopsindexIndexInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_Index (alloc_vec_Vec t) idx = {
+  output = inst.output;
+  index = alloc_vec_Vec_index t idx inst;
+}
+
+// Trait implementation: [alloc::vec::Vec]
+let alloc_vec_Vec_coreopsindexIndexMutInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_IndexMut (alloc_vec_Vec t) idx = {
+  indexInst = alloc_vec_Vec_coreopsindexIndexInst t idx inst;
+  index_mut = alloc_vec_Vec_index_mut t idx inst;
+  index_mut_back = alloc_vec_Vec_index_mut_back t idx inst;
+}
+
+(*** Theorems *)
+
+let alloc_vec_Vec_index_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
+  Lemma (
+    alloc_vec_Vec_index a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i ==
+      alloc_vec_Vec_index_usize v i)
+  [SMTPat (alloc_vec_Vec_index a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i)]
+  =
+  admit()
+
+let alloc_vec_Vec_index_mut_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
+  Lemma (
+    alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i ==
+      alloc_vec_Vec_index_usize v i)
+  [SMTPat (alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i)]
+  =
+  admit()
+
+let alloc_vec_Vec_index_mut_back_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) :
+  Lemma (
+    alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x ==
+      alloc_vec_Vec_update_usize v i x)
+  [SMTPat (alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x)]
+  =
+  admit()
diff --git a/tests/fstar-split/hashmap/Hashmap.Clauses.Template.fst b/tests/fstar-split/hashmap/Hashmap.Clauses.Template.fst
new file mode 100644
index 00000000..2733b371
--- /dev/null
+++ b/tests/fstar-split/hashmap/Hashmap.Clauses.Template.fst
@@ -0,0 +1,71 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [hashmap]: templates for the decreases clauses *)
+module Hashmap.Clauses.Template
+open Primitives
+open Hashmap.Types
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [hashmap::{hashmap::HashMap<T>}::allocate_slots]: decreases clause
+    Source: 'src/hashmap.rs', lines 50:4-56:5 *)
+unfold
+let hashMap_allocate_slots_loop_decreases (t : Type0)
+  (slots : alloc_vec_Vec (list_t t)) (n : usize) : nat =
+  admit ()
+
+(** [hashmap::{hashmap::HashMap<T>}::clear]: decreases clause
+    Source: 'src/hashmap.rs', lines 80:4-88:5 *)
+unfold
+let hashMap_clear_loop_decreases (t : Type0) (slots : alloc_vec_Vec (list_t t))
+  (i : usize) : nat =
+  admit ()
+
+(** [hashmap::{hashmap::HashMap<T>}::insert_in_list]: decreases clause
+    Source: 'src/hashmap.rs', lines 97:4-114:5 *)
+unfold
+let hashMap_insert_in_list_loop_decreases (t : Type0) (key : usize) (value : t)
+  (ls : list_t t) : nat =
+  admit ()
+
+(** [hashmap::{hashmap::HashMap<T>}::move_elements_from_list]: decreases clause
+    Source: 'src/hashmap.rs', lines 183:4-196:5 *)
+unfold
+let hashMap_move_elements_from_list_loop_decreases (t : Type0)
+  (ntable : hashMap_t t) (ls : list_t t) : nat =
+  admit ()
+
+(** [hashmap::{hashmap::HashMap<T>}::move_elements]: decreases clause
+    Source: 'src/hashmap.rs', lines 171:4-180:5 *)
+unfold
+let hashMap_move_elements_loop_decreases (t : Type0) (ntable : hashMap_t t)
+  (slots : alloc_vec_Vec (list_t t)) (i : usize) : nat =
+  admit ()
+
+(** [hashmap::{hashmap::HashMap<T>}::contains_key_in_list]: decreases clause
+    Source: 'src/hashmap.rs', lines 206:4-219:5 *)
+unfold
+let hashMap_contains_key_in_list_loop_decreases (t : Type0) (key : usize)
+  (ls : list_t t) : nat =
+  admit ()
+
+(** [hashmap::{hashmap::HashMap<T>}::get_in_list]: decreases clause
+    Source: 'src/hashmap.rs', lines 224:4-237:5 *)
+unfold
+let hashMap_get_in_list_loop_decreases (t : Type0) (key : usize)
+  (ls : list_t t) : nat =
+  admit ()
+
+(** [hashmap::{hashmap::HashMap<T>}::get_mut_in_list]: decreases clause
+    Source: 'src/hashmap.rs', lines 245:4-254:5 *)
+unfold
+let hashMap_get_mut_in_list_loop_decreases (t : Type0) (ls : list_t t)
+  (key : usize) : nat =
+  admit ()
+
+(** [hashmap::{hashmap::HashMap<T>}::remove_from_list]: decreases clause
+    Source: 'src/hashmap.rs', lines 265:4-291:5 *)
+unfold
+let hashMap_remove_from_list_loop_decreases (t : Type0) (key : usize)
+  (ls : list_t t) : nat =
+  admit ()
+
diff --git a/tests/fstar-split/hashmap/Hashmap.Clauses.fst b/tests/fstar-split/hashmap/Hashmap.Clauses.fst
new file mode 100644
index 00000000..6c699d05
--- /dev/null
+++ b/tests/fstar-split/hashmap/Hashmap.Clauses.fst
@@ -0,0 +1,61 @@
+(** [hashmap]: the decreases clauses *)
+module Hashmap.Clauses
+open Primitives
+open FStar.List.Tot
+open Hashmap.Types
+
+#set-options "--z3rlimit 50 --fuel 0 --ifuel 1"
+
+(** [hashmap::HashMap::allocate_slots]: decreases clause *)
+unfold
+let hashMap_allocate_slots_loop_decreases (t : Type0)
+  (slots : alloc_vec_Vec (list_t t)) (n : usize) : nat = n
+
+(** [hashmap::HashMap::clear]: decreases clause *)
+unfold
+let hashMap_clear_loop_decreases (t : Type0) (slots : alloc_vec_Vec (list_t t))
+  (i : usize) : nat =
+  if i < length slots then length slots - i else 0
+
+(** [hashmap::HashMap::insert_in_list]: decreases clause *)
+unfold
+let hashMap_insert_in_list_loop_decreases (t : Type0) (key : usize) (value : t)
+  (ls : list_t t) : list_t t =
+  ls
+
+(** [hashmap::HashMap::move_elements_from_list]: decreases clause *)
+unfold
+let hashMap_move_elements_from_list_loop_decreases (t : Type0)
+  (ntable : hashMap_t t) (ls : list_t t) : list_t t =
+  ls
+
+(** [hashmap::HashMap::move_elements]: decreases clause *)
+unfold
+let hashMap_move_elements_loop_decreases (t : Type0) (ntable : hashMap_t t)
+  (slots : alloc_vec_Vec (list_t t)) (i : usize) : nat =
+  if i < length slots then length slots - i else 0
+
+(** [hashmap::HashMap::contains_key_in_list]: decreases clause *)
+unfold
+let hashMap_contains_key_in_list_loop_decreases (t : Type0) (key : usize)
+  (ls : list_t t) : list_t t =
+  ls
+
+(** [hashmap::HashMap::get_in_list]: decreases clause *)
+unfold
+let hashMap_get_in_list_loop_decreases (t : Type0) (key : usize) (ls : list_t t) :
+  list_t t =
+  ls
+
+(** [hashmap::HashMap::get_mut_in_list]: decreases clause *)
+unfold
+let hashMap_get_mut_in_list_loop_decreases (t : Type0) (ls : list_t t)
+  (key : usize) : list_t t =
+  ls
+
+(** [hashmap::HashMap::remove_from_list]: decreases clause *)
+unfold
+let hashMap_remove_from_list_loop_decreases (t : Type0) (key : usize)
+  (ls : list_t t) : list_t t =
+  ls
+
diff --git a/tests/fstar-split/hashmap/Hashmap.Funs.fst b/tests/fstar-split/hashmap/Hashmap.Funs.fst
new file mode 100644
index 00000000..79327183
--- /dev/null
+++ b/tests/fstar-split/hashmap/Hashmap.Funs.fst
@@ -0,0 +1,529 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [hashmap]: function definitions *)
+module Hashmap.Funs
+open Primitives
+include Hashmap.Types
+include Hashmap.Clauses
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [hashmap::hash_key]: forward function
+    Source: 'src/hashmap.rs', lines 27:0-27:32 *)
+let hash_key (k : usize) : result usize =
+  Return k
+
+(** [hashmap::{hashmap::HashMap<T>}::allocate_slots]: loop 0: forward function
+    Source: 'src/hashmap.rs', lines 50:4-56:5 *)
+let rec hashMap_allocate_slots_loop
+  (t : Type0) (slots : alloc_vec_Vec (list_t t)) (n : usize) :
+  Tot (result (alloc_vec_Vec (list_t t)))
+  (decreases (hashMap_allocate_slots_loop_decreases t slots n))
+  =
+  if n > 0
+  then
+    let* slots1 = alloc_vec_Vec_push (list_t t) slots List_Nil in
+    let* n1 = usize_sub n 1 in
+    hashMap_allocate_slots_loop t slots1 n1
+  else Return slots
+
+(** [hashmap::{hashmap::HashMap<T>}::allocate_slots]: forward function
+    Source: 'src/hashmap.rs', lines 50:4-50:76 *)
+let hashMap_allocate_slots
+  (t : Type0) (slots : alloc_vec_Vec (list_t t)) (n : usize) :
+  result (alloc_vec_Vec (list_t t))
+  =
+  hashMap_allocate_slots_loop t slots n
+
+(** [hashmap::{hashmap::HashMap<T>}::new_with_capacity]: forward function
+    Source: 'src/hashmap.rs', lines 59:4-63:13 *)
+let hashMap_new_with_capacity
+  (t : Type0) (capacity : usize) (max_load_dividend : usize)
+  (max_load_divisor : usize) :
+  result (hashMap_t t)
+  =
+  let v = alloc_vec_Vec_new (list_t t) in
+  let* slots = hashMap_allocate_slots t v capacity in
+  let* i = usize_mul capacity max_load_dividend in
+  let* i1 = usize_div i max_load_divisor in
+  Return
+    {
+      num_entries = 0;
+      max_load_factor = (max_load_dividend, max_load_divisor);
+      max_load = i1;
+      slots = slots
+    }
+
+(** [hashmap::{hashmap::HashMap<T>}::new]: forward function
+    Source: 'src/hashmap.rs', lines 75:4-75:24 *)
+let hashMap_new (t : Type0) : result (hashMap_t t) =
+  hashMap_new_with_capacity t 32 4 5
+
+(** [hashmap::{hashmap::HashMap<T>}::clear]: loop 0: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/hashmap.rs', lines 80:4-88:5 *)
+let rec hashMap_clear_loop
+  (t : Type0) (slots : alloc_vec_Vec (list_t t)) (i : usize) :
+  Tot (result (alloc_vec_Vec (list_t t)))
+  (decreases (hashMap_clear_loop_decreases t slots i))
+  =
+  let i1 = alloc_vec_Vec_len (list_t t) slots in
+  if i < i1
+  then
+    let* i2 = usize_add i 1 in
+    let* slots1 =
+      alloc_vec_Vec_index_mut_back (list_t t) usize
+        (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) slots i
+        List_Nil in
+    hashMap_clear_loop t slots1 i2
+  else Return slots
+
+(** [hashmap::{hashmap::HashMap<T>}::clear]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/hashmap.rs', lines 80:4-80:27 *)
+let hashMap_clear (t : Type0) (self : hashMap_t t) : result (hashMap_t t) =
+  let* v = hashMap_clear_loop t self.slots 0 in
+  Return { self with num_entries = 0; slots = v }
+
+(** [hashmap::{hashmap::HashMap<T>}::len]: forward function
+    Source: 'src/hashmap.rs', lines 90:4-90:30 *)
+let hashMap_len (t : Type0) (self : hashMap_t t) : result usize =
+  Return self.num_entries
+
+(** [hashmap::{hashmap::HashMap<T>}::insert_in_list]: loop 0: forward function
+    Source: 'src/hashmap.rs', lines 97:4-114:5 *)
+let rec hashMap_insert_in_list_loop
+  (t : Type0) (key : usize) (value : t) (ls : list_t t) :
+  Tot (result bool)
+  (decreases (hashMap_insert_in_list_loop_decreases t key value ls))
+  =
+  begin match ls with
+  | List_Cons ckey _ tl ->
+    if ckey = key
+    then Return false
+    else hashMap_insert_in_list_loop t key value tl
+  | List_Nil -> Return true
+  end
+
+(** [hashmap::{hashmap::HashMap<T>}::insert_in_list]: forward function
+    Source: 'src/hashmap.rs', lines 97:4-97:71 *)
+let hashMap_insert_in_list
+  (t : Type0) (key : usize) (value : t) (ls : list_t t) : result bool =
+  hashMap_insert_in_list_loop t key value ls
+
+(** [hashmap::{hashmap::HashMap<T>}::insert_in_list]: loop 0: backward function 0
+    Source: 'src/hashmap.rs', lines 97:4-114:5 *)
+let rec hashMap_insert_in_list_loop_back
+  (t : Type0) (key : usize) (value : t) (ls : list_t t) :
+  Tot (result (list_t t))
+  (decreases (hashMap_insert_in_list_loop_decreases t key value ls))
+  =
+  begin match ls with
+  | List_Cons ckey cvalue tl ->
+    if ckey = key
+    then Return (List_Cons ckey value tl)
+    else
+      let* tl1 = hashMap_insert_in_list_loop_back t key value tl in
+      Return (List_Cons ckey cvalue tl1)
+  | List_Nil -> let l = List_Nil in Return (List_Cons key value l)
+  end
+
+(** [hashmap::{hashmap::HashMap<T>}::insert_in_list]: backward function 0
+    Source: 'src/hashmap.rs', lines 97:4-97:71 *)
+let hashMap_insert_in_list_back
+  (t : Type0) (key : usize) (value : t) (ls : list_t t) : result (list_t t) =
+  hashMap_insert_in_list_loop_back t key value ls
+
+(** [hashmap::{hashmap::HashMap<T>}::insert_no_resize]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/hashmap.rs', lines 117:4-117:54 *)
+let hashMap_insert_no_resize
+  (t : Type0) (self : hashMap_t t) (key : usize) (value : t) :
+  result (hashMap_t t)
+  =
+  let* hash = hash_key key in
+  let i = alloc_vec_Vec_len (list_t t) self.slots in
+  let* hash_mod = usize_rem hash i in
+  let* l =
+    alloc_vec_Vec_index_mut (list_t t) usize
+      (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
+      hash_mod in
+  let* inserted = hashMap_insert_in_list t key value l in
+  if inserted
+  then
+    let* i1 = usize_add self.num_entries 1 in
+    let* l1 = hashMap_insert_in_list_back t key value l in
+    let* v =
+      alloc_vec_Vec_index_mut_back (list_t t) usize
+        (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
+        hash_mod l1 in
+    Return { self with num_entries = i1; slots = v }
+  else
+    let* l1 = hashMap_insert_in_list_back t key value l in
+    let* v =
+      alloc_vec_Vec_index_mut_back (list_t t) usize
+        (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
+        hash_mod l1 in
+    Return { self with slots = v }
+
+(** [hashmap::{hashmap::HashMap<T>}::move_elements_from_list]: loop 0: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/hashmap.rs', lines 183:4-196:5 *)
+let rec hashMap_move_elements_from_list_loop
+  (t : Type0) (ntable : hashMap_t t) (ls : list_t t) :
+  Tot (result (hashMap_t t))
+  (decreases (hashMap_move_elements_from_list_loop_decreases t ntable ls))
+  =
+  begin match ls with
+  | List_Cons k v tl ->
+    let* ntable1 = hashMap_insert_no_resize t ntable k v in
+    hashMap_move_elements_from_list_loop t ntable1 tl
+  | List_Nil -> Return ntable
+  end
+
+(** [hashmap::{hashmap::HashMap<T>}::move_elements_from_list]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/hashmap.rs', lines 183:4-183:72 *)
+let hashMap_move_elements_from_list
+  (t : Type0) (ntable : hashMap_t t) (ls : list_t t) : result (hashMap_t t) =
+  hashMap_move_elements_from_list_loop t ntable ls
+
+(** [hashmap::{hashmap::HashMap<T>}::move_elements]: loop 0: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/hashmap.rs', lines 171:4-180:5 *)
+let rec hashMap_move_elements_loop
+  (t : Type0) (ntable : hashMap_t t) (slots : alloc_vec_Vec (list_t t))
+  (i : usize) :
+  Tot (result ((hashMap_t t) & (alloc_vec_Vec (list_t t))))
+  (decreases (hashMap_move_elements_loop_decreases t ntable slots i))
+  =
+  let i1 = alloc_vec_Vec_len (list_t t) slots in
+  if i < i1
+  then
+    let* l =
+      alloc_vec_Vec_index_mut (list_t t) usize
+        (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) slots i in
+    let ls = core_mem_replace (list_t t) l List_Nil in
+    let* ntable1 = hashMap_move_elements_from_list t ntable ls in
+    let* i2 = usize_add i 1 in
+    let l1 = core_mem_replace_back (list_t t) l List_Nil in
+    let* slots1 =
+      alloc_vec_Vec_index_mut_back (list_t t) usize
+        (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) slots i l1 in
+    hashMap_move_elements_loop t ntable1 slots1 i2
+  else Return (ntable, slots)
+
+(** [hashmap::{hashmap::HashMap<T>}::move_elements]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/hashmap.rs', lines 171:4-171:95 *)
+let hashMap_move_elements
+  (t : Type0) (ntable : hashMap_t t) (slots : alloc_vec_Vec (list_t t))
+  (i : usize) :
+  result ((hashMap_t t) & (alloc_vec_Vec (list_t t)))
+  =
+  hashMap_move_elements_loop t ntable slots i
+
+(** [hashmap::{hashmap::HashMap<T>}::try_resize]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/hashmap.rs', lines 140:4-140:28 *)
+let hashMap_try_resize
+  (t : Type0) (self : hashMap_t t) : result (hashMap_t t) =
+  let* max_usize = scalar_cast U32 Usize core_u32_max in
+  let capacity = alloc_vec_Vec_len (list_t t) self.slots in
+  let* n1 = usize_div max_usize 2 in
+  let (i, i1) = self.max_load_factor in
+  let* i2 = usize_div n1 i in
+  if capacity <= i2
+  then
+    let* i3 = usize_mul capacity 2 in
+    let* ntable = hashMap_new_with_capacity t i3 i i1 in
+    let* (ntable1, _) = hashMap_move_elements t ntable self.slots 0 in
+    Return
+      { ntable1 with num_entries = self.num_entries; max_load_factor = (i, i1)
+      }
+  else Return { self with max_load_factor = (i, i1) }
+
+(** [hashmap::{hashmap::HashMap<T>}::insert]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/hashmap.rs', lines 129:4-129:48 *)
+let hashMap_insert
+  (t : Type0) (self : hashMap_t t) (key : usize) (value : t) :
+  result (hashMap_t t)
+  =
+  let* self1 = hashMap_insert_no_resize t self key value in
+  let* i = hashMap_len t self1 in
+  if i > self1.max_load then hashMap_try_resize t self1 else Return self1
+
+(** [hashmap::{hashmap::HashMap<T>}::contains_key_in_list]: loop 0: forward function
+    Source: 'src/hashmap.rs', lines 206:4-219:5 *)
+let rec hashMap_contains_key_in_list_loop
+  (t : Type0) (key : usize) (ls : list_t t) :
+  Tot (result bool)
+  (decreases (hashMap_contains_key_in_list_loop_decreases t key ls))
+  =
+  begin match ls with
+  | List_Cons ckey _ tl ->
+    if ckey = key
+    then Return true
+    else hashMap_contains_key_in_list_loop t key tl
+  | List_Nil -> Return false
+  end
+
+(** [hashmap::{hashmap::HashMap<T>}::contains_key_in_list]: forward function
+    Source: 'src/hashmap.rs', lines 206:4-206:68 *)
+let hashMap_contains_key_in_list
+  (t : Type0) (key : usize) (ls : list_t t) : result bool =
+  hashMap_contains_key_in_list_loop t key ls
+
+(** [hashmap::{hashmap::HashMap<T>}::contains_key]: forward function
+    Source: 'src/hashmap.rs', lines 199:4-199:49 *)
+let hashMap_contains_key
+  (t : Type0) (self : hashMap_t t) (key : usize) : result bool =
+  let* hash = hash_key key in
+  let i = alloc_vec_Vec_len (list_t t) self.slots in
+  let* hash_mod = usize_rem hash i in
+  let* l =
+    alloc_vec_Vec_index (list_t t) usize
+      (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
+      hash_mod in
+  hashMap_contains_key_in_list t key l
+
+(** [hashmap::{hashmap::HashMap<T>}::get_in_list]: loop 0: forward function
+    Source: 'src/hashmap.rs', lines 224:4-237:5 *)
+let rec hashMap_get_in_list_loop
+  (t : Type0) (key : usize) (ls : list_t t) :
+  Tot (result t) (decreases (hashMap_get_in_list_loop_decreases t key ls))
+  =
+  begin match ls with
+  | List_Cons ckey cvalue tl ->
+    if ckey = key then Return cvalue else hashMap_get_in_list_loop t key tl
+  | List_Nil -> Fail Failure
+  end
+
+(** [hashmap::{hashmap::HashMap<T>}::get_in_list]: forward function
+    Source: 'src/hashmap.rs', lines 224:4-224:70 *)
+let hashMap_get_in_list (t : Type0) (key : usize) (ls : list_t t) : result t =
+  hashMap_get_in_list_loop t key ls
+
+(** [hashmap::{hashmap::HashMap<T>}::get]: forward function
+    Source: 'src/hashmap.rs', lines 239:4-239:55 *)
+let hashMap_get (t : Type0) (self : hashMap_t t) (key : usize) : result t =
+  let* hash = hash_key key in
+  let i = alloc_vec_Vec_len (list_t t) self.slots in
+  let* hash_mod = usize_rem hash i in
+  let* l =
+    alloc_vec_Vec_index (list_t t) usize
+      (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
+      hash_mod in
+  hashMap_get_in_list t key l
+
+(** [hashmap::{hashmap::HashMap<T>}::get_mut_in_list]: loop 0: forward function
+    Source: 'src/hashmap.rs', lines 245:4-254:5 *)
+let rec hashMap_get_mut_in_list_loop
+  (t : Type0) (ls : list_t t) (key : usize) :
+  Tot (result t) (decreases (hashMap_get_mut_in_list_loop_decreases t ls key))
+  =
+  begin match ls with
+  | List_Cons ckey cvalue tl ->
+    if ckey = key then Return cvalue else hashMap_get_mut_in_list_loop t tl key
+  | List_Nil -> Fail Failure
+  end
+
+(** [hashmap::{hashmap::HashMap<T>}::get_mut_in_list]: forward function
+    Source: 'src/hashmap.rs', lines 245:4-245:86 *)
+let hashMap_get_mut_in_list
+  (t : Type0) (ls : list_t t) (key : usize) : result t =
+  hashMap_get_mut_in_list_loop t ls key
+
+(** [hashmap::{hashmap::HashMap<T>}::get_mut_in_list]: loop 0: backward function 0
+    Source: 'src/hashmap.rs', lines 245:4-254:5 *)
+let rec hashMap_get_mut_in_list_loop_back
+  (t : Type0) (ls : list_t t) (key : usize) (ret : t) :
+  Tot (result (list_t t))
+  (decreases (hashMap_get_mut_in_list_loop_decreases t ls key))
+  =
+  begin match ls with
+  | List_Cons ckey cvalue tl ->
+    if ckey = key
+    then Return (List_Cons ckey ret tl)
+    else
+      let* tl1 = hashMap_get_mut_in_list_loop_back t tl key ret in
+      Return (List_Cons ckey cvalue tl1)
+  | List_Nil -> Fail Failure
+  end
+
+(** [hashmap::{hashmap::HashMap<T>}::get_mut_in_list]: backward function 0
+    Source: 'src/hashmap.rs', lines 245:4-245:86 *)
+let hashMap_get_mut_in_list_back
+  (t : Type0) (ls : list_t t) (key : usize) (ret : t) : result (list_t t) =
+  hashMap_get_mut_in_list_loop_back t ls key ret
+
+(** [hashmap::{hashmap::HashMap<T>}::get_mut]: forward function
+    Source: 'src/hashmap.rs', lines 257:4-257:67 *)
+let hashMap_get_mut (t : Type0) (self : hashMap_t t) (key : usize) : result t =
+  let* hash = hash_key key in
+  let i = alloc_vec_Vec_len (list_t t) self.slots in
+  let* hash_mod = usize_rem hash i in
+  let* l =
+    alloc_vec_Vec_index_mut (list_t t) usize
+      (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
+      hash_mod in
+  hashMap_get_mut_in_list t l key
+
+(** [hashmap::{hashmap::HashMap<T>}::get_mut]: backward function 0
+    Source: 'src/hashmap.rs', lines 257:4-257:67 *)
+let hashMap_get_mut_back
+  (t : Type0) (self : hashMap_t t) (key : usize) (ret : t) :
+  result (hashMap_t t)
+  =
+  let* hash = hash_key key in
+  let i = alloc_vec_Vec_len (list_t t) self.slots in
+  let* hash_mod = usize_rem hash i in
+  let* l =
+    alloc_vec_Vec_index_mut (list_t t) usize
+      (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
+      hash_mod in
+  let* l1 = hashMap_get_mut_in_list_back t l key ret in
+  let* v =
+    alloc_vec_Vec_index_mut_back (list_t t) usize
+      (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
+      hash_mod l1 in
+  Return { self with slots = v }
+
+(** [hashmap::{hashmap::HashMap<T>}::remove_from_list]: loop 0: forward function
+    Source: 'src/hashmap.rs', lines 265:4-291:5 *)
+let rec hashMap_remove_from_list_loop
+  (t : Type0) (key : usize) (ls : list_t t) :
+  Tot (result (option t))
+  (decreases (hashMap_remove_from_list_loop_decreases t key ls))
+  =
+  begin match ls with
+  | List_Cons ckey x tl ->
+    if ckey = key
+    then
+      let mv_ls = core_mem_replace (list_t t) (List_Cons ckey x tl) List_Nil in
+      begin match mv_ls with
+      | List_Cons _ cvalue _ -> Return (Some cvalue)
+      | List_Nil -> Fail Failure
+      end
+    else hashMap_remove_from_list_loop t key tl
+  | List_Nil -> Return None
+  end
+
+(** [hashmap::{hashmap::HashMap<T>}::remove_from_list]: forward function
+    Source: 'src/hashmap.rs', lines 265:4-265:69 *)
+let hashMap_remove_from_list
+  (t : Type0) (key : usize) (ls : list_t t) : result (option t) =
+  hashMap_remove_from_list_loop t key ls
+
+(** [hashmap::{hashmap::HashMap<T>}::remove_from_list]: loop 0: backward function 1
+    Source: 'src/hashmap.rs', lines 265:4-291:5 *)
+let rec hashMap_remove_from_list_loop_back
+  (t : Type0) (key : usize) (ls : list_t t) :
+  Tot (result (list_t t))
+  (decreases (hashMap_remove_from_list_loop_decreases t key ls))
+  =
+  begin match ls with
+  | List_Cons ckey x tl ->
+    if ckey = key
+    then
+      let mv_ls = core_mem_replace (list_t t) (List_Cons ckey x tl) List_Nil in
+      begin match mv_ls with
+      | List_Cons _ _ tl1 -> Return tl1
+      | List_Nil -> Fail Failure
+      end
+    else
+      let* tl1 = hashMap_remove_from_list_loop_back t key tl in
+      Return (List_Cons ckey x tl1)
+  | List_Nil -> Return List_Nil
+  end
+
+(** [hashmap::{hashmap::HashMap<T>}::remove_from_list]: backward function 1
+    Source: 'src/hashmap.rs', lines 265:4-265:69 *)
+let hashMap_remove_from_list_back
+  (t : Type0) (key : usize) (ls : list_t t) : result (list_t t) =
+  hashMap_remove_from_list_loop_back t key ls
+
+(** [hashmap::{hashmap::HashMap<T>}::remove]: forward function
+    Source: 'src/hashmap.rs', lines 294:4-294:52 *)
+let hashMap_remove
+  (t : Type0) (self : hashMap_t t) (key : usize) : result (option t) =
+  let* hash = hash_key key in
+  let i = alloc_vec_Vec_len (list_t t) self.slots in
+  let* hash_mod = usize_rem hash i in
+  let* l =
+    alloc_vec_Vec_index_mut (list_t t) usize
+      (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
+      hash_mod in
+  let* x = hashMap_remove_from_list t key l in
+  begin match x with
+  | None -> Return None
+  | Some x1 -> let* _ = usize_sub self.num_entries 1 in Return (Some x1)
+  end
+
+(** [hashmap::{hashmap::HashMap<T>}::remove]: backward function 0
+    Source: 'src/hashmap.rs', lines 294:4-294:52 *)
+let hashMap_remove_back
+  (t : Type0) (self : hashMap_t t) (key : usize) : result (hashMap_t t) =
+  let* hash = hash_key key in
+  let i = alloc_vec_Vec_len (list_t t) self.slots in
+  let* hash_mod = usize_rem hash i in
+  let* l =
+    alloc_vec_Vec_index_mut (list_t t) usize
+      (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
+      hash_mod in
+  let* x = hashMap_remove_from_list t key l in
+  begin match x with
+  | None ->
+    let* l1 = hashMap_remove_from_list_back t key l in
+    let* v =
+      alloc_vec_Vec_index_mut_back (list_t t) usize
+        (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
+        hash_mod l1 in
+    Return { self with slots = v }
+  | Some _ ->
+    let* i1 = usize_sub self.num_entries 1 in
+    let* l1 = hashMap_remove_from_list_back t key l in
+    let* v =
+      alloc_vec_Vec_index_mut_back (list_t t) usize
+        (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
+        hash_mod l1 in
+    Return { self with num_entries = i1; slots = v }
+  end
+
+(** [hashmap::test1]: forward function
+    Source: 'src/hashmap.rs', lines 315:0-315:10 *)
+let test1 : result unit =
+  let* hm = hashMap_new u64 in
+  let* hm1 = hashMap_insert u64 hm 0 42 in
+  let* hm2 = hashMap_insert u64 hm1 128 18 in
+  let* hm3 = hashMap_insert u64 hm2 1024 138 in
+  let* hm4 = hashMap_insert u64 hm3 1056 256 in
+  let* i = hashMap_get u64 hm4 128 in
+  if not (i = 18)
+  then Fail Failure
+  else
+    let* hm5 = hashMap_get_mut_back u64 hm4 1024 56 in
+    let* i1 = hashMap_get u64 hm5 1024 in
+    if not (i1 = 56)
+    then Fail Failure
+    else
+      let* x = hashMap_remove u64 hm5 1024 in
+      begin match x with
+      | None -> Fail Failure
+      | Some x1 ->
+        if not (x1 = 56)
+        then Fail Failure
+        else
+          let* hm6 = hashMap_remove_back u64 hm5 1024 in
+          let* i2 = hashMap_get u64 hm6 0 in
+          if not (i2 = 42)
+          then Fail Failure
+          else
+            let* i3 = hashMap_get u64 hm6 128 in
+            if not (i3 = 18)
+            then Fail Failure
+            else
+              let* i4 = hashMap_get u64 hm6 1056 in
+              if not (i4 = 256) then Fail Failure else Return ()
+      end
+
diff --git a/tests/fstar/hashmap/Hashmap.Properties.fst b/tests/fstar-split/hashmap/Hashmap.Properties.fst
index def520f0..def520f0 100644
--- a/tests/fstar/hashmap/Hashmap.Properties.fst
+++ b/tests/fstar-split/hashmap/Hashmap.Properties.fst
diff --git a/tests/fstar/hashmap/Hashmap.Properties.fsti b/tests/fstar-split/hashmap/Hashmap.Properties.fsti
index 26c0ec06..26c0ec06 100644
--- a/tests/fstar/hashmap/Hashmap.Properties.fsti
+++ b/tests/fstar-split/hashmap/Hashmap.Properties.fsti
diff --git a/tests/fstar-split/hashmap/Hashmap.Types.fst b/tests/fstar-split/hashmap/Hashmap.Types.fst
new file mode 100644
index 00000000..ef96b1e9
--- /dev/null
+++ b/tests/fstar-split/hashmap/Hashmap.Types.fst
@@ -0,0 +1,23 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [hashmap]: type definitions *)
+module Hashmap.Types
+open Primitives
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [hashmap::List]
+    Source: 'src/hashmap.rs', lines 19:0-19:16 *)
+type list_t (t : Type0) =
+| List_Cons : usize -> t -> list_t t -> list_t t
+| List_Nil : list_t t
+
+(** [hashmap::HashMap]
+    Source: 'src/hashmap.rs', lines 35:0-35:21 *)
+type hashMap_t (t : Type0) =
+{
+  num_entries : usize;
+  max_load_factor : (usize & usize);
+  max_load : usize;
+  slots : alloc_vec_Vec (list_t t);
+}
+
diff --git a/tests/fstar-split/hashmap/Makefile b/tests/fstar-split/hashmap/Makefile
new file mode 100644
index 00000000..fa7d1f36
--- /dev/null
+++ b/tests/fstar-split/hashmap/Makefile
@@ -0,0 +1,49 @@
+# This file was automatically generated - modify ../Makefile.template instead
+INCLUDE_DIRS = .
+
+FSTAR_INCLUDES = $(addprefix --include ,$(INCLUDE_DIRS))
+
+FSTAR_HINTS ?= --use_hints --use_hint_hashes --record_hints
+
+FSTAR_OPTIONS = $(FSTAR_HINTS) \
+  --cache_checked_modules $(FSTAR_INCLUDES) --cmi \
+  --warn_error '+241@247+285-274' \
+
+FSTAR_EXE ?= fstar.exe
+FSTAR_NO_FLAGS = $(FSTAR_EXE) --already_cached 'Prims FStar LowStar Steel' --odir obj --cache_dir obj
+
+FSTAR = $(FSTAR_NO_FLAGS) $(FSTAR_OPTIONS)
+
+# The F* roots are used to compute the dependency graph, and generate the .depend file
+FSTAR_ROOTS ?= $(wildcard *.fst *.fsti)
+
+# Build all the files
+all: $(addprefix obj/,$(addsuffix .checked,$(FSTAR_ROOTS)))
+
+# This is the right way to ensure the .depend file always gets re-built.
+ifeq (,$(filter %-in,$(MAKECMDGOALS)))
+ifndef NODEPEND
+ifndef MAKE_RESTARTS
+.depend: .FORCE
+	$(FSTAR_NO_FLAGS) --dep full $(notdir $(FSTAR_ROOTS)) > $@
+
+.PHONY: .FORCE
+.FORCE:
+endif
+endif
+
+include .depend
+endif
+
+# For the interactive mode
+%.fst-in %.fsti-in:
+	@echo $(FSTAR_OPTIONS)
+
+# Generete the .checked files in batch mode
+%.checked:
+	$(FSTAR) $(FSTAR_OPTIONS) $< && \
+	touch -c $@
+
+.PHONY: clean
+clean:
+	rm -f obj/*
diff --git a/tests/fstar-split/hashmap/Primitives.fst b/tests/fstar-split/hashmap/Primitives.fst
new file mode 100644
index 00000000..a3ffbde4
--- /dev/null
+++ b/tests/fstar-split/hashmap/Primitives.fst
@@ -0,0 +1,884 @@
+/// This file lists primitive and assumed functions and types
+module Primitives
+open FStar.Mul
+open FStar.List.Tot
+
+#set-options "--z3rlimit 15 --fuel 0 --ifuel 1"
+
+(*** Utilities *)
+val list_update (#a : Type0) (ls : list a) (i : nat{i < length ls}) (x : a) :
+  ls':list a{
+    length ls' = length ls /\
+    index ls' i == x
+  }
+#push-options "--fuel 1"
+let rec list_update #a ls i x =
+  match ls with
+  | x' :: ls -> if i = 0 then x :: ls else x' :: list_update ls (i-1) x
+#pop-options
+
+(*** Result *)
+type error : Type0 =
+| Failure
+| OutOfFuel
+
+type result (a : Type0) : Type0 =
+| Return : v:a -> result a
+| Fail : e:error -> result a
+
+// Monadic return operator
+unfold let return (#a : Type0) (x : a) : result a = Return x
+
+// Monadic bind operator.
+// Allows to use the notation:
+// ```
+// let* x = y in
+// ...
+// ```
+unfold let (let*) (#a #b : Type0) (m: result a)
+  (f: (x:a) -> Pure (result b) (requires (m == Return x)) (ensures fun _ -> True)) :
+  result b =
+  match m with
+  | Return x -> f x
+  | Fail e   -> Fail e
+
+// Monadic assert(...)
+let massert (b:bool) : result unit = if b then Return () else Fail Failure
+
+// Normalize and unwrap a successful result (used for globals).
+let eval_global (#a : Type0) (x : result a{Return? (normalize_term x)}) : a = Return?.v x
+
+(*** Misc *)
+type char = FStar.Char.char
+type string = string
+
+let is_zero (n: nat) : bool = n = 0
+let decrease (n: nat{n > 0}) : nat = n - 1
+
+let core_mem_replace (a : Type0) (x : a) (y : a) : a = x
+let core_mem_replace_back (a : Type0) (x : a) (y : a) : a = y
+
+// We don't really use raw pointers for now
+type mut_raw_ptr (t : Type0) = { v : t }
+type const_raw_ptr (t : Type0) = { v : t }
+
+(*** Scalars *)
+/// Rem.: most of the following code was partially generated
+
+assume val size_numbits : pos
+
+// TODO: we could use FStar.Int.int_t and FStar.UInt.int_t
+
+let isize_min : int = -9223372036854775808 // TODO: should be opaque
+let isize_max : int = 9223372036854775807 // TODO: should be opaque
+let i8_min : int = -128
+let i8_max : int = 127
+let i16_min : int = -32768
+let i16_max : int = 32767
+let i32_min : int = -2147483648
+let i32_max : int = 2147483647
+let i64_min : int = -9223372036854775808
+let i64_max : int = 9223372036854775807
+let i128_min : int = -170141183460469231731687303715884105728
+let i128_max : int = 170141183460469231731687303715884105727
+let usize_min : int = 0
+let usize_max : int = 4294967295 // TODO: should be opaque
+let u8_min : int = 0
+let u8_max : int = 255
+let u16_min : int = 0
+let u16_max : int = 65535
+let u32_min : int = 0
+let u32_max : int = 4294967295
+let u64_min : int = 0
+let u64_max : int = 18446744073709551615
+let u128_min : int = 0
+let u128_max : int = 340282366920938463463374607431768211455
+
+type scalar_ty =
+| Isize
+| I8
+| I16
+| I32
+| I64
+| I128
+| Usize
+| U8
+| U16
+| U32
+| U64
+| U128
+
+let is_unsigned = function
+  | Isize | I8 | I16 | I32 | I64 | I128 -> false
+  | Usize | U8 | U16 | U32 | U64 | U128 -> true
+
+let scalar_min (ty : scalar_ty) : int =
+  match ty with
+  | Isize -> isize_min
+  | I8 -> i8_min
+  | I16 -> i16_min
+  | I32 -> i32_min
+  | I64 -> i64_min
+  | I128 -> i128_min
+  | Usize -> usize_min
+  | U8 -> u8_min
+  | U16 -> u16_min
+  | U32 -> u32_min
+  | U64 -> u64_min
+  | U128 -> u128_min
+
+let scalar_max (ty : scalar_ty) : int =
+  match ty with
+  | Isize -> isize_max
+  | I8 -> i8_max
+  | I16 -> i16_max
+  | I32 -> i32_max
+  | I64 -> i64_max
+  | I128 -> i128_max
+  | Usize -> usize_max
+  | U8 -> u8_max
+  | U16 -> u16_max
+  | U32 -> u32_max
+  | U64 -> u64_max
+  | U128 -> u128_max
+
+type scalar (ty : scalar_ty) : eqtype = x:int{scalar_min ty <= x && x <= scalar_max ty}
+
+let mk_scalar (ty : scalar_ty) (x : int) : result (scalar ty) =
+  if scalar_min ty <= x && scalar_max ty >= x then Return x else Fail Failure
+
+let scalar_neg (#ty : scalar_ty) (x : scalar ty) : result (scalar ty) = mk_scalar ty (-x)
+
+let scalar_div (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  if y <> 0 then mk_scalar ty (x / y) else Fail Failure
+
+/// The remainder operation
+let int_rem (x : int) (y : int{y <> 0}) : int =
+  if x >= 0 then (x % y) else -(x % y)
+
+(* Checking consistency with Rust *)
+let _ = assert_norm(int_rem 1 2 = 1)
+let _ = assert_norm(int_rem (-1) 2 = -1)
+let _ = assert_norm(int_rem 1 (-2) = 1)
+let _ = assert_norm(int_rem (-1) (-2) = -1)
+
+let scalar_rem (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  if y <> 0 then mk_scalar ty (int_rem x y) else Fail Failure
+
+let scalar_add (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  mk_scalar ty (x + y)
+
+let scalar_sub (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  mk_scalar ty (x - y)
+
+let scalar_mul (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  mk_scalar ty (x * y)
+
+let scalar_xor (#ty : scalar_ty)
+    (x : scalar ty) (y : scalar ty) : scalar ty =
+  match ty with
+  | U8 -> FStar.UInt.logxor #8 x y
+  | U16 -> FStar.UInt.logxor #16 x y
+  | U32 -> FStar.UInt.logxor #32 x y
+  | U64 -> FStar.UInt.logxor #64 x y
+  | U128 -> FStar.UInt.logxor #128 x y
+  | Usize -> admit() // TODO
+  | I8 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 8);
+    normalize_spec (scalar I8);
+    FStar.Int.logxor #8 x y
+  | I16 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 16);
+    normalize_spec (scalar I16);
+    FStar.Int.logxor #16 x y
+  | I32 -> FStar.Int.logxor #32 x y
+  | I64 -> FStar.Int.logxor #64 x y
+  | I128 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 128);
+    normalize_spec (scalar I128);
+    FStar.Int.logxor #128 x y
+  | Isize -> admit() // TODO
+
+let scalar_or (#ty : scalar_ty)
+    (x : scalar ty) (y : scalar ty) : scalar ty =
+  match ty with
+  | U8 -> FStar.UInt.logor #8 x y
+  | U16 -> FStar.UInt.logor #16 x y
+  | U32 -> FStar.UInt.logor #32 x y
+  | U64 -> FStar.UInt.logor #64 x y
+  | U128 -> FStar.UInt.logor #128 x y
+  | Usize -> admit() // TODO
+  | I8 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 8);
+    normalize_spec (scalar I8);
+    FStar.Int.logor #8 x y
+  | I16 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 16);
+    normalize_spec (scalar I16);
+    FStar.Int.logor #16 x y
+  | I32 -> FStar.Int.logor #32 x y
+  | I64 -> FStar.Int.logor #64 x y
+  | I128 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 128);
+    normalize_spec (scalar I128);
+    FStar.Int.logor #128 x y
+  | Isize -> admit() // TODO
+
+let scalar_and (#ty : scalar_ty)
+    (x : scalar ty) (y : scalar ty) : scalar ty =
+  match ty with
+  | U8 -> FStar.UInt.logand #8 x y
+  | U16 -> FStar.UInt.logand #16 x y
+  | U32 -> FStar.UInt.logand #32 x y
+  | U64 -> FStar.UInt.logand #64 x y
+  | U128 -> FStar.UInt.logand #128 x y
+  | Usize -> admit() // TODO
+  | I8 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 8);
+    normalize_spec (scalar I8);
+    FStar.Int.logand #8 x y
+  | I16 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 16);
+    normalize_spec (scalar I16);
+    FStar.Int.logand #16 x y
+  | I32 -> FStar.Int.logand #32 x y
+  | I64 -> FStar.Int.logand #64 x y
+  | I128 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 128);
+    normalize_spec (scalar I128);
+    FStar.Int.logand #128 x y
+  | Isize -> admit() // TODO
+
+// Shift left
+let scalar_shl (#ty0 #ty1 : scalar_ty)
+    (x : scalar ty0) (y : scalar ty1) : result (scalar ty0) =
+  admit()
+
+// Shift right
+let scalar_shr (#ty0 #ty1 : scalar_ty)
+    (x : scalar ty0) (y : scalar ty1) : result (scalar ty0) =
+  admit()
+
+(** Cast an integer from a [src_ty] to a [tgt_ty] *)
+// TODO: check the semantics of casts in Rust
+let scalar_cast (src_ty : scalar_ty) (tgt_ty : scalar_ty) (x : scalar src_ty) : result (scalar tgt_ty) =
+  mk_scalar tgt_ty x
+
+// This can't fail, but for now we make all casts faillible (easier for the translation)
+let scalar_cast_bool (tgt_ty : scalar_ty) (x : bool) : result (scalar tgt_ty) =
+  mk_scalar tgt_ty (if x then 1 else 0)
+
+/// The scalar types
+type isize : eqtype = scalar Isize
+type i8    : eqtype = scalar I8
+type i16   : eqtype = scalar I16
+type i32   : eqtype = scalar I32
+type i64   : eqtype = scalar I64
+type i128  : eqtype = scalar I128
+type usize : eqtype = scalar Usize
+type u8    : eqtype = scalar U8
+type u16   : eqtype = scalar U16
+type u32   : eqtype = scalar U32
+type u64   : eqtype = scalar U64
+type u128  : eqtype = scalar U128
+
+
+let core_isize_min : isize = isize_min
+let core_isize_max : isize = isize_max
+let core_i8_min    : i8 = i8_min
+let core_i8_max    : i8 = i8_max
+let core_i16_min   : i16 = i16_min
+let core_i16_max   : i16 = i16_max
+let core_i32_min   : i32 = i32_min
+let core_i32_max   : i32 = i32_max
+let core_i64_min   : i64 = i64_min
+let core_i64_max   : i64 = i64_max
+let core_i128_min  : i128 = i128_min
+let core_i128_max  : i128 = i128_max
+
+let core_usize_min : usize = usize_min
+let core_usize_max : usize = usize_max
+let core_u8_min    : u8 = u8_min
+let core_u8_max    : u8 = u8_max
+let core_u16_min   : u16 = u16_min
+let core_u16_max   : u16 = u16_max
+let core_u32_min   : u32 = u32_min
+let core_u32_max   : u32 = u32_max
+let core_u64_min   : u64 = u64_min
+let core_u64_max   : u64 = u64_max
+let core_u128_min  : u128 = u128_min
+let core_u128_max  : u128 = u128_max
+
+/// Negation
+let isize_neg = scalar_neg #Isize
+let i8_neg = scalar_neg #I8
+let i16_neg = scalar_neg #I16
+let i32_neg = scalar_neg #I32
+let i64_neg = scalar_neg #I64
+let i128_neg = scalar_neg #I128
+
+/// Division
+let isize_div = scalar_div #Isize
+let i8_div = scalar_div #I8
+let i16_div = scalar_div #I16
+let i32_div = scalar_div #I32
+let i64_div = scalar_div #I64
+let i128_div = scalar_div #I128
+let usize_div = scalar_div #Usize
+let u8_div = scalar_div #U8
+let u16_div = scalar_div #U16
+let u32_div = scalar_div #U32
+let u64_div = scalar_div #U64
+let u128_div = scalar_div #U128
+
+/// Remainder
+let isize_rem = scalar_rem #Isize
+let i8_rem = scalar_rem #I8
+let i16_rem = scalar_rem #I16
+let i32_rem = scalar_rem #I32
+let i64_rem = scalar_rem #I64
+let i128_rem = scalar_rem #I128
+let usize_rem = scalar_rem #Usize
+let u8_rem = scalar_rem #U8
+let u16_rem = scalar_rem #U16
+let u32_rem = scalar_rem #U32
+let u64_rem = scalar_rem #U64
+let u128_rem = scalar_rem #U128
+
+/// Addition
+let isize_add = scalar_add #Isize
+let i8_add = scalar_add #I8
+let i16_add = scalar_add #I16
+let i32_add = scalar_add #I32
+let i64_add = scalar_add #I64
+let i128_add = scalar_add #I128
+let usize_add = scalar_add #Usize
+let u8_add = scalar_add #U8
+let u16_add = scalar_add #U16
+let u32_add = scalar_add #U32
+let u64_add = scalar_add #U64
+let u128_add = scalar_add #U128
+
+/// Subtraction
+let isize_sub = scalar_sub #Isize
+let i8_sub = scalar_sub #I8
+let i16_sub = scalar_sub #I16
+let i32_sub = scalar_sub #I32
+let i64_sub = scalar_sub #I64
+let i128_sub = scalar_sub #I128
+let usize_sub = scalar_sub #Usize
+let u8_sub = scalar_sub #U8
+let u16_sub = scalar_sub #U16
+let u32_sub = scalar_sub #U32
+let u64_sub = scalar_sub #U64
+let u128_sub = scalar_sub #U128
+
+/// Multiplication
+let isize_mul = scalar_mul #Isize
+let i8_mul = scalar_mul #I8
+let i16_mul = scalar_mul #I16
+let i32_mul = scalar_mul #I32
+let i64_mul = scalar_mul #I64
+let i128_mul = scalar_mul #I128
+let usize_mul = scalar_mul #Usize
+let u8_mul = scalar_mul #U8
+let u16_mul = scalar_mul #U16
+let u32_mul = scalar_mul #U32
+let u64_mul = scalar_mul #U64
+let u128_mul = scalar_mul #U128
+
+/// Xor
+let u8_xor = scalar_xor #U8
+let u16_xor = scalar_xor #U16
+let u32_xor = scalar_xor #U32
+let u64_xor = scalar_xor #U64
+let u128_xor = scalar_xor #U128
+let usize_xor = scalar_xor #Usize
+let i8_xor = scalar_xor #I8
+let i16_xor = scalar_xor #I16
+let i32_xor = scalar_xor #I32
+let i64_xor = scalar_xor #I64
+let i128_xor = scalar_xor #I128
+let isize_xor = scalar_xor #Isize
+
+/// Or
+let u8_or = scalar_or #U8
+let u16_or = scalar_or #U16
+let u32_or = scalar_or #U32
+let u64_or = scalar_or #U64
+let u128_or = scalar_or #U128
+let usize_or = scalar_or #Usize
+let i8_or = scalar_or #I8
+let i16_or = scalar_or #I16
+let i32_or = scalar_or #I32
+let i64_or = scalar_or #I64
+let i128_or = scalar_or #I128
+let isize_or = scalar_or #Isize
+
+/// And
+let u8_and = scalar_and #U8
+let u16_and = scalar_and #U16
+let u32_and = scalar_and #U32
+let u64_and = scalar_and #U64
+let u128_and = scalar_and #U128
+let usize_and = scalar_and #Usize
+let i8_and = scalar_and #I8
+let i16_and = scalar_and #I16
+let i32_and = scalar_and #I32
+let i64_and = scalar_and #I64
+let i128_and = scalar_and #I128
+let isize_and = scalar_and #Isize
+
+/// Shift left
+let u8_shl #ty = scalar_shl #U8 #ty
+let u16_shl #ty = scalar_shl #U16 #ty
+let u32_shl #ty = scalar_shl #U32 #ty
+let u64_shl #ty = scalar_shl #U64 #ty
+let u128_shl #ty = scalar_shl #U128 #ty
+let usize_shl #ty = scalar_shl #Usize #ty
+let i8_shl #ty = scalar_shl #I8 #ty
+let i16_shl #ty = scalar_shl #I16 #ty
+let i32_shl #ty = scalar_shl #I32 #ty
+let i64_shl #ty = scalar_shl #I64 #ty
+let i128_shl #ty = scalar_shl #I128 #ty
+let isize_shl #ty = scalar_shl #Isize #ty
+
+/// Shift right
+let u8_shr #ty = scalar_shr #U8 #ty
+let u16_shr #ty = scalar_shr #U16 #ty
+let u32_shr #ty = scalar_shr #U32 #ty
+let u64_shr #ty = scalar_shr #U64 #ty
+let u128_shr #ty = scalar_shr #U128 #ty
+let usize_shr #ty = scalar_shr #Usize #ty
+let i8_shr #ty = scalar_shr #I8 #ty
+let i16_shr #ty = scalar_shr #I16 #ty
+let i32_shr #ty = scalar_shr #I32 #ty
+let i64_shr #ty = scalar_shr #I64 #ty
+let i128_shr #ty = scalar_shr #I128 #ty
+let isize_shr #ty = scalar_shr #Isize #ty
+
+(*** core::ops *)
+
+// Trait declaration: [core::ops::index::Index]
+noeq type core_ops_index_Index (self idx : Type0) = {
+  output : Type0;
+  index : self → idx → result output
+}
+
+// Trait declaration: [core::ops::index::IndexMut]
+noeq type core_ops_index_IndexMut (self idx : Type0) = {
+  indexInst : core_ops_index_Index self idx;
+  index_mut : self → idx → result indexInst.output;
+  index_mut_back : self → idx → indexInst.output → result self;
+}
+
+// Trait declaration [core::ops::deref::Deref]
+noeq type core_ops_deref_Deref (self : Type0) = {
+  target : Type0;
+  deref : self → result target;
+}
+
+// Trait declaration [core::ops::deref::DerefMut]
+noeq type core_ops_deref_DerefMut (self : Type0) = {
+  derefInst : core_ops_deref_Deref self;
+  deref_mut : self → result derefInst.target;
+  deref_mut_back : self → derefInst.target → result self;
+}
+
+type core_ops_range_Range (a : Type0) = {
+  start : a;
+  end_ : a;
+}
+
+(*** [alloc] *)
+
+let alloc_boxed_Box_deref (t : Type0) (x : t) : result t = Return x
+let alloc_boxed_Box_deref_mut (t : Type0) (x : t) : result t = Return x
+let alloc_boxed_Box_deref_mut_back (t : Type) (_ : t) (x : t) : result t = Return x
+
+// Trait instance
+let alloc_boxed_Box_coreopsDerefInst (self : Type0) : core_ops_deref_Deref self = {
+  target = self;
+  deref = alloc_boxed_Box_deref self;
+}
+
+// Trait instance
+let alloc_boxed_Box_coreopsDerefMutInst (self : Type0) : core_ops_deref_DerefMut self = {
+  derefInst = alloc_boxed_Box_coreopsDerefInst self;
+  deref_mut = alloc_boxed_Box_deref_mut self;
+  deref_mut_back = alloc_boxed_Box_deref_mut_back self;
+}
+
+(*** Array *)
+type array (a : Type0) (n : usize) = s:list a{length s = n}
+
+// We tried putting the normalize_term condition as a refinement on the list
+// but it didn't work. It works with the requires clause.
+let mk_array (a : Type0) (n : usize)
+  (l : list a) :
+  Pure (array a n)
+  (requires (normalize_term(FStar.List.Tot.length l) = n))
+  (ensures (fun _ -> True)) =
+  normalize_term_spec (FStar.List.Tot.length l);
+  l
+
+let array_index_usize (a : Type0) (n : usize) (x : array a n) (i : usize) : result a =
+  if i < length x then Return (index x i)
+  else Fail Failure
+
+let array_update_usize (a : Type0) (n : usize) (x : array a n) (i : usize) (nx : a) : result (array a n) =
+  if i < length x then Return (list_update x i nx)
+  else Fail Failure
+
+(*** Slice *)
+type slice (a : Type0) = s:list a{length s <= usize_max}
+
+let slice_len (a : Type0) (s : slice a) : usize = length s
+
+let slice_index_usize (a : Type0) (x : slice a) (i : usize) : result a =
+  if i < length x then Return (index x i)
+  else Fail Failure
+
+let slice_update_usize (a : Type0) (x : slice a) (i : usize) (nx : a) : result (slice a) =
+  if i < length x then Return (list_update x i nx)
+  else Fail Failure
+
+(*** Subslices *)
+
+let array_to_slice (a : Type0) (n : usize) (x : array a n) : result (slice a) = Return x
+let array_from_slice (a : Type0) (n : usize) (x : array a n) (s : slice a) : result (array a n) =
+  if length s = n then Return s
+  else Fail Failure
+
+// TODO: finish the definitions below (there lacks [List.drop] and [List.take] in the standard library *)
+let array_subslice (a : Type0) (n : usize) (x : array a n) (r : core_ops_range_Range usize) : result (slice a) =
+  admit()
+
+let array_update_subslice (a : Type0) (n : usize) (x : array a n) (r : core_ops_range_Range usize) (ns : slice a) : result (array a n) =
+  admit()
+
+let array_repeat (a : Type0) (n : usize) (x : a) : array a n =
+  admit()
+
+let slice_subslice (a : Type0) (x : slice a) (r : core_ops_range_Range usize) : result (slice a) =
+  admit()
+
+let slice_update_subslice (a : Type0) (x : slice a) (r : core_ops_range_Range usize) (ns : slice a) : result (slice a) =
+  admit()
+
+(*** Vector *)
+type alloc_vec_Vec (a : Type0) = v:list a{length v <= usize_max}
+
+let alloc_vec_Vec_new (a  : Type0) : alloc_vec_Vec a = assert_norm(length #a [] == 0); []
+let alloc_vec_Vec_len (a : Type0) (v : alloc_vec_Vec a) : usize = length v
+
+// Helper
+let alloc_vec_Vec_index_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) : result a =
+  if i < length v then Return (index v i) else Fail Failure
+// Helper
+let alloc_vec_Vec_update_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
+  if i < length v then Return (list_update v i x) else Fail Failure
+
+// The **forward** function shouldn't be used
+let alloc_vec_Vec_push_fwd (a  : Type0) (v : alloc_vec_Vec a) (x : a) : unit = ()
+let alloc_vec_Vec_push (a  : Type0) (v : alloc_vec_Vec a) (x : a) :
+  Pure (result (alloc_vec_Vec a))
+  (requires True)
+  (ensures (fun res ->
+    match res with
+    | Fail e -> e == Failure
+    | Return v' -> length v' = length v + 1)) =
+  if length v < usize_max then begin
+    (**) assert_norm(length [x] == 1);
+    (**) append_length v [x];
+    (**) assert(length (append v [x]) = length v + 1);
+    Return (append v [x])
+    end
+  else Fail Failure
+
+// The **forward** function shouldn't be used
+let alloc_vec_Vec_insert_fwd (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result unit =
+  if i < length v then Return () else Fail Failure
+let alloc_vec_Vec_insert (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
+  if i < length v then Return (list_update v i x) else Fail Failure
+
+// Trait declaration: [core::slice::index::private_slice_index::Sealed]
+type core_slice_index_private_slice_index_Sealed (self : Type0) = unit
+
+// Trait declaration: [core::slice::index::SliceIndex]
+noeq type core_slice_index_SliceIndex (self t : Type0) = {
+  sealedInst : core_slice_index_private_slice_index_Sealed self;
+  output : Type0;
+  get : self → t → result (option output);
+  get_mut : self → t → result (option output);
+  get_mut_back : self → t → option output → result t;
+  get_unchecked : self → const_raw_ptr t → result (const_raw_ptr output);
+  get_unchecked_mut : self → mut_raw_ptr t → result (mut_raw_ptr output);
+  index : self → t → result output;
+  index_mut : self → t → result output;
+  index_mut_back : self → t → output → result t;
+}
+
+// [core::slice::index::[T]::index]: forward function
+let core_slice_index_Slice_index
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (s : slice t) (i : idx) : result inst.output =
+  let* x = inst.get i s in
+  match x with
+  | None -> Fail Failure
+  | Some x -> Return x
+
+// [core::slice::index::Range:::get]: forward function
+let core_slice_index_RangeUsize_get (t : Type0) (i : core_ops_range_Range usize) (s : slice t) :
+  result (option (slice t)) =
+  admit () // TODO
+
+// [core::slice::index::Range::get_mut]: forward function
+let core_slice_index_RangeUsize_get_mut
+  (t : Type0) : core_ops_range_Range usize → slice t → result (option (slice t)) =
+  admit () // TODO
+
+// [core::slice::index::Range::get_mut]: backward function 0
+let core_slice_index_RangeUsize_get_mut_back
+  (t : Type0) :
+  core_ops_range_Range usize → slice t → option (slice t) → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::Range::get_unchecked]: forward function
+let core_slice_index_RangeUsize_get_unchecked
+  (t : Type0) :
+  core_ops_range_Range usize → const_raw_ptr (slice t) → result (const_raw_ptr (slice t)) =
+  // Don't know what the model should be - for now we always fail to make
+  // sure code which uses it fails
+  fun _ _ -> Fail Failure
+
+// [core::slice::index::Range::get_unchecked_mut]: forward function
+let core_slice_index_RangeUsize_get_unchecked_mut
+  (t : Type0) :
+  core_ops_range_Range usize → mut_raw_ptr (slice t) → result (mut_raw_ptr (slice t)) =
+  // Don't know what the model should be - for now we always fail to make
+  // sure code which uses it fails
+  fun _ _ -> Fail Failure
+
+// [core::slice::index::Range::index]: forward function
+let core_slice_index_RangeUsize_index
+  (t : Type0) : core_ops_range_Range usize → slice t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::Range::index_mut]: forward function
+let core_slice_index_RangeUsize_index_mut
+  (t : Type0) : core_ops_range_Range usize → slice t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::Range::index_mut]: backward function 0
+let core_slice_index_RangeUsize_index_mut_back
+  (t : Type0) : core_ops_range_Range usize → slice t → slice t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::[T]::index_mut]: forward function
+let core_slice_index_Slice_index_mut
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
+  slice t → idx → result inst.output =
+  admit () // 
+
+// [core::slice::index::[T]::index_mut]: backward function 0
+let core_slice_index_Slice_index_mut_back
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
+  slice t → idx → inst.output → result (slice t) =
+  admit () // TODO
+
+// [core::array::[T; N]::index]: forward function
+let core_array_Array_index
+  (t idx : Type0) (n : usize) (inst : core_ops_index_Index (slice t) idx)
+  (a : array t n) (i : idx) : result inst.output =
+  admit () // TODO
+
+// [core::array::[T; N]::index_mut]: forward function
+let core_array_Array_index_mut
+  (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
+  (a : array t n) (i : idx) : result inst.indexInst.output =
+  admit () // TODO
+
+// [core::array::[T; N]::index_mut]: backward function 0
+let core_array_Array_index_mut_back
+  (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
+  (a : array t n) (i : idx) (x : inst.indexInst.output) : result (array t n) =
+  admit () // TODO
+
+// Trait implementation: [core::slice::index::private_slice_index::Range]
+let core_slice_index_private_slice_index_SealedRangeUsizeInst
+  : core_slice_index_private_slice_index_Sealed (core_ops_range_Range usize) = ()
+
+// Trait implementation: [core::slice::index::Range]
+let core_slice_index_SliceIndexRangeUsizeSliceTInst (t : Type0) :
+  core_slice_index_SliceIndex (core_ops_range_Range usize) (slice t) = {
+  sealedInst = core_slice_index_private_slice_index_SealedRangeUsizeInst;
+  output = slice t;
+  get = core_slice_index_RangeUsize_get t;
+  get_mut = core_slice_index_RangeUsize_get_mut t;
+  get_mut_back = core_slice_index_RangeUsize_get_mut_back t;
+  get_unchecked = core_slice_index_RangeUsize_get_unchecked t;
+  get_unchecked_mut = core_slice_index_RangeUsize_get_unchecked_mut t;
+  index = core_slice_index_RangeUsize_index t;
+  index_mut = core_slice_index_RangeUsize_index_mut t;
+  index_mut_back = core_slice_index_RangeUsize_index_mut_back t;
+}
+
+// Trait implementation: [core::slice::index::[T]]
+let core_ops_index_IndexSliceTIInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_Index (slice t) idx = {
+  output = inst.output;
+  index = core_slice_index_Slice_index t idx inst;
+}
+
+// Trait implementation: [core::slice::index::[T]]
+let core_ops_index_IndexMutSliceTIInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_IndexMut (slice t) idx = {
+  indexInst = core_ops_index_IndexSliceTIInst t idx inst;
+  index_mut = core_slice_index_Slice_index_mut t idx inst;
+  index_mut_back = core_slice_index_Slice_index_mut_back t idx inst;
+}
+
+// Trait implementation: [core::array::[T; N]]
+let core_ops_index_IndexArrayInst (t idx : Type0) (n : usize)
+  (inst : core_ops_index_Index (slice t) idx) :
+  core_ops_index_Index (array t n) idx = {
+  output = inst.output;
+  index = core_array_Array_index t idx n inst;
+}
+
+// Trait implementation: [core::array::[T; N]]
+let core_ops_index_IndexMutArrayIInst (t idx : Type0) (n : usize)
+  (inst : core_ops_index_IndexMut (slice t) idx) :
+  core_ops_index_IndexMut (array t n) idx = {
+  indexInst = core_ops_index_IndexArrayInst t idx n inst.indexInst;
+  index_mut = core_array_Array_index_mut t idx n inst;
+  index_mut_back = core_array_Array_index_mut_back t idx n inst;
+}
+
+// [core::slice::index::usize::get]: forward function
+let core_slice_index_usize_get
+  (t : Type0) : usize → slice t → result (option t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_mut]: forward function
+let core_slice_index_usize_get_mut
+  (t : Type0) : usize → slice t → result (option t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_mut]: backward function 0
+let core_slice_index_usize_get_mut_back
+  (t : Type0) : usize → slice t → option t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_unchecked]: forward function
+let core_slice_index_usize_get_unchecked
+  (t : Type0) : usize → const_raw_ptr (slice t) → result (const_raw_ptr t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_unchecked_mut]: forward function
+let core_slice_index_usize_get_unchecked_mut
+  (t : Type0) : usize → mut_raw_ptr (slice t) → result (mut_raw_ptr t) =
+  admit () // TODO
+
+// [core::slice::index::usize::index]: forward function
+let core_slice_index_usize_index (t : Type0) : usize → slice t → result t =
+  admit () // TODO
+
+// [core::slice::index::usize::index_mut]: forward function
+let core_slice_index_usize_index_mut (t : Type0) : usize → slice t → result t =
+  admit () // TODO
+
+// [core::slice::index::usize::index_mut]: backward function 0
+let core_slice_index_usize_index_mut_back
+  (t : Type0) : usize → slice t → t → result (slice t) =
+  admit () // TODO
+
+// Trait implementation: [core::slice::index::private_slice_index::usize]
+let core_slice_index_private_slice_index_SealedUsizeInst
+  : core_slice_index_private_slice_index_Sealed usize = ()
+
+// Trait implementation: [core::slice::index::usize]
+let core_slice_index_SliceIndexUsizeSliceTInst (t : Type0) :
+  core_slice_index_SliceIndex usize (slice t) = {
+  sealedInst = core_slice_index_private_slice_index_SealedUsizeInst;
+  output = t;
+  get = core_slice_index_usize_get t;
+  get_mut = core_slice_index_usize_get_mut t;
+  get_mut_back = core_slice_index_usize_get_mut_back t;
+  get_unchecked = core_slice_index_usize_get_unchecked t;
+  get_unchecked_mut = core_slice_index_usize_get_unchecked_mut t;
+  index = core_slice_index_usize_index t;
+  index_mut = core_slice_index_usize_index_mut t;
+  index_mut_back = core_slice_index_usize_index_mut_back t;
+}
+
+// [alloc::vec::Vec::index]: forward function
+let alloc_vec_Vec_index (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (self : alloc_vec_Vec t) (i : idx) : result inst.output =
+  admit () // TODO
+
+// [alloc::vec::Vec::index_mut]: forward function
+let alloc_vec_Vec_index_mut (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (self : alloc_vec_Vec t) (i : idx) : result inst.output =
+  admit () // TODO
+
+// [alloc::vec::Vec::index_mut]: backward function 0
+let alloc_vec_Vec_index_mut_back
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (self : alloc_vec_Vec t) (i : idx) (x : inst.output) : result (alloc_vec_Vec t) =
+  admit () // TODO
+
+// Trait implementation: [alloc::vec::Vec]
+let alloc_vec_Vec_coreopsindexIndexInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_Index (alloc_vec_Vec t) idx = {
+  output = inst.output;
+  index = alloc_vec_Vec_index t idx inst;
+}
+
+// Trait implementation: [alloc::vec::Vec]
+let alloc_vec_Vec_coreopsindexIndexMutInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_IndexMut (alloc_vec_Vec t) idx = {
+  indexInst = alloc_vec_Vec_coreopsindexIndexInst t idx inst;
+  index_mut = alloc_vec_Vec_index_mut t idx inst;
+  index_mut_back = alloc_vec_Vec_index_mut_back t idx inst;
+}
+
+(*** Theorems *)
+
+let alloc_vec_Vec_index_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
+  Lemma (
+    alloc_vec_Vec_index a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i ==
+      alloc_vec_Vec_index_usize v i)
+  [SMTPat (alloc_vec_Vec_index a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i)]
+  =
+  admit()
+
+let alloc_vec_Vec_index_mut_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
+  Lemma (
+    alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i ==
+      alloc_vec_Vec_index_usize v i)
+  [SMTPat (alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i)]
+  =
+  admit()
+
+let alloc_vec_Vec_index_mut_back_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) :
+  Lemma (
+    alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x ==
+      alloc_vec_Vec_update_usize v i x)
+  [SMTPat (alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x)]
+  =
+  admit()
diff --git a/tests/fstar-split/hashmap_on_disk/HashmapMain.Clauses.Template.fst b/tests/fstar-split/hashmap_on_disk/HashmapMain.Clauses.Template.fst
new file mode 100644
index 00000000..7b274f59
--- /dev/null
+++ b/tests/fstar-split/hashmap_on_disk/HashmapMain.Clauses.Template.fst
@@ -0,0 +1,72 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [hashmap_main]: templates for the decreases clauses *)
+module HashmapMain.Clauses.Template
+open Primitives
+open HashmapMain.Types
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::allocate_slots]: decreases clause
+    Source: 'src/hashmap.rs', lines 50:4-56:5 *)
+unfold
+let hashmap_HashMap_allocate_slots_loop_decreases (t : Type0)
+  (slots : alloc_vec_Vec (hashmap_List_t t)) (n : usize) : nat =
+  admit ()
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::clear]: decreases clause
+    Source: 'src/hashmap.rs', lines 80:4-88:5 *)
+unfold
+let hashmap_HashMap_clear_loop_decreases (t : Type0)
+  (slots : alloc_vec_Vec (hashmap_List_t t)) (i : usize) : nat =
+  admit ()
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::insert_in_list]: decreases clause
+    Source: 'src/hashmap.rs', lines 97:4-114:5 *)
+unfold
+let hashmap_HashMap_insert_in_list_loop_decreases (t : Type0) (key : usize)
+  (value : t) (ls : hashmap_List_t t) : nat =
+  admit ()
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::move_elements_from_list]: decreases clause
+    Source: 'src/hashmap.rs', lines 183:4-196:5 *)
+unfold
+let hashmap_HashMap_move_elements_from_list_loop_decreases (t : Type0)
+  (ntable : hashmap_HashMap_t t) (ls : hashmap_List_t t) : nat =
+  admit ()
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::move_elements]: decreases clause
+    Source: 'src/hashmap.rs', lines 171:4-180:5 *)
+unfold
+let hashmap_HashMap_move_elements_loop_decreases (t : Type0)
+  (ntable : hashmap_HashMap_t t) (slots : alloc_vec_Vec (hashmap_List_t t))
+  (i : usize) : nat =
+  admit ()
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::contains_key_in_list]: decreases clause
+    Source: 'src/hashmap.rs', lines 206:4-219:5 *)
+unfold
+let hashmap_HashMap_contains_key_in_list_loop_decreases (t : Type0)
+  (key : usize) (ls : hashmap_List_t t) : nat =
+  admit ()
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_in_list]: decreases clause
+    Source: 'src/hashmap.rs', lines 224:4-237:5 *)
+unfold
+let hashmap_HashMap_get_in_list_loop_decreases (t : Type0) (key : usize)
+  (ls : hashmap_List_t t) : nat =
+  admit ()
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_mut_in_list]: decreases clause
+    Source: 'src/hashmap.rs', lines 245:4-254:5 *)
+unfold
+let hashmap_HashMap_get_mut_in_list_loop_decreases (t : Type0)
+  (ls : hashmap_List_t t) (key : usize) : nat =
+  admit ()
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::remove_from_list]: decreases clause
+    Source: 'src/hashmap.rs', lines 265:4-291:5 *)
+unfold
+let hashmap_HashMap_remove_from_list_loop_decreases (t : Type0) (key : usize)
+  (ls : hashmap_List_t t) : nat =
+  admit ()
+
diff --git a/tests/fstar-split/hashmap_on_disk/HashmapMain.Clauses.fst b/tests/fstar-split/hashmap_on_disk/HashmapMain.Clauses.fst
new file mode 100644
index 00000000..be5a4ab1
--- /dev/null
+++ b/tests/fstar-split/hashmap_on_disk/HashmapMain.Clauses.fst
@@ -0,0 +1,61 @@
+(** [hashmap]: the decreases clauses *)
+module HashmapMain.Clauses
+open Primitives
+open FStar.List.Tot
+open HashmapMain.Types
+
+#set-options "--z3rlimit 50 --fuel 0 --ifuel 1"
+
+(** [hashmap::HashMap::allocate_slots]: decreases clause *)
+unfold
+let hashmap_HashMap_allocate_slots_loop_decreases (t : Type0) (slots : alloc_vec_Vec (hashmap_List_t t))
+  (n : usize) : nat = n
+
+(** [hashmap::HashMap::clear]: decreases clause *)
+unfold
+let hashmap_HashMap_clear_loop_decreases (t : Type0) (slots : alloc_vec_Vec (hashmap_List_t t))
+  (i : usize) : nat =
+  if i < length slots then length slots - i else 0
+
+(** [hashmap::HashMap::insert_in_list]: decreases clause *)
+unfold
+let hashmap_HashMap_insert_in_list_loop_decreases (t : Type0) (key : usize) (value : t)
+  (ls : hashmap_List_t t) : hashmap_List_t t =
+  ls
+
+(** [hashmap::HashMap::move_elements_from_list]: decreases clause *)
+unfold
+let hashmap_HashMap_move_elements_from_list_loop_decreases (t : Type0)
+  (ntable : hashmap_HashMap_t t) (ls : hashmap_List_t t) : hashmap_List_t t =
+  ls
+
+(** [hashmap::HashMap::move_elements]: decreases clause *)
+unfold
+let hashmap_HashMap_move_elements_loop_decreases (t : Type0) (ntable : hashmap_HashMap_t t)
+  (slots : alloc_vec_Vec (hashmap_List_t t)) (i : usize) : nat =
+  if i < length slots then length slots - i else 0
+
+(** [hashmap::HashMap::contains_key_in_list]: decreases clause *)
+unfold
+let hashmap_HashMap_contains_key_in_list_loop_decreases (t : Type0) (key : usize)
+  (ls : hashmap_List_t t) : hashmap_List_t t =
+  ls
+
+(** [hashmap::HashMap::get_in_list]: decreases clause *)
+unfold
+let hashmap_HashMap_get_in_list_loop_decreases (t : Type0) (key : usize) (ls : hashmap_List_t t) :
+  hashmap_List_t t =
+  ls
+
+(** [hashmap::HashMap::get_mut_in_list]: decreases clause *)
+unfold
+let hashmap_HashMap_get_mut_in_list_loop_decreases (t : Type0)
+  (ls : hashmap_List_t t) (key : usize) : hashmap_List_t t =
+  ls
+
+(** [hashmap::HashMap::remove_from_list]: decreases clause *)
+unfold
+let hashmap_HashMap_remove_from_list_loop_decreases (t : Type0) (key : usize)
+  (ls : hashmap_List_t t) : hashmap_List_t t =
+  ls
+
diff --git a/tests/fstar-split/hashmap_on_disk/HashmapMain.Funs.fst b/tests/fstar-split/hashmap_on_disk/HashmapMain.Funs.fst
new file mode 100644
index 00000000..b2800e1e
--- /dev/null
+++ b/tests/fstar-split/hashmap_on_disk/HashmapMain.Funs.fst
@@ -0,0 +1,576 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [hashmap_main]: function definitions *)
+module HashmapMain.Funs
+open Primitives
+include HashmapMain.Types
+include HashmapMain.FunsExternal
+include HashmapMain.Clauses
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [hashmap_main::hashmap::hash_key]: forward function
+    Source: 'src/hashmap.rs', lines 27:0-27:32 *)
+let hashmap_hash_key (k : usize) : result usize =
+  Return k
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::allocate_slots]: loop 0: forward function
+    Source: 'src/hashmap.rs', lines 50:4-56:5 *)
+let rec hashmap_HashMap_allocate_slots_loop
+  (t : Type0) (slots : alloc_vec_Vec (hashmap_List_t t)) (n : usize) :
+  Tot (result (alloc_vec_Vec (hashmap_List_t t)))
+  (decreases (hashmap_HashMap_allocate_slots_loop_decreases t slots n))
+  =
+  if n > 0
+  then
+    let* slots1 = alloc_vec_Vec_push (hashmap_List_t t) slots Hashmap_List_Nil
+      in
+    let* n1 = usize_sub n 1 in
+    hashmap_HashMap_allocate_slots_loop t slots1 n1
+  else Return slots
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::allocate_slots]: forward function
+    Source: 'src/hashmap.rs', lines 50:4-50:76 *)
+let hashmap_HashMap_allocate_slots
+  (t : Type0) (slots : alloc_vec_Vec (hashmap_List_t t)) (n : usize) :
+  result (alloc_vec_Vec (hashmap_List_t t))
+  =
+  hashmap_HashMap_allocate_slots_loop t slots n
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::new_with_capacity]: forward function
+    Source: 'src/hashmap.rs', lines 59:4-63:13 *)
+let hashmap_HashMap_new_with_capacity
+  (t : Type0) (capacity : usize) (max_load_dividend : usize)
+  (max_load_divisor : usize) :
+  result (hashmap_HashMap_t t)
+  =
+  let v = alloc_vec_Vec_new (hashmap_List_t t) in
+  let* slots = hashmap_HashMap_allocate_slots t v capacity in
+  let* i = usize_mul capacity max_load_dividend in
+  let* i1 = usize_div i max_load_divisor in
+  Return
+    {
+      num_entries = 0;
+      max_load_factor = (max_load_dividend, max_load_divisor);
+      max_load = i1;
+      slots = slots
+    }
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::new]: forward function
+    Source: 'src/hashmap.rs', lines 75:4-75:24 *)
+let hashmap_HashMap_new (t : Type0) : result (hashmap_HashMap_t t) =
+  hashmap_HashMap_new_with_capacity t 32 4 5
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::clear]: loop 0: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/hashmap.rs', lines 80:4-88:5 *)
+let rec hashmap_HashMap_clear_loop
+  (t : Type0) (slots : alloc_vec_Vec (hashmap_List_t t)) (i : usize) :
+  Tot (result (alloc_vec_Vec (hashmap_List_t t)))
+  (decreases (hashmap_HashMap_clear_loop_decreases t slots i))
+  =
+  let i1 = alloc_vec_Vec_len (hashmap_List_t t) slots in
+  if i < i1
+  then
+    let* i2 = usize_add i 1 in
+    let* slots1 =
+      alloc_vec_Vec_index_mut_back (hashmap_List_t t) usize
+        (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t)) slots i
+        Hashmap_List_Nil in
+    hashmap_HashMap_clear_loop t slots1 i2
+  else Return slots
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::clear]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/hashmap.rs', lines 80:4-80:27 *)
+let hashmap_HashMap_clear
+  (t : Type0) (self : hashmap_HashMap_t t) : result (hashmap_HashMap_t t) =
+  let* v = hashmap_HashMap_clear_loop t self.slots 0 in
+  Return { self with num_entries = 0; slots = v }
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::len]: forward function
+    Source: 'src/hashmap.rs', lines 90:4-90:30 *)
+let hashmap_HashMap_len
+  (t : Type0) (self : hashmap_HashMap_t t) : result usize =
+  Return self.num_entries
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::insert_in_list]: loop 0: forward function
+    Source: 'src/hashmap.rs', lines 97:4-114:5 *)
+let rec hashmap_HashMap_insert_in_list_loop
+  (t : Type0) (key : usize) (value : t) (ls : hashmap_List_t t) :
+  Tot (result bool)
+  (decreases (hashmap_HashMap_insert_in_list_loop_decreases t key value ls))
+  =
+  begin match ls with
+  | Hashmap_List_Cons ckey _ tl ->
+    if ckey = key
+    then Return false
+    else hashmap_HashMap_insert_in_list_loop t key value tl
+  | Hashmap_List_Nil -> Return true
+  end
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::insert_in_list]: forward function
+    Source: 'src/hashmap.rs', lines 97:4-97:71 *)
+let hashmap_HashMap_insert_in_list
+  (t : Type0) (key : usize) (value : t) (ls : hashmap_List_t t) : result bool =
+  hashmap_HashMap_insert_in_list_loop t key value ls
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::insert_in_list]: loop 0: backward function 0
+    Source: 'src/hashmap.rs', lines 97:4-114:5 *)
+let rec hashmap_HashMap_insert_in_list_loop_back
+  (t : Type0) (key : usize) (value : t) (ls : hashmap_List_t t) :
+  Tot (result (hashmap_List_t t))
+  (decreases (hashmap_HashMap_insert_in_list_loop_decreases t key value ls))
+  =
+  begin match ls with
+  | Hashmap_List_Cons ckey cvalue tl ->
+    if ckey = key
+    then Return (Hashmap_List_Cons ckey value tl)
+    else
+      let* tl1 = hashmap_HashMap_insert_in_list_loop_back t key value tl in
+      Return (Hashmap_List_Cons ckey cvalue tl1)
+  | Hashmap_List_Nil ->
+    let l = Hashmap_List_Nil in Return (Hashmap_List_Cons key value l)
+  end
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::insert_in_list]: backward function 0
+    Source: 'src/hashmap.rs', lines 97:4-97:71 *)
+let hashmap_HashMap_insert_in_list_back
+  (t : Type0) (key : usize) (value : t) (ls : hashmap_List_t t) :
+  result (hashmap_List_t t)
+  =
+  hashmap_HashMap_insert_in_list_loop_back t key value ls
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::insert_no_resize]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/hashmap.rs', lines 117:4-117:54 *)
+let hashmap_HashMap_insert_no_resize
+  (t : Type0) (self : hashmap_HashMap_t t) (key : usize) (value : t) :
+  result (hashmap_HashMap_t t)
+  =
+  let* hash = hashmap_hash_key key in
+  let i = alloc_vec_Vec_len (hashmap_List_t t) self.slots in
+  let* hash_mod = usize_rem hash i in
+  let* l =
+    alloc_vec_Vec_index_mut (hashmap_List_t t) usize
+      (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
+      self.slots hash_mod in
+  let* inserted = hashmap_HashMap_insert_in_list t key value l in
+  if inserted
+  then
+    let* i1 = usize_add self.num_entries 1 in
+    let* l1 = hashmap_HashMap_insert_in_list_back t key value l in
+    let* v =
+      alloc_vec_Vec_index_mut_back (hashmap_List_t t) usize
+        (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
+        self.slots hash_mod l1 in
+    Return { self with num_entries = i1; slots = v }
+  else
+    let* l1 = hashmap_HashMap_insert_in_list_back t key value l in
+    let* v =
+      alloc_vec_Vec_index_mut_back (hashmap_List_t t) usize
+        (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
+        self.slots hash_mod l1 in
+    Return { self with slots = v }
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::move_elements_from_list]: loop 0: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/hashmap.rs', lines 183:4-196:5 *)
+let rec hashmap_HashMap_move_elements_from_list_loop
+  (t : Type0) (ntable : hashmap_HashMap_t t) (ls : hashmap_List_t t) :
+  Tot (result (hashmap_HashMap_t t))
+  (decreases (
+    hashmap_HashMap_move_elements_from_list_loop_decreases t ntable ls))
+  =
+  begin match ls with
+  | Hashmap_List_Cons k v tl ->
+    let* ntable1 = hashmap_HashMap_insert_no_resize t ntable k v in
+    hashmap_HashMap_move_elements_from_list_loop t ntable1 tl
+  | Hashmap_List_Nil -> Return ntable
+  end
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::move_elements_from_list]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/hashmap.rs', lines 183:4-183:72 *)
+let hashmap_HashMap_move_elements_from_list
+  (t : Type0) (ntable : hashmap_HashMap_t t) (ls : hashmap_List_t t) :
+  result (hashmap_HashMap_t t)
+  =
+  hashmap_HashMap_move_elements_from_list_loop t ntable ls
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::move_elements]: loop 0: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/hashmap.rs', lines 171:4-180:5 *)
+let rec hashmap_HashMap_move_elements_loop
+  (t : Type0) (ntable : hashmap_HashMap_t t)
+  (slots : alloc_vec_Vec (hashmap_List_t t)) (i : usize) :
+  Tot (result ((hashmap_HashMap_t t) & (alloc_vec_Vec (hashmap_List_t t))))
+  (decreases (hashmap_HashMap_move_elements_loop_decreases t ntable slots i))
+  =
+  let i1 = alloc_vec_Vec_len (hashmap_List_t t) slots in
+  if i < i1
+  then
+    let* l =
+      alloc_vec_Vec_index_mut (hashmap_List_t t) usize
+        (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t)) slots i
+      in
+    let ls = core_mem_replace (hashmap_List_t t) l Hashmap_List_Nil in
+    let* ntable1 = hashmap_HashMap_move_elements_from_list t ntable ls in
+    let* i2 = usize_add i 1 in
+    let l1 = core_mem_replace_back (hashmap_List_t t) l Hashmap_List_Nil in
+    let* slots1 =
+      alloc_vec_Vec_index_mut_back (hashmap_List_t t) usize
+        (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t)) slots i
+        l1 in
+    hashmap_HashMap_move_elements_loop t ntable1 slots1 i2
+  else Return (ntable, slots)
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::move_elements]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/hashmap.rs', lines 171:4-171:95 *)
+let hashmap_HashMap_move_elements
+  (t : Type0) (ntable : hashmap_HashMap_t t)
+  (slots : alloc_vec_Vec (hashmap_List_t t)) (i : usize) :
+  result ((hashmap_HashMap_t t) & (alloc_vec_Vec (hashmap_List_t t)))
+  =
+  hashmap_HashMap_move_elements_loop t ntable slots i
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::try_resize]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/hashmap.rs', lines 140:4-140:28 *)
+let hashmap_HashMap_try_resize
+  (t : Type0) (self : hashmap_HashMap_t t) : result (hashmap_HashMap_t t) =
+  let* max_usize = scalar_cast U32 Usize core_u32_max in
+  let capacity = alloc_vec_Vec_len (hashmap_List_t t) self.slots in
+  let* n1 = usize_div max_usize 2 in
+  let (i, i1) = self.max_load_factor in
+  let* i2 = usize_div n1 i in
+  if capacity <= i2
+  then
+    let* i3 = usize_mul capacity 2 in
+    let* ntable = hashmap_HashMap_new_with_capacity t i3 i i1 in
+    let* (ntable1, _) = hashmap_HashMap_move_elements t ntable self.slots 0 in
+    Return
+      { ntable1 with num_entries = self.num_entries; max_load_factor = (i, i1)
+      }
+  else Return { self with max_load_factor = (i, i1) }
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::insert]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/hashmap.rs', lines 129:4-129:48 *)
+let hashmap_HashMap_insert
+  (t : Type0) (self : hashmap_HashMap_t t) (key : usize) (value : t) :
+  result (hashmap_HashMap_t t)
+  =
+  let* self1 = hashmap_HashMap_insert_no_resize t self key value in
+  let* i = hashmap_HashMap_len t self1 in
+  if i > self1.max_load
+  then hashmap_HashMap_try_resize t self1
+  else Return self1
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::contains_key_in_list]: loop 0: forward function
+    Source: 'src/hashmap.rs', lines 206:4-219:5 *)
+let rec hashmap_HashMap_contains_key_in_list_loop
+  (t : Type0) (key : usize) (ls : hashmap_List_t t) :
+  Tot (result bool)
+  (decreases (hashmap_HashMap_contains_key_in_list_loop_decreases t key ls))
+  =
+  begin match ls with
+  | Hashmap_List_Cons ckey _ tl ->
+    if ckey = key
+    then Return true
+    else hashmap_HashMap_contains_key_in_list_loop t key tl
+  | Hashmap_List_Nil -> Return false
+  end
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::contains_key_in_list]: forward function
+    Source: 'src/hashmap.rs', lines 206:4-206:68 *)
+let hashmap_HashMap_contains_key_in_list
+  (t : Type0) (key : usize) (ls : hashmap_List_t t) : result bool =
+  hashmap_HashMap_contains_key_in_list_loop t key ls
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::contains_key]: forward function
+    Source: 'src/hashmap.rs', lines 199:4-199:49 *)
+let hashmap_HashMap_contains_key
+  (t : Type0) (self : hashmap_HashMap_t t) (key : usize) : result bool =
+  let* hash = hashmap_hash_key key in
+  let i = alloc_vec_Vec_len (hashmap_List_t t) self.slots in
+  let* hash_mod = usize_rem hash i in
+  let* l =
+    alloc_vec_Vec_index (hashmap_List_t t) usize
+      (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
+      self.slots hash_mod in
+  hashmap_HashMap_contains_key_in_list t key l
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_in_list]: loop 0: forward function
+    Source: 'src/hashmap.rs', lines 224:4-237:5 *)
+let rec hashmap_HashMap_get_in_list_loop
+  (t : Type0) (key : usize) (ls : hashmap_List_t t) :
+  Tot (result t)
+  (decreases (hashmap_HashMap_get_in_list_loop_decreases t key ls))
+  =
+  begin match ls with
+  | Hashmap_List_Cons ckey cvalue tl ->
+    if ckey = key
+    then Return cvalue
+    else hashmap_HashMap_get_in_list_loop t key tl
+  | Hashmap_List_Nil -> Fail Failure
+  end
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_in_list]: forward function
+    Source: 'src/hashmap.rs', lines 224:4-224:70 *)
+let hashmap_HashMap_get_in_list
+  (t : Type0) (key : usize) (ls : hashmap_List_t t) : result t =
+  hashmap_HashMap_get_in_list_loop t key ls
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get]: forward function
+    Source: 'src/hashmap.rs', lines 239:4-239:55 *)
+let hashmap_HashMap_get
+  (t : Type0) (self : hashmap_HashMap_t t) (key : usize) : result t =
+  let* hash = hashmap_hash_key key in
+  let i = alloc_vec_Vec_len (hashmap_List_t t) self.slots in
+  let* hash_mod = usize_rem hash i in
+  let* l =
+    alloc_vec_Vec_index (hashmap_List_t t) usize
+      (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
+      self.slots hash_mod in
+  hashmap_HashMap_get_in_list t key l
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_mut_in_list]: loop 0: forward function
+    Source: 'src/hashmap.rs', lines 245:4-254:5 *)
+let rec hashmap_HashMap_get_mut_in_list_loop
+  (t : Type0) (ls : hashmap_List_t t) (key : usize) :
+  Tot (result t)
+  (decreases (hashmap_HashMap_get_mut_in_list_loop_decreases t ls key))
+  =
+  begin match ls with
+  | Hashmap_List_Cons ckey cvalue tl ->
+    if ckey = key
+    then Return cvalue
+    else hashmap_HashMap_get_mut_in_list_loop t tl key
+  | Hashmap_List_Nil -> Fail Failure
+  end
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_mut_in_list]: forward function
+    Source: 'src/hashmap.rs', lines 245:4-245:86 *)
+let hashmap_HashMap_get_mut_in_list
+  (t : Type0) (ls : hashmap_List_t t) (key : usize) : result t =
+  hashmap_HashMap_get_mut_in_list_loop t ls key
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_mut_in_list]: loop 0: backward function 0
+    Source: 'src/hashmap.rs', lines 245:4-254:5 *)
+let rec hashmap_HashMap_get_mut_in_list_loop_back
+  (t : Type0) (ls : hashmap_List_t t) (key : usize) (ret : t) :
+  Tot (result (hashmap_List_t t))
+  (decreases (hashmap_HashMap_get_mut_in_list_loop_decreases t ls key))
+  =
+  begin match ls with
+  | Hashmap_List_Cons ckey cvalue tl ->
+    if ckey = key
+    then Return (Hashmap_List_Cons ckey ret tl)
+    else
+      let* tl1 = hashmap_HashMap_get_mut_in_list_loop_back t tl key ret in
+      Return (Hashmap_List_Cons ckey cvalue tl1)
+  | Hashmap_List_Nil -> Fail Failure
+  end
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_mut_in_list]: backward function 0
+    Source: 'src/hashmap.rs', lines 245:4-245:86 *)
+let hashmap_HashMap_get_mut_in_list_back
+  (t : Type0) (ls : hashmap_List_t t) (key : usize) (ret : t) :
+  result (hashmap_List_t t)
+  =
+  hashmap_HashMap_get_mut_in_list_loop_back t ls key ret
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_mut]: forward function
+    Source: 'src/hashmap.rs', lines 257:4-257:67 *)
+let hashmap_HashMap_get_mut
+  (t : Type0) (self : hashmap_HashMap_t t) (key : usize) : result t =
+  let* hash = hashmap_hash_key key in
+  let i = alloc_vec_Vec_len (hashmap_List_t t) self.slots in
+  let* hash_mod = usize_rem hash i in
+  let* l =
+    alloc_vec_Vec_index_mut (hashmap_List_t t) usize
+      (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
+      self.slots hash_mod in
+  hashmap_HashMap_get_mut_in_list t l key
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_mut]: backward function 0
+    Source: 'src/hashmap.rs', lines 257:4-257:67 *)
+let hashmap_HashMap_get_mut_back
+  (t : Type0) (self : hashmap_HashMap_t t) (key : usize) (ret : t) :
+  result (hashmap_HashMap_t t)
+  =
+  let* hash = hashmap_hash_key key in
+  let i = alloc_vec_Vec_len (hashmap_List_t t) self.slots in
+  let* hash_mod = usize_rem hash i in
+  let* l =
+    alloc_vec_Vec_index_mut (hashmap_List_t t) usize
+      (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
+      self.slots hash_mod in
+  let* l1 = hashmap_HashMap_get_mut_in_list_back t l key ret in
+  let* v =
+    alloc_vec_Vec_index_mut_back (hashmap_List_t t) usize
+      (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
+      self.slots hash_mod l1 in
+  Return { self with slots = v }
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::remove_from_list]: loop 0: forward function
+    Source: 'src/hashmap.rs', lines 265:4-291:5 *)
+let rec hashmap_HashMap_remove_from_list_loop
+  (t : Type0) (key : usize) (ls : hashmap_List_t t) :
+  Tot (result (option t))
+  (decreases (hashmap_HashMap_remove_from_list_loop_decreases t key ls))
+  =
+  begin match ls with
+  | Hashmap_List_Cons ckey x tl ->
+    if ckey = key
+    then
+      let mv_ls =
+        core_mem_replace (hashmap_List_t t) (Hashmap_List_Cons ckey x tl)
+          Hashmap_List_Nil in
+      begin match mv_ls with
+      | Hashmap_List_Cons _ cvalue _ -> Return (Some cvalue)
+      | Hashmap_List_Nil -> Fail Failure
+      end
+    else hashmap_HashMap_remove_from_list_loop t key tl
+  | Hashmap_List_Nil -> Return None
+  end
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::remove_from_list]: forward function
+    Source: 'src/hashmap.rs', lines 265:4-265:69 *)
+let hashmap_HashMap_remove_from_list
+  (t : Type0) (key : usize) (ls : hashmap_List_t t) : result (option t) =
+  hashmap_HashMap_remove_from_list_loop t key ls
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::remove_from_list]: loop 0: backward function 1
+    Source: 'src/hashmap.rs', lines 265:4-291:5 *)
+let rec hashmap_HashMap_remove_from_list_loop_back
+  (t : Type0) (key : usize) (ls : hashmap_List_t t) :
+  Tot (result (hashmap_List_t t))
+  (decreases (hashmap_HashMap_remove_from_list_loop_decreases t key ls))
+  =
+  begin match ls with
+  | Hashmap_List_Cons ckey x tl ->
+    if ckey = key
+    then
+      let mv_ls =
+        core_mem_replace (hashmap_List_t t) (Hashmap_List_Cons ckey x tl)
+          Hashmap_List_Nil in
+      begin match mv_ls with
+      | Hashmap_List_Cons _ _ tl1 -> Return tl1
+      | Hashmap_List_Nil -> Fail Failure
+      end
+    else
+      let* tl1 = hashmap_HashMap_remove_from_list_loop_back t key tl in
+      Return (Hashmap_List_Cons ckey x tl1)
+  | Hashmap_List_Nil -> Return Hashmap_List_Nil
+  end
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::remove_from_list]: backward function 1
+    Source: 'src/hashmap.rs', lines 265:4-265:69 *)
+let hashmap_HashMap_remove_from_list_back
+  (t : Type0) (key : usize) (ls : hashmap_List_t t) :
+  result (hashmap_List_t t)
+  =
+  hashmap_HashMap_remove_from_list_loop_back t key ls
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::remove]: forward function
+    Source: 'src/hashmap.rs', lines 294:4-294:52 *)
+let hashmap_HashMap_remove
+  (t : Type0) (self : hashmap_HashMap_t t) (key : usize) : result (option t) =
+  let* hash = hashmap_hash_key key in
+  let i = alloc_vec_Vec_len (hashmap_List_t t) self.slots in
+  let* hash_mod = usize_rem hash i in
+  let* l =
+    alloc_vec_Vec_index_mut (hashmap_List_t t) usize
+      (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
+      self.slots hash_mod in
+  let* x = hashmap_HashMap_remove_from_list t key l in
+  begin match x with
+  | None -> Return None
+  | Some x1 -> let* _ = usize_sub self.num_entries 1 in Return (Some x1)
+  end
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::remove]: backward function 0
+    Source: 'src/hashmap.rs', lines 294:4-294:52 *)
+let hashmap_HashMap_remove_back
+  (t : Type0) (self : hashmap_HashMap_t t) (key : usize) :
+  result (hashmap_HashMap_t t)
+  =
+  let* hash = hashmap_hash_key key in
+  let i = alloc_vec_Vec_len (hashmap_List_t t) self.slots in
+  let* hash_mod = usize_rem hash i in
+  let* l =
+    alloc_vec_Vec_index_mut (hashmap_List_t t) usize
+      (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
+      self.slots hash_mod in
+  let* x = hashmap_HashMap_remove_from_list t key l in
+  begin match x with
+  | None ->
+    let* l1 = hashmap_HashMap_remove_from_list_back t key l in
+    let* v =
+      alloc_vec_Vec_index_mut_back (hashmap_List_t t) usize
+        (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
+        self.slots hash_mod l1 in
+    Return { self with slots = v }
+  | Some _ ->
+    let* i1 = usize_sub self.num_entries 1 in
+    let* l1 = hashmap_HashMap_remove_from_list_back t key l in
+    let* v =
+      alloc_vec_Vec_index_mut_back (hashmap_List_t t) usize
+        (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
+        self.slots hash_mod l1 in
+    Return { self with num_entries = i1; slots = v }
+  end
+
+(** [hashmap_main::hashmap::test1]: forward function
+    Source: 'src/hashmap.rs', lines 315:0-315:10 *)
+let hashmap_test1 : result unit =
+  let* hm = hashmap_HashMap_new u64 in
+  let* hm1 = hashmap_HashMap_insert u64 hm 0 42 in
+  let* hm2 = hashmap_HashMap_insert u64 hm1 128 18 in
+  let* hm3 = hashmap_HashMap_insert u64 hm2 1024 138 in
+  let* hm4 = hashmap_HashMap_insert u64 hm3 1056 256 in
+  let* i = hashmap_HashMap_get u64 hm4 128 in
+  if not (i = 18)
+  then Fail Failure
+  else
+    let* hm5 = hashmap_HashMap_get_mut_back u64 hm4 1024 56 in
+    let* i1 = hashmap_HashMap_get u64 hm5 1024 in
+    if not (i1 = 56)
+    then Fail Failure
+    else
+      let* x = hashmap_HashMap_remove u64 hm5 1024 in
+      begin match x with
+      | None -> Fail Failure
+      | Some x1 ->
+        if not (x1 = 56)
+        then Fail Failure
+        else
+          let* hm6 = hashmap_HashMap_remove_back u64 hm5 1024 in
+          let* i2 = hashmap_HashMap_get u64 hm6 0 in
+          if not (i2 = 42)
+          then Fail Failure
+          else
+            let* i3 = hashmap_HashMap_get u64 hm6 128 in
+            if not (i3 = 18)
+            then Fail Failure
+            else
+              let* i4 = hashmap_HashMap_get u64 hm6 1056 in
+              if not (i4 = 256) then Fail Failure else Return ()
+      end
+
+(** [hashmap_main::insert_on_disk]: forward function
+    Source: 'src/hashmap_main.rs', lines 7:0-7:43 *)
+let insert_on_disk
+  (key : usize) (value : u64) (st : state) : result (state & unit) =
+  let* (st1, hm) = hashmap_utils_deserialize st in
+  let* hm1 = hashmap_HashMap_insert u64 hm key value in
+  let* (st2, _) = hashmap_utils_serialize hm1 st1 in
+  Return (st2, ())
+
+(** [hashmap_main::main]: forward function
+    Source: 'src/hashmap_main.rs', lines 16:0-16:13 *)
+let main : result unit =
+  Return ()
+
diff --git a/tests/fstar-split/hashmap_on_disk/HashmapMain.FunsExternal.fsti b/tests/fstar-split/hashmap_on_disk/HashmapMain.FunsExternal.fsti
new file mode 100644
index 00000000..b00bbcde
--- /dev/null
+++ b/tests/fstar-split/hashmap_on_disk/HashmapMain.FunsExternal.fsti
@@ -0,0 +1,18 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [hashmap_main]: external function declarations *)
+module HashmapMain.FunsExternal
+open Primitives
+include HashmapMain.Types
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [hashmap_main::hashmap_utils::deserialize]: forward function
+    Source: 'src/hashmap_utils.rs', lines 10:0-10:43 *)
+val hashmap_utils_deserialize
+  : state -> result (state & (hashmap_HashMap_t u64))
+
+(** [hashmap_main::hashmap_utils::serialize]: forward function
+    Source: 'src/hashmap_utils.rs', lines 5:0-5:42 *)
+val hashmap_utils_serialize
+  : hashmap_HashMap_t u64 -> state -> result (state & unit)
+
diff --git a/tests/fstar-split/hashmap_on_disk/HashmapMain.Properties.fst b/tests/fstar-split/hashmap_on_disk/HashmapMain.Properties.fst
new file mode 100644
index 00000000..358df29e
--- /dev/null
+++ b/tests/fstar-split/hashmap_on_disk/HashmapMain.Properties.fst
@@ -0,0 +1,48 @@
+(** Properties about the hashmap written on disk *)
+module HashmapMain.Properties
+open Primitives
+open HashmapMain.Funs
+
+#set-options "--z3rlimit 50 --fuel 0 --ifuel 1"
+
+/// Below, we focus on the functions to read from disk/write to disk to showcase
+/// how such reasoning which mixes opaque functions together with a state-error
+/// monad can be performed.
+
+(*** Hypotheses *)
+
+/// [state_v] gives us the hash map currently stored on disk
+assume
+val state_v : state -> hashmap_HashMap_t u64
+
+/// [serialize] updates the hash map stored on disk
+assume
+val serialize_lem (hm : hashmap_HashMap_t u64) (st : state) : Lemma (
+  match hashmap_utils_serialize hm st with
+  | Fail _ -> True
+  | Return (st', ()) -> state_v st' == hm)
+  [SMTPat (hashmap_utils_serialize hm st)]
+
+/// [deserialize] gives us the hash map stored on disk, without updating it
+assume
+val deserialize_lem (st : state) : Lemma (
+  match hashmap_utils_deserialize st with
+  | Fail _ -> True
+  | Return (st', hm) -> hm == state_v st /\ st' == st)
+  [SMTPat (hashmap_utils_deserialize st)]
+
+(*** Lemmas *)
+
+/// The obvious lemma about [insert_on_disk]: the updated hash map stored on disk
+/// is exactly the hash map produced from inserting the binding ([key], [value])
+/// in the hash map previously stored on disk.
+val insert_on_disk_lem (key : usize) (value : u64) (st : state) : Lemma (
+  match insert_on_disk key value st with
+  | Fail _ -> True
+  | Return (st', ()) ->
+    let hm = state_v st in
+    match hashmap_HashMap_insert u64 hm key value with
+    | Fail _ -> False
+    | Return hm' -> hm' == state_v st')
+
+let insert_on_disk_lem key value st = ()
diff --git a/tests/fstar-split/hashmap_on_disk/HashmapMain.Types.fst b/tests/fstar-split/hashmap_on_disk/HashmapMain.Types.fst
new file mode 100644
index 00000000..afebcde3
--- /dev/null
+++ b/tests/fstar-split/hashmap_on_disk/HashmapMain.Types.fst
@@ -0,0 +1,24 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [hashmap_main]: type definitions *)
+module HashmapMain.Types
+open Primitives
+include HashmapMain.TypesExternal
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [hashmap_main::hashmap::List]
+    Source: 'src/hashmap.rs', lines 19:0-19:16 *)
+type hashmap_List_t (t : Type0) =
+| Hashmap_List_Cons : usize -> t -> hashmap_List_t t -> hashmap_List_t t
+| Hashmap_List_Nil : hashmap_List_t t
+
+(** [hashmap_main::hashmap::HashMap]
+    Source: 'src/hashmap.rs', lines 35:0-35:21 *)
+type hashmap_HashMap_t (t : Type0) =
+{
+  num_entries : usize;
+  max_load_factor : (usize & usize);
+  max_load : usize;
+  slots : alloc_vec_Vec (hashmap_List_t t);
+}
+
diff --git a/tests/fstar-split/hashmap_on_disk/HashmapMain.TypesExternal.fsti b/tests/fstar-split/hashmap_on_disk/HashmapMain.TypesExternal.fsti
new file mode 100644
index 00000000..75747408
--- /dev/null
+++ b/tests/fstar-split/hashmap_on_disk/HashmapMain.TypesExternal.fsti
@@ -0,0 +1,10 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [hashmap_main]: external type declarations *)
+module HashmapMain.TypesExternal
+open Primitives
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** The state type used in the state-error monad *)
+val state : Type0
+
diff --git a/tests/fstar-split/hashmap_on_disk/Makefile b/tests/fstar-split/hashmap_on_disk/Makefile
new file mode 100644
index 00000000..fa7d1f36
--- /dev/null
+++ b/tests/fstar-split/hashmap_on_disk/Makefile
@@ -0,0 +1,49 @@
+# This file was automatically generated - modify ../Makefile.template instead
+INCLUDE_DIRS = .
+
+FSTAR_INCLUDES = $(addprefix --include ,$(INCLUDE_DIRS))
+
+FSTAR_HINTS ?= --use_hints --use_hint_hashes --record_hints
+
+FSTAR_OPTIONS = $(FSTAR_HINTS) \
+  --cache_checked_modules $(FSTAR_INCLUDES) --cmi \
+  --warn_error '+241@247+285-274' \
+
+FSTAR_EXE ?= fstar.exe
+FSTAR_NO_FLAGS = $(FSTAR_EXE) --already_cached 'Prims FStar LowStar Steel' --odir obj --cache_dir obj
+
+FSTAR = $(FSTAR_NO_FLAGS) $(FSTAR_OPTIONS)
+
+# The F* roots are used to compute the dependency graph, and generate the .depend file
+FSTAR_ROOTS ?= $(wildcard *.fst *.fsti)
+
+# Build all the files
+all: $(addprefix obj/,$(addsuffix .checked,$(FSTAR_ROOTS)))
+
+# This is the right way to ensure the .depend file always gets re-built.
+ifeq (,$(filter %-in,$(MAKECMDGOALS)))
+ifndef NODEPEND
+ifndef MAKE_RESTARTS
+.depend: .FORCE
+	$(FSTAR_NO_FLAGS) --dep full $(notdir $(FSTAR_ROOTS)) > $@
+
+.PHONY: .FORCE
+.FORCE:
+endif
+endif
+
+include .depend
+endif
+
+# For the interactive mode
+%.fst-in %.fsti-in:
+	@echo $(FSTAR_OPTIONS)
+
+# Generete the .checked files in batch mode
+%.checked:
+	$(FSTAR) $(FSTAR_OPTIONS) $< && \
+	touch -c $@
+
+.PHONY: clean
+clean:
+	rm -f obj/*
diff --git a/tests/fstar-split/hashmap_on_disk/Primitives.fst b/tests/fstar-split/hashmap_on_disk/Primitives.fst
new file mode 100644
index 00000000..a3ffbde4
--- /dev/null
+++ b/tests/fstar-split/hashmap_on_disk/Primitives.fst
@@ -0,0 +1,884 @@
+/// This file lists primitive and assumed functions and types
+module Primitives
+open FStar.Mul
+open FStar.List.Tot
+
+#set-options "--z3rlimit 15 --fuel 0 --ifuel 1"
+
+(*** Utilities *)
+val list_update (#a : Type0) (ls : list a) (i : nat{i < length ls}) (x : a) :
+  ls':list a{
+    length ls' = length ls /\
+    index ls' i == x
+  }
+#push-options "--fuel 1"
+let rec list_update #a ls i x =
+  match ls with
+  | x' :: ls -> if i = 0 then x :: ls else x' :: list_update ls (i-1) x
+#pop-options
+
+(*** Result *)
+type error : Type0 =
+| Failure
+| OutOfFuel
+
+type result (a : Type0) : Type0 =
+| Return : v:a -> result a
+| Fail : e:error -> result a
+
+// Monadic return operator
+unfold let return (#a : Type0) (x : a) : result a = Return x
+
+// Monadic bind operator.
+// Allows to use the notation:
+// ```
+// let* x = y in
+// ...
+// ```
+unfold let (let*) (#a #b : Type0) (m: result a)
+  (f: (x:a) -> Pure (result b) (requires (m == Return x)) (ensures fun _ -> True)) :
+  result b =
+  match m with
+  | Return x -> f x
+  | Fail e   -> Fail e
+
+// Monadic assert(...)
+let massert (b:bool) : result unit = if b then Return () else Fail Failure
+
+// Normalize and unwrap a successful result (used for globals).
+let eval_global (#a : Type0) (x : result a{Return? (normalize_term x)}) : a = Return?.v x
+
+(*** Misc *)
+type char = FStar.Char.char
+type string = string
+
+let is_zero (n: nat) : bool = n = 0
+let decrease (n: nat{n > 0}) : nat = n - 1
+
+let core_mem_replace (a : Type0) (x : a) (y : a) : a = x
+let core_mem_replace_back (a : Type0) (x : a) (y : a) : a = y
+
+// We don't really use raw pointers for now
+type mut_raw_ptr (t : Type0) = { v : t }
+type const_raw_ptr (t : Type0) = { v : t }
+
+(*** Scalars *)
+/// Rem.: most of the following code was partially generated
+
+assume val size_numbits : pos
+
+// TODO: we could use FStar.Int.int_t and FStar.UInt.int_t
+
+let isize_min : int = -9223372036854775808 // TODO: should be opaque
+let isize_max : int = 9223372036854775807 // TODO: should be opaque
+let i8_min : int = -128
+let i8_max : int = 127
+let i16_min : int = -32768
+let i16_max : int = 32767
+let i32_min : int = -2147483648
+let i32_max : int = 2147483647
+let i64_min : int = -9223372036854775808
+let i64_max : int = 9223372036854775807
+let i128_min : int = -170141183460469231731687303715884105728
+let i128_max : int = 170141183460469231731687303715884105727
+let usize_min : int = 0
+let usize_max : int = 4294967295 // TODO: should be opaque
+let u8_min : int = 0
+let u8_max : int = 255
+let u16_min : int = 0
+let u16_max : int = 65535
+let u32_min : int = 0
+let u32_max : int = 4294967295
+let u64_min : int = 0
+let u64_max : int = 18446744073709551615
+let u128_min : int = 0
+let u128_max : int = 340282366920938463463374607431768211455
+
+type scalar_ty =
+| Isize
+| I8
+| I16
+| I32
+| I64
+| I128
+| Usize
+| U8
+| U16
+| U32
+| U64
+| U128
+
+let is_unsigned = function
+  | Isize | I8 | I16 | I32 | I64 | I128 -> false
+  | Usize | U8 | U16 | U32 | U64 | U128 -> true
+
+let scalar_min (ty : scalar_ty) : int =
+  match ty with
+  | Isize -> isize_min
+  | I8 -> i8_min
+  | I16 -> i16_min
+  | I32 -> i32_min
+  | I64 -> i64_min
+  | I128 -> i128_min
+  | Usize -> usize_min
+  | U8 -> u8_min
+  | U16 -> u16_min
+  | U32 -> u32_min
+  | U64 -> u64_min
+  | U128 -> u128_min
+
+let scalar_max (ty : scalar_ty) : int =
+  match ty with
+  | Isize -> isize_max
+  | I8 -> i8_max
+  | I16 -> i16_max
+  | I32 -> i32_max
+  | I64 -> i64_max
+  | I128 -> i128_max
+  | Usize -> usize_max
+  | U8 -> u8_max
+  | U16 -> u16_max
+  | U32 -> u32_max
+  | U64 -> u64_max
+  | U128 -> u128_max
+
+type scalar (ty : scalar_ty) : eqtype = x:int{scalar_min ty <= x && x <= scalar_max ty}
+
+let mk_scalar (ty : scalar_ty) (x : int) : result (scalar ty) =
+  if scalar_min ty <= x && scalar_max ty >= x then Return x else Fail Failure
+
+let scalar_neg (#ty : scalar_ty) (x : scalar ty) : result (scalar ty) = mk_scalar ty (-x)
+
+let scalar_div (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  if y <> 0 then mk_scalar ty (x / y) else Fail Failure
+
+/// The remainder operation
+let int_rem (x : int) (y : int{y <> 0}) : int =
+  if x >= 0 then (x % y) else -(x % y)
+
+(* Checking consistency with Rust *)
+let _ = assert_norm(int_rem 1 2 = 1)
+let _ = assert_norm(int_rem (-1) 2 = -1)
+let _ = assert_norm(int_rem 1 (-2) = 1)
+let _ = assert_norm(int_rem (-1) (-2) = -1)
+
+let scalar_rem (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  if y <> 0 then mk_scalar ty (int_rem x y) else Fail Failure
+
+let scalar_add (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  mk_scalar ty (x + y)
+
+let scalar_sub (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  mk_scalar ty (x - y)
+
+let scalar_mul (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  mk_scalar ty (x * y)
+
+let scalar_xor (#ty : scalar_ty)
+    (x : scalar ty) (y : scalar ty) : scalar ty =
+  match ty with
+  | U8 -> FStar.UInt.logxor #8 x y
+  | U16 -> FStar.UInt.logxor #16 x y
+  | U32 -> FStar.UInt.logxor #32 x y
+  | U64 -> FStar.UInt.logxor #64 x y
+  | U128 -> FStar.UInt.logxor #128 x y
+  | Usize -> admit() // TODO
+  | I8 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 8);
+    normalize_spec (scalar I8);
+    FStar.Int.logxor #8 x y
+  | I16 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 16);
+    normalize_spec (scalar I16);
+    FStar.Int.logxor #16 x y
+  | I32 -> FStar.Int.logxor #32 x y
+  | I64 -> FStar.Int.logxor #64 x y
+  | I128 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 128);
+    normalize_spec (scalar I128);
+    FStar.Int.logxor #128 x y
+  | Isize -> admit() // TODO
+
+let scalar_or (#ty : scalar_ty)
+    (x : scalar ty) (y : scalar ty) : scalar ty =
+  match ty with
+  | U8 -> FStar.UInt.logor #8 x y
+  | U16 -> FStar.UInt.logor #16 x y
+  | U32 -> FStar.UInt.logor #32 x y
+  | U64 -> FStar.UInt.logor #64 x y
+  | U128 -> FStar.UInt.logor #128 x y
+  | Usize -> admit() // TODO
+  | I8 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 8);
+    normalize_spec (scalar I8);
+    FStar.Int.logor #8 x y
+  | I16 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 16);
+    normalize_spec (scalar I16);
+    FStar.Int.logor #16 x y
+  | I32 -> FStar.Int.logor #32 x y
+  | I64 -> FStar.Int.logor #64 x y
+  | I128 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 128);
+    normalize_spec (scalar I128);
+    FStar.Int.logor #128 x y
+  | Isize -> admit() // TODO
+
+let scalar_and (#ty : scalar_ty)
+    (x : scalar ty) (y : scalar ty) : scalar ty =
+  match ty with
+  | U8 -> FStar.UInt.logand #8 x y
+  | U16 -> FStar.UInt.logand #16 x y
+  | U32 -> FStar.UInt.logand #32 x y
+  | U64 -> FStar.UInt.logand #64 x y
+  | U128 -> FStar.UInt.logand #128 x y
+  | Usize -> admit() // TODO
+  | I8 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 8);
+    normalize_spec (scalar I8);
+    FStar.Int.logand #8 x y
+  | I16 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 16);
+    normalize_spec (scalar I16);
+    FStar.Int.logand #16 x y
+  | I32 -> FStar.Int.logand #32 x y
+  | I64 -> FStar.Int.logand #64 x y
+  | I128 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 128);
+    normalize_spec (scalar I128);
+    FStar.Int.logand #128 x y
+  | Isize -> admit() // TODO
+
+// Shift left
+let scalar_shl (#ty0 #ty1 : scalar_ty)
+    (x : scalar ty0) (y : scalar ty1) : result (scalar ty0) =
+  admit()
+
+// Shift right
+let scalar_shr (#ty0 #ty1 : scalar_ty)
+    (x : scalar ty0) (y : scalar ty1) : result (scalar ty0) =
+  admit()
+
+(** Cast an integer from a [src_ty] to a [tgt_ty] *)
+// TODO: check the semantics of casts in Rust
+let scalar_cast (src_ty : scalar_ty) (tgt_ty : scalar_ty) (x : scalar src_ty) : result (scalar tgt_ty) =
+  mk_scalar tgt_ty x
+
+// This can't fail, but for now we make all casts faillible (easier for the translation)
+let scalar_cast_bool (tgt_ty : scalar_ty) (x : bool) : result (scalar tgt_ty) =
+  mk_scalar tgt_ty (if x then 1 else 0)
+
+/// The scalar types
+type isize : eqtype = scalar Isize
+type i8    : eqtype = scalar I8
+type i16   : eqtype = scalar I16
+type i32   : eqtype = scalar I32
+type i64   : eqtype = scalar I64
+type i128  : eqtype = scalar I128
+type usize : eqtype = scalar Usize
+type u8    : eqtype = scalar U8
+type u16   : eqtype = scalar U16
+type u32   : eqtype = scalar U32
+type u64   : eqtype = scalar U64
+type u128  : eqtype = scalar U128
+
+
+let core_isize_min : isize = isize_min
+let core_isize_max : isize = isize_max
+let core_i8_min    : i8 = i8_min
+let core_i8_max    : i8 = i8_max
+let core_i16_min   : i16 = i16_min
+let core_i16_max   : i16 = i16_max
+let core_i32_min   : i32 = i32_min
+let core_i32_max   : i32 = i32_max
+let core_i64_min   : i64 = i64_min
+let core_i64_max   : i64 = i64_max
+let core_i128_min  : i128 = i128_min
+let core_i128_max  : i128 = i128_max
+
+let core_usize_min : usize = usize_min
+let core_usize_max : usize = usize_max
+let core_u8_min    : u8 = u8_min
+let core_u8_max    : u8 = u8_max
+let core_u16_min   : u16 = u16_min
+let core_u16_max   : u16 = u16_max
+let core_u32_min   : u32 = u32_min
+let core_u32_max   : u32 = u32_max
+let core_u64_min   : u64 = u64_min
+let core_u64_max   : u64 = u64_max
+let core_u128_min  : u128 = u128_min
+let core_u128_max  : u128 = u128_max
+
+/// Negation
+let isize_neg = scalar_neg #Isize
+let i8_neg = scalar_neg #I8
+let i16_neg = scalar_neg #I16
+let i32_neg = scalar_neg #I32
+let i64_neg = scalar_neg #I64
+let i128_neg = scalar_neg #I128
+
+/// Division
+let isize_div = scalar_div #Isize
+let i8_div = scalar_div #I8
+let i16_div = scalar_div #I16
+let i32_div = scalar_div #I32
+let i64_div = scalar_div #I64
+let i128_div = scalar_div #I128
+let usize_div = scalar_div #Usize
+let u8_div = scalar_div #U8
+let u16_div = scalar_div #U16
+let u32_div = scalar_div #U32
+let u64_div = scalar_div #U64
+let u128_div = scalar_div #U128
+
+/// Remainder
+let isize_rem = scalar_rem #Isize
+let i8_rem = scalar_rem #I8
+let i16_rem = scalar_rem #I16
+let i32_rem = scalar_rem #I32
+let i64_rem = scalar_rem #I64
+let i128_rem = scalar_rem #I128
+let usize_rem = scalar_rem #Usize
+let u8_rem = scalar_rem #U8
+let u16_rem = scalar_rem #U16
+let u32_rem = scalar_rem #U32
+let u64_rem = scalar_rem #U64
+let u128_rem = scalar_rem #U128
+
+/// Addition
+let isize_add = scalar_add #Isize
+let i8_add = scalar_add #I8
+let i16_add = scalar_add #I16
+let i32_add = scalar_add #I32
+let i64_add = scalar_add #I64
+let i128_add = scalar_add #I128
+let usize_add = scalar_add #Usize
+let u8_add = scalar_add #U8
+let u16_add = scalar_add #U16
+let u32_add = scalar_add #U32
+let u64_add = scalar_add #U64
+let u128_add = scalar_add #U128
+
+/// Subtraction
+let isize_sub = scalar_sub #Isize
+let i8_sub = scalar_sub #I8
+let i16_sub = scalar_sub #I16
+let i32_sub = scalar_sub #I32
+let i64_sub = scalar_sub #I64
+let i128_sub = scalar_sub #I128
+let usize_sub = scalar_sub #Usize
+let u8_sub = scalar_sub #U8
+let u16_sub = scalar_sub #U16
+let u32_sub = scalar_sub #U32
+let u64_sub = scalar_sub #U64
+let u128_sub = scalar_sub #U128
+
+/// Multiplication
+let isize_mul = scalar_mul #Isize
+let i8_mul = scalar_mul #I8
+let i16_mul = scalar_mul #I16
+let i32_mul = scalar_mul #I32
+let i64_mul = scalar_mul #I64
+let i128_mul = scalar_mul #I128
+let usize_mul = scalar_mul #Usize
+let u8_mul = scalar_mul #U8
+let u16_mul = scalar_mul #U16
+let u32_mul = scalar_mul #U32
+let u64_mul = scalar_mul #U64
+let u128_mul = scalar_mul #U128
+
+/// Xor
+let u8_xor = scalar_xor #U8
+let u16_xor = scalar_xor #U16
+let u32_xor = scalar_xor #U32
+let u64_xor = scalar_xor #U64
+let u128_xor = scalar_xor #U128
+let usize_xor = scalar_xor #Usize
+let i8_xor = scalar_xor #I8
+let i16_xor = scalar_xor #I16
+let i32_xor = scalar_xor #I32
+let i64_xor = scalar_xor #I64
+let i128_xor = scalar_xor #I128
+let isize_xor = scalar_xor #Isize
+
+/// Or
+let u8_or = scalar_or #U8
+let u16_or = scalar_or #U16
+let u32_or = scalar_or #U32
+let u64_or = scalar_or #U64
+let u128_or = scalar_or #U128
+let usize_or = scalar_or #Usize
+let i8_or = scalar_or #I8
+let i16_or = scalar_or #I16
+let i32_or = scalar_or #I32
+let i64_or = scalar_or #I64
+let i128_or = scalar_or #I128
+let isize_or = scalar_or #Isize
+
+/// And
+let u8_and = scalar_and #U8
+let u16_and = scalar_and #U16
+let u32_and = scalar_and #U32
+let u64_and = scalar_and #U64
+let u128_and = scalar_and #U128
+let usize_and = scalar_and #Usize
+let i8_and = scalar_and #I8
+let i16_and = scalar_and #I16
+let i32_and = scalar_and #I32
+let i64_and = scalar_and #I64
+let i128_and = scalar_and #I128
+let isize_and = scalar_and #Isize
+
+/// Shift left
+let u8_shl #ty = scalar_shl #U8 #ty
+let u16_shl #ty = scalar_shl #U16 #ty
+let u32_shl #ty = scalar_shl #U32 #ty
+let u64_shl #ty = scalar_shl #U64 #ty
+let u128_shl #ty = scalar_shl #U128 #ty
+let usize_shl #ty = scalar_shl #Usize #ty
+let i8_shl #ty = scalar_shl #I8 #ty
+let i16_shl #ty = scalar_shl #I16 #ty
+let i32_shl #ty = scalar_shl #I32 #ty
+let i64_shl #ty = scalar_shl #I64 #ty
+let i128_shl #ty = scalar_shl #I128 #ty
+let isize_shl #ty = scalar_shl #Isize #ty
+
+/// Shift right
+let u8_shr #ty = scalar_shr #U8 #ty
+let u16_shr #ty = scalar_shr #U16 #ty
+let u32_shr #ty = scalar_shr #U32 #ty
+let u64_shr #ty = scalar_shr #U64 #ty
+let u128_shr #ty = scalar_shr #U128 #ty
+let usize_shr #ty = scalar_shr #Usize #ty
+let i8_shr #ty = scalar_shr #I8 #ty
+let i16_shr #ty = scalar_shr #I16 #ty
+let i32_shr #ty = scalar_shr #I32 #ty
+let i64_shr #ty = scalar_shr #I64 #ty
+let i128_shr #ty = scalar_shr #I128 #ty
+let isize_shr #ty = scalar_shr #Isize #ty
+
+(*** core::ops *)
+
+// Trait declaration: [core::ops::index::Index]
+noeq type core_ops_index_Index (self idx : Type0) = {
+  output : Type0;
+  index : self → idx → result output
+}
+
+// Trait declaration: [core::ops::index::IndexMut]
+noeq type core_ops_index_IndexMut (self idx : Type0) = {
+  indexInst : core_ops_index_Index self idx;
+  index_mut : self → idx → result indexInst.output;
+  index_mut_back : self → idx → indexInst.output → result self;
+}
+
+// Trait declaration [core::ops::deref::Deref]
+noeq type core_ops_deref_Deref (self : Type0) = {
+  target : Type0;
+  deref : self → result target;
+}
+
+// Trait declaration [core::ops::deref::DerefMut]
+noeq type core_ops_deref_DerefMut (self : Type0) = {
+  derefInst : core_ops_deref_Deref self;
+  deref_mut : self → result derefInst.target;
+  deref_mut_back : self → derefInst.target → result self;
+}
+
+type core_ops_range_Range (a : Type0) = {
+  start : a;
+  end_ : a;
+}
+
+(*** [alloc] *)
+
+let alloc_boxed_Box_deref (t : Type0) (x : t) : result t = Return x
+let alloc_boxed_Box_deref_mut (t : Type0) (x : t) : result t = Return x
+let alloc_boxed_Box_deref_mut_back (t : Type) (_ : t) (x : t) : result t = Return x
+
+// Trait instance
+let alloc_boxed_Box_coreopsDerefInst (self : Type0) : core_ops_deref_Deref self = {
+  target = self;
+  deref = alloc_boxed_Box_deref self;
+}
+
+// Trait instance
+let alloc_boxed_Box_coreopsDerefMutInst (self : Type0) : core_ops_deref_DerefMut self = {
+  derefInst = alloc_boxed_Box_coreopsDerefInst self;
+  deref_mut = alloc_boxed_Box_deref_mut self;
+  deref_mut_back = alloc_boxed_Box_deref_mut_back self;
+}
+
+(*** Array *)
+type array (a : Type0) (n : usize) = s:list a{length s = n}
+
+// We tried putting the normalize_term condition as a refinement on the list
+// but it didn't work. It works with the requires clause.
+let mk_array (a : Type0) (n : usize)
+  (l : list a) :
+  Pure (array a n)
+  (requires (normalize_term(FStar.List.Tot.length l) = n))
+  (ensures (fun _ -> True)) =
+  normalize_term_spec (FStar.List.Tot.length l);
+  l
+
+let array_index_usize (a : Type0) (n : usize) (x : array a n) (i : usize) : result a =
+  if i < length x then Return (index x i)
+  else Fail Failure
+
+let array_update_usize (a : Type0) (n : usize) (x : array a n) (i : usize) (nx : a) : result (array a n) =
+  if i < length x then Return (list_update x i nx)
+  else Fail Failure
+
+(*** Slice *)
+type slice (a : Type0) = s:list a{length s <= usize_max}
+
+let slice_len (a : Type0) (s : slice a) : usize = length s
+
+let slice_index_usize (a : Type0) (x : slice a) (i : usize) : result a =
+  if i < length x then Return (index x i)
+  else Fail Failure
+
+let slice_update_usize (a : Type0) (x : slice a) (i : usize) (nx : a) : result (slice a) =
+  if i < length x then Return (list_update x i nx)
+  else Fail Failure
+
+(*** Subslices *)
+
+let array_to_slice (a : Type0) (n : usize) (x : array a n) : result (slice a) = Return x
+let array_from_slice (a : Type0) (n : usize) (x : array a n) (s : slice a) : result (array a n) =
+  if length s = n then Return s
+  else Fail Failure
+
+// TODO: finish the definitions below (there lacks [List.drop] and [List.take] in the standard library *)
+let array_subslice (a : Type0) (n : usize) (x : array a n) (r : core_ops_range_Range usize) : result (slice a) =
+  admit()
+
+let array_update_subslice (a : Type0) (n : usize) (x : array a n) (r : core_ops_range_Range usize) (ns : slice a) : result (array a n) =
+  admit()
+
+let array_repeat (a : Type0) (n : usize) (x : a) : array a n =
+  admit()
+
+let slice_subslice (a : Type0) (x : slice a) (r : core_ops_range_Range usize) : result (slice a) =
+  admit()
+
+let slice_update_subslice (a : Type0) (x : slice a) (r : core_ops_range_Range usize) (ns : slice a) : result (slice a) =
+  admit()
+
+(*** Vector *)
+type alloc_vec_Vec (a : Type0) = v:list a{length v <= usize_max}
+
+let alloc_vec_Vec_new (a  : Type0) : alloc_vec_Vec a = assert_norm(length #a [] == 0); []
+let alloc_vec_Vec_len (a : Type0) (v : alloc_vec_Vec a) : usize = length v
+
+// Helper
+let alloc_vec_Vec_index_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) : result a =
+  if i < length v then Return (index v i) else Fail Failure
+// Helper
+let alloc_vec_Vec_update_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
+  if i < length v then Return (list_update v i x) else Fail Failure
+
+// The **forward** function shouldn't be used
+let alloc_vec_Vec_push_fwd (a  : Type0) (v : alloc_vec_Vec a) (x : a) : unit = ()
+let alloc_vec_Vec_push (a  : Type0) (v : alloc_vec_Vec a) (x : a) :
+  Pure (result (alloc_vec_Vec a))
+  (requires True)
+  (ensures (fun res ->
+    match res with
+    | Fail e -> e == Failure
+    | Return v' -> length v' = length v + 1)) =
+  if length v < usize_max then begin
+    (**) assert_norm(length [x] == 1);
+    (**) append_length v [x];
+    (**) assert(length (append v [x]) = length v + 1);
+    Return (append v [x])
+    end
+  else Fail Failure
+
+// The **forward** function shouldn't be used
+let alloc_vec_Vec_insert_fwd (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result unit =
+  if i < length v then Return () else Fail Failure
+let alloc_vec_Vec_insert (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
+  if i < length v then Return (list_update v i x) else Fail Failure
+
+// Trait declaration: [core::slice::index::private_slice_index::Sealed]
+type core_slice_index_private_slice_index_Sealed (self : Type0) = unit
+
+// Trait declaration: [core::slice::index::SliceIndex]
+noeq type core_slice_index_SliceIndex (self t : Type0) = {
+  sealedInst : core_slice_index_private_slice_index_Sealed self;
+  output : Type0;
+  get : self → t → result (option output);
+  get_mut : self → t → result (option output);
+  get_mut_back : self → t → option output → result t;
+  get_unchecked : self → const_raw_ptr t → result (const_raw_ptr output);
+  get_unchecked_mut : self → mut_raw_ptr t → result (mut_raw_ptr output);
+  index : self → t → result output;
+  index_mut : self → t → result output;
+  index_mut_back : self → t → output → result t;
+}
+
+// [core::slice::index::[T]::index]: forward function
+let core_slice_index_Slice_index
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (s : slice t) (i : idx) : result inst.output =
+  let* x = inst.get i s in
+  match x with
+  | None -> Fail Failure
+  | Some x -> Return x
+
+// [core::slice::index::Range:::get]: forward function
+let core_slice_index_RangeUsize_get (t : Type0) (i : core_ops_range_Range usize) (s : slice t) :
+  result (option (slice t)) =
+  admit () // TODO
+
+// [core::slice::index::Range::get_mut]: forward function
+let core_slice_index_RangeUsize_get_mut
+  (t : Type0) : core_ops_range_Range usize → slice t → result (option (slice t)) =
+  admit () // TODO
+
+// [core::slice::index::Range::get_mut]: backward function 0
+let core_slice_index_RangeUsize_get_mut_back
+  (t : Type0) :
+  core_ops_range_Range usize → slice t → option (slice t) → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::Range::get_unchecked]: forward function
+let core_slice_index_RangeUsize_get_unchecked
+  (t : Type0) :
+  core_ops_range_Range usize → const_raw_ptr (slice t) → result (const_raw_ptr (slice t)) =
+  // Don't know what the model should be - for now we always fail to make
+  // sure code which uses it fails
+  fun _ _ -> Fail Failure
+
+// [core::slice::index::Range::get_unchecked_mut]: forward function
+let core_slice_index_RangeUsize_get_unchecked_mut
+  (t : Type0) :
+  core_ops_range_Range usize → mut_raw_ptr (slice t) → result (mut_raw_ptr (slice t)) =
+  // Don't know what the model should be - for now we always fail to make
+  // sure code which uses it fails
+  fun _ _ -> Fail Failure
+
+// [core::slice::index::Range::index]: forward function
+let core_slice_index_RangeUsize_index
+  (t : Type0) : core_ops_range_Range usize → slice t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::Range::index_mut]: forward function
+let core_slice_index_RangeUsize_index_mut
+  (t : Type0) : core_ops_range_Range usize → slice t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::Range::index_mut]: backward function 0
+let core_slice_index_RangeUsize_index_mut_back
+  (t : Type0) : core_ops_range_Range usize → slice t → slice t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::[T]::index_mut]: forward function
+let core_slice_index_Slice_index_mut
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
+  slice t → idx → result inst.output =
+  admit () // 
+
+// [core::slice::index::[T]::index_mut]: backward function 0
+let core_slice_index_Slice_index_mut_back
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
+  slice t → idx → inst.output → result (slice t) =
+  admit () // TODO
+
+// [core::array::[T; N]::index]: forward function
+let core_array_Array_index
+  (t idx : Type0) (n : usize) (inst : core_ops_index_Index (slice t) idx)
+  (a : array t n) (i : idx) : result inst.output =
+  admit () // TODO
+
+// [core::array::[T; N]::index_mut]: forward function
+let core_array_Array_index_mut
+  (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
+  (a : array t n) (i : idx) : result inst.indexInst.output =
+  admit () // TODO
+
+// [core::array::[T; N]::index_mut]: backward function 0
+let core_array_Array_index_mut_back
+  (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
+  (a : array t n) (i : idx) (x : inst.indexInst.output) : result (array t n) =
+  admit () // TODO
+
+// Trait implementation: [core::slice::index::private_slice_index::Range]
+let core_slice_index_private_slice_index_SealedRangeUsizeInst
+  : core_slice_index_private_slice_index_Sealed (core_ops_range_Range usize) = ()
+
+// Trait implementation: [core::slice::index::Range]
+let core_slice_index_SliceIndexRangeUsizeSliceTInst (t : Type0) :
+  core_slice_index_SliceIndex (core_ops_range_Range usize) (slice t) = {
+  sealedInst = core_slice_index_private_slice_index_SealedRangeUsizeInst;
+  output = slice t;
+  get = core_slice_index_RangeUsize_get t;
+  get_mut = core_slice_index_RangeUsize_get_mut t;
+  get_mut_back = core_slice_index_RangeUsize_get_mut_back t;
+  get_unchecked = core_slice_index_RangeUsize_get_unchecked t;
+  get_unchecked_mut = core_slice_index_RangeUsize_get_unchecked_mut t;
+  index = core_slice_index_RangeUsize_index t;
+  index_mut = core_slice_index_RangeUsize_index_mut t;
+  index_mut_back = core_slice_index_RangeUsize_index_mut_back t;
+}
+
+// Trait implementation: [core::slice::index::[T]]
+let core_ops_index_IndexSliceTIInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_Index (slice t) idx = {
+  output = inst.output;
+  index = core_slice_index_Slice_index t idx inst;
+}
+
+// Trait implementation: [core::slice::index::[T]]
+let core_ops_index_IndexMutSliceTIInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_IndexMut (slice t) idx = {
+  indexInst = core_ops_index_IndexSliceTIInst t idx inst;
+  index_mut = core_slice_index_Slice_index_mut t idx inst;
+  index_mut_back = core_slice_index_Slice_index_mut_back t idx inst;
+}
+
+// Trait implementation: [core::array::[T; N]]
+let core_ops_index_IndexArrayInst (t idx : Type0) (n : usize)
+  (inst : core_ops_index_Index (slice t) idx) :
+  core_ops_index_Index (array t n) idx = {
+  output = inst.output;
+  index = core_array_Array_index t idx n inst;
+}
+
+// Trait implementation: [core::array::[T; N]]
+let core_ops_index_IndexMutArrayIInst (t idx : Type0) (n : usize)
+  (inst : core_ops_index_IndexMut (slice t) idx) :
+  core_ops_index_IndexMut (array t n) idx = {
+  indexInst = core_ops_index_IndexArrayInst t idx n inst.indexInst;
+  index_mut = core_array_Array_index_mut t idx n inst;
+  index_mut_back = core_array_Array_index_mut_back t idx n inst;
+}
+
+// [core::slice::index::usize::get]: forward function
+let core_slice_index_usize_get
+  (t : Type0) : usize → slice t → result (option t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_mut]: forward function
+let core_slice_index_usize_get_mut
+  (t : Type0) : usize → slice t → result (option t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_mut]: backward function 0
+let core_slice_index_usize_get_mut_back
+  (t : Type0) : usize → slice t → option t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_unchecked]: forward function
+let core_slice_index_usize_get_unchecked
+  (t : Type0) : usize → const_raw_ptr (slice t) → result (const_raw_ptr t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_unchecked_mut]: forward function
+let core_slice_index_usize_get_unchecked_mut
+  (t : Type0) : usize → mut_raw_ptr (slice t) → result (mut_raw_ptr t) =
+  admit () // TODO
+
+// [core::slice::index::usize::index]: forward function
+let core_slice_index_usize_index (t : Type0) : usize → slice t → result t =
+  admit () // TODO
+
+// [core::slice::index::usize::index_mut]: forward function
+let core_slice_index_usize_index_mut (t : Type0) : usize → slice t → result t =
+  admit () // TODO
+
+// [core::slice::index::usize::index_mut]: backward function 0
+let core_slice_index_usize_index_mut_back
+  (t : Type0) : usize → slice t → t → result (slice t) =
+  admit () // TODO
+
+// Trait implementation: [core::slice::index::private_slice_index::usize]
+let core_slice_index_private_slice_index_SealedUsizeInst
+  : core_slice_index_private_slice_index_Sealed usize = ()
+
+// Trait implementation: [core::slice::index::usize]
+let core_slice_index_SliceIndexUsizeSliceTInst (t : Type0) :
+  core_slice_index_SliceIndex usize (slice t) = {
+  sealedInst = core_slice_index_private_slice_index_SealedUsizeInst;
+  output = t;
+  get = core_slice_index_usize_get t;
+  get_mut = core_slice_index_usize_get_mut t;
+  get_mut_back = core_slice_index_usize_get_mut_back t;
+  get_unchecked = core_slice_index_usize_get_unchecked t;
+  get_unchecked_mut = core_slice_index_usize_get_unchecked_mut t;
+  index = core_slice_index_usize_index t;
+  index_mut = core_slice_index_usize_index_mut t;
+  index_mut_back = core_slice_index_usize_index_mut_back t;
+}
+
+// [alloc::vec::Vec::index]: forward function
+let alloc_vec_Vec_index (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (self : alloc_vec_Vec t) (i : idx) : result inst.output =
+  admit () // TODO
+
+// [alloc::vec::Vec::index_mut]: forward function
+let alloc_vec_Vec_index_mut (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (self : alloc_vec_Vec t) (i : idx) : result inst.output =
+  admit () // TODO
+
+// [alloc::vec::Vec::index_mut]: backward function 0
+let alloc_vec_Vec_index_mut_back
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (self : alloc_vec_Vec t) (i : idx) (x : inst.output) : result (alloc_vec_Vec t) =
+  admit () // TODO
+
+// Trait implementation: [alloc::vec::Vec]
+let alloc_vec_Vec_coreopsindexIndexInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_Index (alloc_vec_Vec t) idx = {
+  output = inst.output;
+  index = alloc_vec_Vec_index t idx inst;
+}
+
+// Trait implementation: [alloc::vec::Vec]
+let alloc_vec_Vec_coreopsindexIndexMutInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_IndexMut (alloc_vec_Vec t) idx = {
+  indexInst = alloc_vec_Vec_coreopsindexIndexInst t idx inst;
+  index_mut = alloc_vec_Vec_index_mut t idx inst;
+  index_mut_back = alloc_vec_Vec_index_mut_back t idx inst;
+}
+
+(*** Theorems *)
+
+let alloc_vec_Vec_index_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
+  Lemma (
+    alloc_vec_Vec_index a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i ==
+      alloc_vec_Vec_index_usize v i)
+  [SMTPat (alloc_vec_Vec_index a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i)]
+  =
+  admit()
+
+let alloc_vec_Vec_index_mut_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
+  Lemma (
+    alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i ==
+      alloc_vec_Vec_index_usize v i)
+  [SMTPat (alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i)]
+  =
+  admit()
+
+let alloc_vec_Vec_index_mut_back_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) :
+  Lemma (
+    alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x ==
+      alloc_vec_Vec_update_usize v i x)
+  [SMTPat (alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x)]
+  =
+  admit()
diff --git a/tests/fstar-split/misc/Bitwise.fst b/tests/fstar-split/misc/Bitwise.fst
new file mode 100644
index 00000000..d7ba2c57
--- /dev/null
+++ b/tests/fstar-split/misc/Bitwise.fst
@@ -0,0 +1,32 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [bitwise] *)
+module Bitwise
+open Primitives
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [bitwise::shift_u32]: forward function
+    Source: 'src/bitwise.rs', lines 3:0-3:31 *)
+let shift_u32 (a : u32) : result u32 =
+  let* t = u32_shr #Usize a 16 in u32_shl #Usize t 16
+
+(** [bitwise::shift_i32]: forward function
+    Source: 'src/bitwise.rs', lines 10:0-10:31 *)
+let shift_i32 (a : i32) : result i32 =
+  let* t = i32_shr #Isize a 16 in i32_shl #Isize t 16
+
+(** [bitwise::xor_u32]: forward function
+    Source: 'src/bitwise.rs', lines 17:0-17:37 *)
+let xor_u32 (a : u32) (b : u32) : result u32 =
+  Return (u32_xor a b)
+
+(** [bitwise::or_u32]: forward function
+    Source: 'src/bitwise.rs', lines 21:0-21:36 *)
+let or_u32 (a : u32) (b : u32) : result u32 =
+  Return (u32_or a b)
+
+(** [bitwise::and_u32]: forward function
+    Source: 'src/bitwise.rs', lines 25:0-25:37 *)
+let and_u32 (a : u32) (b : u32) : result u32 =
+  Return (u32_and a b)
+
diff --git a/tests/fstar-split/misc/Constants.fst b/tests/fstar-split/misc/Constants.fst
new file mode 100644
index 00000000..7e56cc20
--- /dev/null
+++ b/tests/fstar-split/misc/Constants.fst
@@ -0,0 +1,145 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [constants] *)
+module Constants
+open Primitives
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [constants::X0]
+    Source: 'src/constants.rs', lines 5:0-5:17 *)
+let x0_body : result u32 = Return 0
+let x0_c : u32 = eval_global x0_body
+
+(** [constants::X1]
+    Source: 'src/constants.rs', lines 7:0-7:17 *)
+let x1_body : result u32 = Return core_u32_max
+let x1_c : u32 = eval_global x1_body
+
+(** [constants::X2]
+    Source: 'src/constants.rs', lines 10:0-10:17 *)
+let x2_body : result u32 = Return 3
+let x2_c : u32 = eval_global x2_body
+
+(** [constants::incr]: forward function
+    Source: 'src/constants.rs', lines 17:0-17:32 *)
+let incr (n : u32) : result u32 =
+  u32_add n 1
+
+(** [constants::X3]
+    Source: 'src/constants.rs', lines 15:0-15:17 *)
+let x3_body : result u32 = incr 32
+let x3_c : u32 = eval_global x3_body
+
+(** [constants::mk_pair0]: forward function
+    Source: 'src/constants.rs', lines 23:0-23:51 *)
+let mk_pair0 (x : u32) (y : u32) : result (u32 & u32) =
+  Return (x, y)
+
+(** [constants::Pair]
+    Source: 'src/constants.rs', lines 36:0-36:23 *)
+type pair_t (t1 t2 : Type0) = { x : t1; y : t2; }
+
+(** [constants::mk_pair1]: forward function
+    Source: 'src/constants.rs', lines 27:0-27:55 *)
+let mk_pair1 (x : u32) (y : u32) : result (pair_t u32 u32) =
+  Return { x = x; y = y }
+
+(** [constants::P0]
+    Source: 'src/constants.rs', lines 31:0-31:24 *)
+let p0_body : result (u32 & u32) = mk_pair0 0 1
+let p0_c : (u32 & u32) = eval_global p0_body
+
+(** [constants::P1]
+    Source: 'src/constants.rs', lines 32:0-32:28 *)
+let p1_body : result (pair_t u32 u32) = mk_pair1 0 1
+let p1_c : pair_t u32 u32 = eval_global p1_body
+
+(** [constants::P2]
+    Source: 'src/constants.rs', lines 33:0-33:24 *)
+let p2_body : result (u32 & u32) = Return (0, 1)
+let p2_c : (u32 & u32) = eval_global p2_body
+
+(** [constants::P3]
+    Source: 'src/constants.rs', lines 34:0-34:28 *)
+let p3_body : result (pair_t u32 u32) = Return { x = 0; y = 1 }
+let p3_c : pair_t u32 u32 = eval_global p3_body
+
+(** [constants::Wrap]
+    Source: 'src/constants.rs', lines 49:0-49:18 *)
+type wrap_t (t : Type0) = { value : t; }
+
+(** [constants::{constants::Wrap<T>}::new]: forward function
+    Source: 'src/constants.rs', lines 54:4-54:41 *)
+let wrap_new (t : Type0) (value : t) : result (wrap_t t) =
+  Return { value = value }
+
+(** [constants::Y]
+    Source: 'src/constants.rs', lines 41:0-41:22 *)
+let y_body : result (wrap_t i32) = wrap_new i32 2
+let y_c : wrap_t i32 = eval_global y_body
+
+(** [constants::unwrap_y]: forward function
+    Source: 'src/constants.rs', lines 43:0-43:30 *)
+let unwrap_y : result i32 =
+  Return y_c.value
+
+(** [constants::YVAL]
+    Source: 'src/constants.rs', lines 47:0-47:19 *)
+let yval_body : result i32 = unwrap_y
+let yval_c : i32 = eval_global yval_body
+
+(** [constants::get_z1::Z1]
+    Source: 'src/constants.rs', lines 62:4-62:17 *)
+let get_z1_z1_body : result i32 = Return 3
+let get_z1_z1_c : i32 = eval_global get_z1_z1_body
+
+(** [constants::get_z1]: forward function
+    Source: 'src/constants.rs', lines 61:0-61:28 *)
+let get_z1 : result i32 =
+  Return get_z1_z1_c
+
+(** [constants::add]: forward function
+    Source: 'src/constants.rs', lines 66:0-66:39 *)
+let add (a : i32) (b : i32) : result i32 =
+  i32_add a b
+
+(** [constants::Q1]
+    Source: 'src/constants.rs', lines 74:0-74:17 *)
+let q1_body : result i32 = Return 5
+let q1_c : i32 = eval_global q1_body
+
+(** [constants::Q2]
+    Source: 'src/constants.rs', lines 75:0-75:17 *)
+let q2_body : result i32 = Return q1_c
+let q2_c : i32 = eval_global q2_body
+
+(** [constants::Q3]
+    Source: 'src/constants.rs', lines 76:0-76:17 *)
+let q3_body : result i32 = add q2_c 3
+let q3_c : i32 = eval_global q3_body
+
+(** [constants::get_z2]: forward function
+    Source: 'src/constants.rs', lines 70:0-70:28 *)
+let get_z2 : result i32 =
+  let* i = get_z1 in let* i1 = add i q3_c in add q1_c i1
+
+(** [constants::S1]
+    Source: 'src/constants.rs', lines 80:0-80:18 *)
+let s1_body : result u32 = Return 6
+let s1_c : u32 = eval_global s1_body
+
+(** [constants::S2]
+    Source: 'src/constants.rs', lines 81:0-81:18 *)
+let s2_body : result u32 = incr s1_c
+let s2_c : u32 = eval_global s2_body
+
+(** [constants::S3]
+    Source: 'src/constants.rs', lines 82:0-82:29 *)
+let s3_body : result (pair_t u32 u32) = Return p3_c
+let s3_c : pair_t u32 u32 = eval_global s3_body
+
+(** [constants::S4]
+    Source: 'src/constants.rs', lines 83:0-83:29 *)
+let s4_body : result (pair_t u32 u32) = mk_pair1 7 8
+let s4_c : pair_t u32 u32 = eval_global s4_body
+
diff --git a/tests/fstar-split/misc/External.Funs.fst b/tests/fstar-split/misc/External.Funs.fst
new file mode 100644
index 00000000..3b84697e
--- /dev/null
+++ b/tests/fstar-split/misc/External.Funs.fst
@@ -0,0 +1,84 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [external]: function definitions *)
+module External.Funs
+open Primitives
+include External.Types
+include External.FunsExternal
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [external::swap]: forward function
+    Source: 'src/external.rs', lines 6:0-6:46 *)
+let swap (t : Type0) (x : t) (y : t) (st : state) : result (state & unit) =
+  let* (st1, _) = core_mem_swap t x y st in
+  let* (st2, _) = core_mem_swap_back0 t x y st st1 in
+  let* (st3, _) = core_mem_swap_back1 t x y st st2 in
+  Return (st3, ())
+
+(** [external::swap]: backward function 0
+    Source: 'src/external.rs', lines 6:0-6:46 *)
+let swap_back
+  (t : Type0) (x : t) (y : t) (st : state) (st1 : state) :
+  result (state & (t & t))
+  =
+  let* (st2, _) = core_mem_swap t x y st in
+  let* (st3, x1) = core_mem_swap_back0 t x y st st2 in
+  let* (_, y1) = core_mem_swap_back1 t x y st st3 in
+  Return (st1, (x1, y1))
+
+(** [external::test_new_non_zero_u32]: forward function
+    Source: 'src/external.rs', lines 11:0-11:60 *)
+let test_new_non_zero_u32
+  (x : u32) (st : state) : result (state & core_num_nonzero_NonZeroU32_t) =
+  let* (st1, o) = core_num_nonzero_NonZeroU32_new x st in
+  core_option_Option_unwrap core_num_nonzero_NonZeroU32_t o st1
+
+(** [external::test_vec]: forward function
+    Source: 'src/external.rs', lines 17:0-17:17 *)
+let test_vec : result unit =
+  let v = alloc_vec_Vec_new u32 in
+  let* _ = alloc_vec_Vec_push u32 v 0 in
+  Return ()
+
+(** Unit test for [external::test_vec] *)
+let _ = assert_norm (test_vec = Return ())
+
+(** [external::custom_swap]: forward function
+    Source: 'src/external.rs', lines 24:0-24:66 *)
+let custom_swap (t : Type0) (x : t) (y : t) (st : state) : result (state & t) =
+  let* (st1, _) = core_mem_swap t x y st in
+  let* (st2, x1) = core_mem_swap_back0 t x y st st1 in
+  let* (st3, _) = core_mem_swap_back1 t x y st st2 in
+  Return (st3, x1)
+
+(** [external::custom_swap]: backward function 0
+    Source: 'src/external.rs', lines 24:0-24:66 *)
+let custom_swap_back
+  (t : Type0) (x : t) (y : t) (st : state) (ret : t) (st1 : state) :
+  result (state & (t & t))
+  =
+  let* (st2, _) = core_mem_swap t x y st in
+  let* (st3, _) = core_mem_swap_back0 t x y st st2 in
+  let* (_, y1) = core_mem_swap_back1 t x y st st3 in
+  Return (st1, (ret, y1))
+
+(** [external::test_custom_swap]: forward function
+    Source: 'src/external.rs', lines 29:0-29:59 *)
+let test_custom_swap (x : u32) (y : u32) (st : state) : result (state & unit) =
+  let* (st1, _) = custom_swap u32 x y st in Return (st1, ())
+
+(** [external::test_custom_swap]: backward function 0
+    Source: 'src/external.rs', lines 29:0-29:59 *)
+let test_custom_swap_back
+  (x : u32) (y : u32) (st : state) (st1 : state) :
+  result (state & (u32 & u32))
+  =
+  custom_swap_back u32 x y st 1 st1
+
+(** [external::test_swap_non_zero]: forward function
+    Source: 'src/external.rs', lines 35:0-35:44 *)
+let test_swap_non_zero (x : u32) (st : state) : result (state & u32) =
+  let* (st1, _) = swap u32 x 0 st in
+  let* (st2, (x1, _)) = swap_back u32 x 0 st st1 in
+  if x1 = 0 then Fail Failure else Return (st2, x1)
+
diff --git a/tests/fstar-split/misc/External.FunsExternal.fsti b/tests/fstar-split/misc/External.FunsExternal.fsti
new file mode 100644
index 00000000..923a1101
--- /dev/null
+++ b/tests/fstar-split/misc/External.FunsExternal.fsti
@@ -0,0 +1,32 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [external]: external function declarations *)
+module External.FunsExternal
+open Primitives
+include External.Types
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [core::mem::swap]: forward function
+    Source: '/rustc/d59363ad0b6391b7fc5bbb02c9ccf9300eef3753/library/core/src/mem/mod.rs', lines 726:0-726:42 *)
+val core_mem_swap (t : Type0) : t -> t -> state -> result (state & unit)
+
+(** [core::mem::swap]: backward function 0
+    Source: '/rustc/d59363ad0b6391b7fc5bbb02c9ccf9300eef3753/library/core/src/mem/mod.rs', lines 726:0-726:42 *)
+val core_mem_swap_back0
+  (t : Type0) : t -> t -> state -> state -> result (state & t)
+
+(** [core::mem::swap]: backward function 1
+    Source: '/rustc/d59363ad0b6391b7fc5bbb02c9ccf9300eef3753/library/core/src/mem/mod.rs', lines 726:0-726:42 *)
+val core_mem_swap_back1
+  (t : Type0) : t -> t -> state -> state -> result (state & t)
+
+(** [core::num::nonzero::{core::num::nonzero::NonZeroU32#14}::new]: forward function
+    Source: '/rustc/d59363ad0b6391b7fc5bbb02c9ccf9300eef3753/library/core/src/num/nonzero.rs', lines 79:16-79:57 *)
+val core_num_nonzero_NonZeroU32_new
+  : u32 -> state -> result (state & (option core_num_nonzero_NonZeroU32_t))
+
+(** [core::option::{core::option::Option<T>}::unwrap]: forward function
+    Source: '/rustc/d59363ad0b6391b7fc5bbb02c9ccf9300eef3753/library/core/src/option.rs', lines 932:4-932:34 *)
+val core_option_Option_unwrap
+  (t : Type0) : option t -> state -> result (state & t)
+
diff --git a/tests/fstar-split/misc/External.Types.fst b/tests/fstar-split/misc/External.Types.fst
new file mode 100644
index 00000000..4fbcec47
--- /dev/null
+++ b/tests/fstar-split/misc/External.Types.fst
@@ -0,0 +1,8 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [external]: type definitions *)
+module External.Types
+open Primitives
+include External.TypesExternal
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
diff --git a/tests/fstar-split/misc/External.TypesExternal.fsti b/tests/fstar-split/misc/External.TypesExternal.fsti
new file mode 100644
index 00000000..4bfbe0c5
--- /dev/null
+++ b/tests/fstar-split/misc/External.TypesExternal.fsti
@@ -0,0 +1,14 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [external]: external type declarations *)
+module External.TypesExternal
+open Primitives
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [core::num::nonzero::NonZeroU32]
+    Source: '/rustc/d59363ad0b6391b7fc5bbb02c9ccf9300eef3753/library/core/src/num/nonzero.rs', lines 50:12-50:33 *)
+val core_num_nonzero_NonZeroU32_t : Type0
+
+(** The state type used in the state-error monad *)
+val state : Type0
+
diff --git a/tests/fstar-split/misc/Loops.Clauses.Template.fst b/tests/fstar-split/misc/Loops.Clauses.Template.fst
new file mode 100644
index 00000000..6be351c6
--- /dev/null
+++ b/tests/fstar-split/misc/Loops.Clauses.Template.fst
@@ -0,0 +1,131 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [loops]: templates for the decreases clauses *)
+module Loops.Clauses.Template
+open Primitives
+open Loops.Types
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [loops::sum]: decreases clause
+    Source: 'src/loops.rs', lines 4:0-14:1 *)
+unfold let sum_loop_decreases (max : u32) (i : u32) (s : u32) : nat = admit ()
+
+(** [loops::sum_with_mut_borrows]: decreases clause
+    Source: 'src/loops.rs', lines 19:0-31:1 *)
+unfold
+let sum_with_mut_borrows_loop_decreases (max : u32) (mi : u32) (ms : u32) : nat
+  =
+  admit ()
+
+(** [loops::sum_with_shared_borrows]: decreases clause
+    Source: 'src/loops.rs', lines 34:0-48:1 *)
+unfold
+let sum_with_shared_borrows_loop_decreases (max : u32) (i : u32) (s : u32) :
+  nat =
+  admit ()
+
+(** [loops::clear]: decreases clause
+    Source: 'src/loops.rs', lines 52:0-58:1 *)
+unfold
+let clear_loop_decreases (v : alloc_vec_Vec u32) (i : usize) : nat = admit ()
+
+(** [loops::list_mem]: decreases clause
+    Source: 'src/loops.rs', lines 66:0-75:1 *)
+unfold let list_mem_loop_decreases (x : u32) (ls : list_t u32) : nat = admit ()
+
+(** [loops::list_nth_mut_loop]: decreases clause
+    Source: 'src/loops.rs', lines 78:0-88:1 *)
+unfold
+let list_nth_mut_loop_loop_decreases (t : Type0) (ls : list_t t) (i : u32) :
+  nat =
+  admit ()
+
+(** [loops::list_nth_shared_loop]: decreases clause
+    Source: 'src/loops.rs', lines 91:0-101:1 *)
+unfold
+let list_nth_shared_loop_loop_decreases (t : Type0) (ls : list_t t) (i : u32) :
+  nat =
+  admit ()
+
+(** [loops::get_elem_mut]: decreases clause
+    Source: 'src/loops.rs', lines 103:0-117:1 *)
+unfold
+let get_elem_mut_loop_decreases (x : usize) (ls : list_t usize) : nat =
+  admit ()
+
+(** [loops::get_elem_shared]: decreases clause
+    Source: 'src/loops.rs', lines 119:0-133:1 *)
+unfold
+let get_elem_shared_loop_decreases (x : usize) (ls : list_t usize) : nat =
+  admit ()
+
+(** [loops::list_nth_mut_loop_with_id]: decreases clause
+    Source: 'src/loops.rs', lines 144:0-155:1 *)
+unfold
+let list_nth_mut_loop_with_id_loop_decreases (t : Type0) (i : u32)
+  (ls : list_t t) : nat =
+  admit ()
+
+(** [loops::list_nth_shared_loop_with_id]: decreases clause
+    Source: 'src/loops.rs', lines 158:0-169:1 *)
+unfold
+let list_nth_shared_loop_with_id_loop_decreases (t : Type0) (i : u32)
+  (ls : list_t t) : nat =
+  admit ()
+
+(** [loops::list_nth_mut_loop_pair]: decreases clause
+    Source: 'src/loops.rs', lines 174:0-195:1 *)
+unfold
+let list_nth_mut_loop_pair_loop_decreases (t : Type0) (ls0 : list_t t)
+  (ls1 : list_t t) (i : u32) : nat =
+  admit ()
+
+(** [loops::list_nth_shared_loop_pair]: decreases clause
+    Source: 'src/loops.rs', lines 198:0-219:1 *)
+unfold
+let list_nth_shared_loop_pair_loop_decreases (t : Type0) (ls0 : list_t t)
+  (ls1 : list_t t) (i : u32) : nat =
+  admit ()
+
+(** [loops::list_nth_mut_loop_pair_merge]: decreases clause
+    Source: 'src/loops.rs', lines 223:0-238:1 *)
+unfold
+let list_nth_mut_loop_pair_merge_loop_decreases (t : Type0) (ls0 : list_t t)
+  (ls1 : list_t t) (i : u32) : nat =
+  admit ()
+
+(** [loops::list_nth_shared_loop_pair_merge]: decreases clause
+    Source: 'src/loops.rs', lines 241:0-256:1 *)
+unfold
+let list_nth_shared_loop_pair_merge_loop_decreases (t : Type0) (ls0 : list_t t)
+  (ls1 : list_t t) (i : u32) : nat =
+  admit ()
+
+(** [loops::list_nth_mut_shared_loop_pair]: decreases clause
+    Source: 'src/loops.rs', lines 259:0-274:1 *)
+unfold
+let list_nth_mut_shared_loop_pair_loop_decreases (t : Type0) (ls0 : list_t t)
+  (ls1 : list_t t) (i : u32) : nat =
+  admit ()
+
+(** [loops::list_nth_mut_shared_loop_pair_merge]: decreases clause
+    Source: 'src/loops.rs', lines 278:0-293:1 *)
+unfold
+let list_nth_mut_shared_loop_pair_merge_loop_decreases (t : Type0)
+  (ls0 : list_t t) (ls1 : list_t t) (i : u32) : nat =
+  admit ()
+
+(** [loops::list_nth_shared_mut_loop_pair]: decreases clause
+    Source: 'src/loops.rs', lines 297:0-312:1 *)
+unfold
+let list_nth_shared_mut_loop_pair_loop_decreases (t : Type0) (ls0 : list_t t)
+  (ls1 : list_t t) (i : u32) : nat =
+  admit ()
+
+(** [loops::list_nth_shared_mut_loop_pair_merge]: decreases clause
+    Source: 'src/loops.rs', lines 316:0-331:1 *)
+unfold
+let list_nth_shared_mut_loop_pair_merge_loop_decreases (t : Type0)
+  (ls0 : list_t t) (ls1 : list_t t) (i : u32) : nat =
+  admit ()
+
diff --git a/tests/fstar-split/misc/Loops.Clauses.fst b/tests/fstar-split/misc/Loops.Clauses.fst
new file mode 100644
index 00000000..75194437
--- /dev/null
+++ b/tests/fstar-split/misc/Loops.Clauses.fst
@@ -0,0 +1,107 @@
+(** [loops]: templates for the decreases clauses *)
+module Loops.Clauses
+open Primitives
+open Loops.Types
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [loops::sum]: decreases clause *)
+unfold let sum_loop_decreases (max : u32) (i : u32) (s : u32) : nat =
+  if i <= max then max - i else 0
+
+(** [loops::sum_with_mut_borrows]: decreases clause *)
+unfold
+let sum_with_mut_borrows_loop_decreases (max : u32) (mi : u32) (ms : u32) : nat =
+  if max >= mi then max - mi else 0
+
+(** [loops::sum_with_shared_borrows]: decreases clause *)
+unfold
+let sum_with_shared_borrows_loop_decreases (max : u32) (i : u32) (s : u32) : nat =
+  if max >= i then max - i else 0
+
+(** [loops::clear]: decreases clause *)
+unfold let clear_loop_decreases (v : alloc_vec_Vec u32) (i : usize) : nat =
+  if i <= List.Tot.length v then List.Tot.length v - i else 0
+
+(** [loops::list_mem]: decreases clause *)
+unfold let list_mem_loop_decreases (i : u32) (ls : list_t u32) : list_t u32 =
+  ls
+
+(** [loops::list_nth_mut_loop]: decreases clause *)
+unfold
+let list_nth_mut_loop_loop_decreases (t : Type0) (ls : list_t t) (i : u32) : nat =
+  i
+
+(** [loops::list_nth_shared_loop]: decreases clause *)
+unfold
+let list_nth_shared_loop_loop_decreases (t : Type0) (ls : list_t t) (i : u32) : list_t t =
+  ls
+
+(** [loops::get_elem_mut]: decreases clause *)
+unfold
+let get_elem_mut_loop_decreases (x : usize) (ls : list_t usize) : list_t usize = ls
+
+(** [loops::get_elem_shared]: decreases clause *)
+unfold
+let get_elem_shared_loop_decreases (x : usize) (ls : list_t usize) : list_t usize =
+  ls
+
+(** [loops::list_nth_mut_loop_with_id]: decreases clause *)
+unfold
+let list_nth_mut_loop_with_id_loop_decreases (t : Type0) (i : u32) (ls : list_t t) :
+  list_t t =
+  ls
+
+(** [loops::list_nth_shared_loop_with_id]: decreases clause *)
+unfold
+let list_nth_shared_loop_with_id_loop_decreases (t : Type0) (i : u32)
+  (ls : list_t t) : list_t t =
+  ls
+
+(** [loops::list_nth_mut_loop_pair]: decreases clause *)
+unfold
+let list_nth_mut_loop_pair_loop_decreases (t : Type0) (l : list_t t) (l0 : list_t t)
+  (i : u32) : nat =
+  i
+
+(** [loops::list_nth_shared_loop_pair]: decreases clause *)
+unfold
+let list_nth_shared_loop_pair_loop_decreases (t : Type0) (l : list_t t)
+  (l0 : list_t t) (i : u32) : list_t t =
+  l
+
+(** [loops::list_nth_mut_loop_pair_merge]: decreases clause *)
+unfold
+let list_nth_mut_loop_pair_merge_loop_decreases (t : Type0) (l : list_t t)
+  (l0 : list_t t) (i : u32) : nat =
+  i
+
+(** [loops::list_nth_shared_loop_pair_merge]: decreases clause *)
+unfold
+let list_nth_shared_loop_pair_merge_loop_decreases (t : Type0) (l : list_t t)
+  (l0 : list_t t) (i : u32) : list_t t =
+  l
+
+(** [loops::list_nth_mut_shared_loop_pair]: decreases clause *)
+unfold
+let list_nth_mut_shared_loop_pair_loop_decreases (t : Type0) (l : list_t t)
+  (l0 : list_t t) (i : u32) : list_t t =
+  l
+
+(** [loops::list_nth_mut_shared_loop_pair_merge]: decreases clause *)
+unfold
+let list_nth_mut_shared_loop_pair_merge_loop_decreases (t : Type0) (l : list_t t)
+  (l0 : list_t t) (i : u32) : list_t t =
+  l
+
+(** [loops::list_nth_shared_mut_loop_pair]: decreases clause *)
+unfold
+let list_nth_shared_mut_loop_pair_loop_decreases (t : Type0) (l : list_t t)
+  (l0 : list_t t) (i : u32) : list_t t =
+  l
+
+(** [loops::list_nth_shared_mut_loop_pair_merge]: decreases clause *)
+unfold
+let list_nth_shared_mut_loop_pair_merge_loop_decreases (t : Type0) (l : list_t t)
+  (l0 : list_t t) (i : u32) : list_t t =
+  l
diff --git a/tests/fstar-split/misc/Loops.Funs.fst b/tests/fstar-split/misc/Loops.Funs.fst
new file mode 100644
index 00000000..3168fddb
--- /dev/null
+++ b/tests/fstar-split/misc/Loops.Funs.fst
@@ -0,0 +1,734 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [loops]: function definitions *)
+module Loops.Funs
+open Primitives
+include Loops.Types
+include Loops.Clauses
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [loops::sum]: loop 0: forward function
+    Source: 'src/loops.rs', lines 4:0-14:1 *)
+let rec sum_loop
+  (max : u32) (i : u32) (s : u32) :
+  Tot (result u32) (decreases (sum_loop_decreases max i s))
+  =
+  if i < max
+  then let* s1 = u32_add s i in let* i1 = u32_add i 1 in sum_loop max i1 s1
+  else u32_mul s 2
+
+(** [loops::sum]: forward function
+    Source: 'src/loops.rs', lines 4:0-4:27 *)
+let sum (max : u32) : result u32 =
+  sum_loop max 0 0
+
+(** [loops::sum_with_mut_borrows]: loop 0: forward function
+    Source: 'src/loops.rs', lines 19:0-31:1 *)
+let rec sum_with_mut_borrows_loop
+  (max : u32) (mi : u32) (ms : u32) :
+  Tot (result u32) (decreases (sum_with_mut_borrows_loop_decreases max mi ms))
+  =
+  if mi < max
+  then
+    let* ms1 = u32_add ms mi in
+    let* mi1 = u32_add mi 1 in
+    sum_with_mut_borrows_loop max mi1 ms1
+  else u32_mul ms 2
+
+(** [loops::sum_with_mut_borrows]: forward function
+    Source: 'src/loops.rs', lines 19:0-19:44 *)
+let sum_with_mut_borrows (max : u32) : result u32 =
+  sum_with_mut_borrows_loop max 0 0
+
+(** [loops::sum_with_shared_borrows]: loop 0: forward function
+    Source: 'src/loops.rs', lines 34:0-48:1 *)
+let rec sum_with_shared_borrows_loop
+  (max : u32) (i : u32) (s : u32) :
+  Tot (result u32) (decreases (sum_with_shared_borrows_loop_decreases max i s))
+  =
+  if i < max
+  then
+    let* i1 = u32_add i 1 in
+    let* s1 = u32_add s i1 in
+    sum_with_shared_borrows_loop max i1 s1
+  else u32_mul s 2
+
+(** [loops::sum_with_shared_borrows]: forward function
+    Source: 'src/loops.rs', lines 34:0-34:47 *)
+let sum_with_shared_borrows (max : u32) : result u32 =
+  sum_with_shared_borrows_loop max 0 0
+
+(** [loops::clear]: loop 0: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/loops.rs', lines 52:0-58:1 *)
+let rec clear_loop
+  (v : alloc_vec_Vec u32) (i : usize) :
+  Tot (result (alloc_vec_Vec u32)) (decreases (clear_loop_decreases v i))
+  =
+  let i1 = alloc_vec_Vec_len u32 v in
+  if i < i1
+  then
+    let* i2 = usize_add i 1 in
+    let* v1 =
+      alloc_vec_Vec_index_mut_back u32 usize
+        (core_slice_index_SliceIndexUsizeSliceTInst u32) v i 0 in
+    clear_loop v1 i2
+  else Return v
+
+(** [loops::clear]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/loops.rs', lines 52:0-52:30 *)
+let clear (v : alloc_vec_Vec u32) : result (alloc_vec_Vec u32) =
+  clear_loop v 0
+
+(** [loops::list_mem]: loop 0: forward function
+    Source: 'src/loops.rs', lines 66:0-75:1 *)
+let rec list_mem_loop
+  (x : u32) (ls : list_t u32) :
+  Tot (result bool) (decreases (list_mem_loop_decreases x ls))
+  =
+  begin match ls with
+  | List_Cons y tl -> if y = x then Return true else list_mem_loop x tl
+  | List_Nil -> Return false
+  end
+
+(** [loops::list_mem]: forward function
+    Source: 'src/loops.rs', lines 66:0-66:52 *)
+let list_mem (x : u32) (ls : list_t u32) : result bool =
+  list_mem_loop x ls
+
+(** [loops::list_nth_mut_loop]: loop 0: forward function
+    Source: 'src/loops.rs', lines 78:0-88:1 *)
+let rec list_nth_mut_loop_loop
+  (t : Type0) (ls : list_t t) (i : u32) :
+  Tot (result t) (decreases (list_nth_mut_loop_loop_decreases t ls i))
+  =
+  begin match ls with
+  | List_Cons x tl ->
+    if i = 0
+    then Return x
+    else let* i1 = u32_sub i 1 in list_nth_mut_loop_loop t tl i1
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_mut_loop]: forward function
+    Source: 'src/loops.rs', lines 78:0-78:71 *)
+let list_nth_mut_loop (t : Type0) (ls : list_t t) (i : u32) : result t =
+  list_nth_mut_loop_loop t ls i
+
+(** [loops::list_nth_mut_loop]: loop 0: backward function 0
+    Source: 'src/loops.rs', lines 78:0-88:1 *)
+let rec list_nth_mut_loop_loop_back
+  (t : Type0) (ls : list_t t) (i : u32) (ret : t) :
+  Tot (result (list_t t)) (decreases (list_nth_mut_loop_loop_decreases t ls i))
+  =
+  begin match ls with
+  | List_Cons x tl ->
+    if i = 0
+    then Return (List_Cons ret tl)
+    else
+      let* i1 = u32_sub i 1 in
+      let* tl1 = list_nth_mut_loop_loop_back t tl i1 ret in
+      Return (List_Cons x tl1)
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_mut_loop]: backward function 0
+    Source: 'src/loops.rs', lines 78:0-78:71 *)
+let list_nth_mut_loop_back
+  (t : Type0) (ls : list_t t) (i : u32) (ret : t) : result (list_t t) =
+  list_nth_mut_loop_loop_back t ls i ret
+
+(** [loops::list_nth_shared_loop]: loop 0: forward function
+    Source: 'src/loops.rs', lines 91:0-101:1 *)
+let rec list_nth_shared_loop_loop
+  (t : Type0) (ls : list_t t) (i : u32) :
+  Tot (result t) (decreases (list_nth_shared_loop_loop_decreases t ls i))
+  =
+  begin match ls with
+  | List_Cons x tl ->
+    if i = 0
+    then Return x
+    else let* i1 = u32_sub i 1 in list_nth_shared_loop_loop t tl i1
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_shared_loop]: forward function
+    Source: 'src/loops.rs', lines 91:0-91:66 *)
+let list_nth_shared_loop (t : Type0) (ls : list_t t) (i : u32) : result t =
+  list_nth_shared_loop_loop t ls i
+
+(** [loops::get_elem_mut]: loop 0: forward function
+    Source: 'src/loops.rs', lines 103:0-117:1 *)
+let rec get_elem_mut_loop
+  (x : usize) (ls : list_t usize) :
+  Tot (result usize) (decreases (get_elem_mut_loop_decreases x ls))
+  =
+  begin match ls with
+  | List_Cons y tl -> if y = x then Return y else get_elem_mut_loop x tl
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::get_elem_mut]: forward function
+    Source: 'src/loops.rs', lines 103:0-103:73 *)
+let get_elem_mut
+  (slots : alloc_vec_Vec (list_t usize)) (x : usize) : result usize =
+  let* l =
+    alloc_vec_Vec_index_mut (list_t usize) usize
+      (core_slice_index_SliceIndexUsizeSliceTInst (list_t usize)) slots 0 in
+  get_elem_mut_loop x l
+
+(** [loops::get_elem_mut]: loop 0: backward function 0
+    Source: 'src/loops.rs', lines 103:0-117:1 *)
+let rec get_elem_mut_loop_back
+  (x : usize) (ls : list_t usize) (ret : usize) :
+  Tot (result (list_t usize)) (decreases (get_elem_mut_loop_decreases x ls))
+  =
+  begin match ls with
+  | List_Cons y tl ->
+    if y = x
+    then Return (List_Cons ret tl)
+    else let* tl1 = get_elem_mut_loop_back x tl ret in Return (List_Cons y tl1)
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::get_elem_mut]: backward function 0
+    Source: 'src/loops.rs', lines 103:0-103:73 *)
+let get_elem_mut_back
+  (slots : alloc_vec_Vec (list_t usize)) (x : usize) (ret : usize) :
+  result (alloc_vec_Vec (list_t usize))
+  =
+  let* l =
+    alloc_vec_Vec_index_mut (list_t usize) usize
+      (core_slice_index_SliceIndexUsizeSliceTInst (list_t usize)) slots 0 in
+  let* l1 = get_elem_mut_loop_back x l ret in
+  alloc_vec_Vec_index_mut_back (list_t usize) usize
+    (core_slice_index_SliceIndexUsizeSliceTInst (list_t usize)) slots 0 l1
+
+(** [loops::get_elem_shared]: loop 0: forward function
+    Source: 'src/loops.rs', lines 119:0-133:1 *)
+let rec get_elem_shared_loop
+  (x : usize) (ls : list_t usize) :
+  Tot (result usize) (decreases (get_elem_shared_loop_decreases x ls))
+  =
+  begin match ls with
+  | List_Cons y tl -> if y = x then Return y else get_elem_shared_loop x tl
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::get_elem_shared]: forward function
+    Source: 'src/loops.rs', lines 119:0-119:68 *)
+let get_elem_shared
+  (slots : alloc_vec_Vec (list_t usize)) (x : usize) : result usize =
+  let* l =
+    alloc_vec_Vec_index (list_t usize) usize
+      (core_slice_index_SliceIndexUsizeSliceTInst (list_t usize)) slots 0 in
+  get_elem_shared_loop x l
+
+(** [loops::id_mut]: forward function
+    Source: 'src/loops.rs', lines 135:0-135:50 *)
+let id_mut (t : Type0) (ls : list_t t) : result (list_t t) =
+  Return ls
+
+(** [loops::id_mut]: backward function 0
+    Source: 'src/loops.rs', lines 135:0-135:50 *)
+let id_mut_back
+  (t : Type0) (ls : list_t t) (ret : list_t t) : result (list_t t) =
+  Return ret
+
+(** [loops::id_shared]: forward function
+    Source: 'src/loops.rs', lines 139:0-139:45 *)
+let id_shared (t : Type0) (ls : list_t t) : result (list_t t) =
+  Return ls
+
+(** [loops::list_nth_mut_loop_with_id]: loop 0: forward function
+    Source: 'src/loops.rs', lines 144:0-155:1 *)
+let rec list_nth_mut_loop_with_id_loop
+  (t : Type0) (i : u32) (ls : list_t t) :
+  Tot (result t) (decreases (list_nth_mut_loop_with_id_loop_decreases t i ls))
+  =
+  begin match ls with
+  | List_Cons x tl ->
+    if i = 0
+    then Return x
+    else let* i1 = u32_sub i 1 in list_nth_mut_loop_with_id_loop t i1 tl
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_mut_loop_with_id]: forward function
+    Source: 'src/loops.rs', lines 144:0-144:75 *)
+let list_nth_mut_loop_with_id
+  (t : Type0) (ls : list_t t) (i : u32) : result t =
+  let* ls1 = id_mut t ls in list_nth_mut_loop_with_id_loop t i ls1
+
+(** [loops::list_nth_mut_loop_with_id]: loop 0: backward function 0
+    Source: 'src/loops.rs', lines 144:0-155:1 *)
+let rec list_nth_mut_loop_with_id_loop_back
+  (t : Type0) (i : u32) (ls : list_t t) (ret : t) :
+  Tot (result (list_t t))
+  (decreases (list_nth_mut_loop_with_id_loop_decreases t i ls))
+  =
+  begin match ls with
+  | List_Cons x tl ->
+    if i = 0
+    then Return (List_Cons ret tl)
+    else
+      let* i1 = u32_sub i 1 in
+      let* tl1 = list_nth_mut_loop_with_id_loop_back t i1 tl ret in
+      Return (List_Cons x tl1)
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_mut_loop_with_id]: backward function 0
+    Source: 'src/loops.rs', lines 144:0-144:75 *)
+let list_nth_mut_loop_with_id_back
+  (t : Type0) (ls : list_t t) (i : u32) (ret : t) : result (list_t t) =
+  let* ls1 = id_mut t ls in
+  let* l = list_nth_mut_loop_with_id_loop_back t i ls1 ret in
+  id_mut_back t ls l
+
+(** [loops::list_nth_shared_loop_with_id]: loop 0: forward function
+    Source: 'src/loops.rs', lines 158:0-169:1 *)
+let rec list_nth_shared_loop_with_id_loop
+  (t : Type0) (i : u32) (ls : list_t t) :
+  Tot (result t)
+  (decreases (list_nth_shared_loop_with_id_loop_decreases t i ls))
+  =
+  begin match ls with
+  | List_Cons x tl ->
+    if i = 0
+    then Return x
+    else let* i1 = u32_sub i 1 in list_nth_shared_loop_with_id_loop t i1 tl
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_shared_loop_with_id]: forward function
+    Source: 'src/loops.rs', lines 158:0-158:70 *)
+let list_nth_shared_loop_with_id
+  (t : Type0) (ls : list_t t) (i : u32) : result t =
+  let* ls1 = id_shared t ls in list_nth_shared_loop_with_id_loop t i ls1
+
+(** [loops::list_nth_mut_loop_pair]: loop 0: forward function
+    Source: 'src/loops.rs', lines 174:0-195:1 *)
+let rec list_nth_mut_loop_pair_loop
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
+  Tot (result (t & t))
+  (decreases (list_nth_mut_loop_pair_loop_decreases t ls0 ls1 i))
+  =
+  begin match ls0 with
+  | List_Cons x0 tl0 ->
+    begin match ls1 with
+    | List_Cons x1 tl1 ->
+      if i = 0
+      then Return (x0, x1)
+      else let* i1 = u32_sub i 1 in list_nth_mut_loop_pair_loop t tl0 tl1 i1
+    | List_Nil -> Fail Failure
+    end
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_mut_loop_pair]: forward function
+    Source: 'src/loops.rs', lines 174:0-178:27 *)
+let list_nth_mut_loop_pair
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) : result (t & t) =
+  list_nth_mut_loop_pair_loop t ls0 ls1 i
+
+(** [loops::list_nth_mut_loop_pair]: loop 0: backward function 0
+    Source: 'src/loops.rs', lines 174:0-195:1 *)
+let rec list_nth_mut_loop_pair_loop_back'a
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
+  Tot (result (list_t t))
+  (decreases (list_nth_mut_loop_pair_loop_decreases t ls0 ls1 i))
+  =
+  begin match ls0 with
+  | List_Cons x0 tl0 ->
+    begin match ls1 with
+    | List_Cons _ tl1 ->
+      if i = 0
+      then Return (List_Cons ret tl0)
+      else
+        let* i1 = u32_sub i 1 in
+        let* tl01 = list_nth_mut_loop_pair_loop_back'a t tl0 tl1 i1 ret in
+        Return (List_Cons x0 tl01)
+    | List_Nil -> Fail Failure
+    end
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_mut_loop_pair]: backward function 0
+    Source: 'src/loops.rs', lines 174:0-178:27 *)
+let list_nth_mut_loop_pair_back'a
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
+  result (list_t t)
+  =
+  list_nth_mut_loop_pair_loop_back'a t ls0 ls1 i ret
+
+(** [loops::list_nth_mut_loop_pair]: loop 0: backward function 1
+    Source: 'src/loops.rs', lines 174:0-195:1 *)
+let rec list_nth_mut_loop_pair_loop_back'b
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
+  Tot (result (list_t t))
+  (decreases (list_nth_mut_loop_pair_loop_decreases t ls0 ls1 i))
+  =
+  begin match ls0 with
+  | List_Cons _ tl0 ->
+    begin match ls1 with
+    | List_Cons x1 tl1 ->
+      if i = 0
+      then Return (List_Cons ret tl1)
+      else
+        let* i1 = u32_sub i 1 in
+        let* tl11 = list_nth_mut_loop_pair_loop_back'b t tl0 tl1 i1 ret in
+        Return (List_Cons x1 tl11)
+    | List_Nil -> Fail Failure
+    end
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_mut_loop_pair]: backward function 1
+    Source: 'src/loops.rs', lines 174:0-178:27 *)
+let list_nth_mut_loop_pair_back'b
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
+  result (list_t t)
+  =
+  list_nth_mut_loop_pair_loop_back'b t ls0 ls1 i ret
+
+(** [loops::list_nth_shared_loop_pair]: loop 0: forward function
+    Source: 'src/loops.rs', lines 198:0-219:1 *)
+let rec list_nth_shared_loop_pair_loop
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
+  Tot (result (t & t))
+  (decreases (list_nth_shared_loop_pair_loop_decreases t ls0 ls1 i))
+  =
+  begin match ls0 with
+  | List_Cons x0 tl0 ->
+    begin match ls1 with
+    | List_Cons x1 tl1 ->
+      if i = 0
+      then Return (x0, x1)
+      else let* i1 = u32_sub i 1 in list_nth_shared_loop_pair_loop t tl0 tl1 i1
+    | List_Nil -> Fail Failure
+    end
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_shared_loop_pair]: forward function
+    Source: 'src/loops.rs', lines 198:0-202:19 *)
+let list_nth_shared_loop_pair
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) : result (t & t) =
+  list_nth_shared_loop_pair_loop t ls0 ls1 i
+
+(** [loops::list_nth_mut_loop_pair_merge]: loop 0: forward function
+    Source: 'src/loops.rs', lines 223:0-238:1 *)
+let rec list_nth_mut_loop_pair_merge_loop
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
+  Tot (result (t & t))
+  (decreases (list_nth_mut_loop_pair_merge_loop_decreases t ls0 ls1 i))
+  =
+  begin match ls0 with
+  | List_Cons x0 tl0 ->
+    begin match ls1 with
+    | List_Cons x1 tl1 ->
+      if i = 0
+      then Return (x0, x1)
+      else
+        let* i1 = u32_sub i 1 in list_nth_mut_loop_pair_merge_loop t tl0 tl1 i1
+    | List_Nil -> Fail Failure
+    end
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_mut_loop_pair_merge]: forward function
+    Source: 'src/loops.rs', lines 223:0-227:27 *)
+let list_nth_mut_loop_pair_merge
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) : result (t & t) =
+  list_nth_mut_loop_pair_merge_loop t ls0 ls1 i
+
+(** [loops::list_nth_mut_loop_pair_merge]: loop 0: backward function 0
+    Source: 'src/loops.rs', lines 223:0-238:1 *)
+let rec list_nth_mut_loop_pair_merge_loop_back
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : (t & t)) :
+  Tot (result ((list_t t) & (list_t t)))
+  (decreases (list_nth_mut_loop_pair_merge_loop_decreases t ls0 ls1 i))
+  =
+  begin match ls0 with
+  | List_Cons x0 tl0 ->
+    begin match ls1 with
+    | List_Cons x1 tl1 ->
+      if i = 0
+      then let (x, x2) = ret in Return (List_Cons x tl0, List_Cons x2 tl1)
+      else
+        let* i1 = u32_sub i 1 in
+        let* (tl01, tl11) =
+          list_nth_mut_loop_pair_merge_loop_back t tl0 tl1 i1 ret in
+        Return (List_Cons x0 tl01, List_Cons x1 tl11)
+    | List_Nil -> Fail Failure
+    end
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_mut_loop_pair_merge]: backward function 0
+    Source: 'src/loops.rs', lines 223:0-227:27 *)
+let list_nth_mut_loop_pair_merge_back
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : (t & t)) :
+  result ((list_t t) & (list_t t))
+  =
+  list_nth_mut_loop_pair_merge_loop_back t ls0 ls1 i ret
+
+(** [loops::list_nth_shared_loop_pair_merge]: loop 0: forward function
+    Source: 'src/loops.rs', lines 241:0-256:1 *)
+let rec list_nth_shared_loop_pair_merge_loop
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
+  Tot (result (t & t))
+  (decreases (list_nth_shared_loop_pair_merge_loop_decreases t ls0 ls1 i))
+  =
+  begin match ls0 with
+  | List_Cons x0 tl0 ->
+    begin match ls1 with
+    | List_Cons x1 tl1 ->
+      if i = 0
+      then Return (x0, x1)
+      else
+        let* i1 = u32_sub i 1 in
+        list_nth_shared_loop_pair_merge_loop t tl0 tl1 i1
+    | List_Nil -> Fail Failure
+    end
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_shared_loop_pair_merge]: forward function
+    Source: 'src/loops.rs', lines 241:0-245:19 *)
+let list_nth_shared_loop_pair_merge
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) : result (t & t) =
+  list_nth_shared_loop_pair_merge_loop t ls0 ls1 i
+
+(** [loops::list_nth_mut_shared_loop_pair]: loop 0: forward function
+    Source: 'src/loops.rs', lines 259:0-274:1 *)
+let rec list_nth_mut_shared_loop_pair_loop
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
+  Tot (result (t & t))
+  (decreases (list_nth_mut_shared_loop_pair_loop_decreases t ls0 ls1 i))
+  =
+  begin match ls0 with
+  | List_Cons x0 tl0 ->
+    begin match ls1 with
+    | List_Cons x1 tl1 ->
+      if i = 0
+      then Return (x0, x1)
+      else
+        let* i1 = u32_sub i 1 in
+        list_nth_mut_shared_loop_pair_loop t tl0 tl1 i1
+    | List_Nil -> Fail Failure
+    end
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_mut_shared_loop_pair]: forward function
+    Source: 'src/loops.rs', lines 259:0-263:23 *)
+let list_nth_mut_shared_loop_pair
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) : result (t & t) =
+  list_nth_mut_shared_loop_pair_loop t ls0 ls1 i
+
+(** [loops::list_nth_mut_shared_loop_pair]: loop 0: backward function 0
+    Source: 'src/loops.rs', lines 259:0-274:1 *)
+let rec list_nth_mut_shared_loop_pair_loop_back
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
+  Tot (result (list_t t))
+  (decreases (list_nth_mut_shared_loop_pair_loop_decreases t ls0 ls1 i))
+  =
+  begin match ls0 with
+  | List_Cons x0 tl0 ->
+    begin match ls1 with
+    | List_Cons _ tl1 ->
+      if i = 0
+      then Return (List_Cons ret tl0)
+      else
+        let* i1 = u32_sub i 1 in
+        let* tl01 = list_nth_mut_shared_loop_pair_loop_back t tl0 tl1 i1 ret in
+        Return (List_Cons x0 tl01)
+    | List_Nil -> Fail Failure
+    end
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_mut_shared_loop_pair]: backward function 0
+    Source: 'src/loops.rs', lines 259:0-263:23 *)
+let list_nth_mut_shared_loop_pair_back
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
+  result (list_t t)
+  =
+  list_nth_mut_shared_loop_pair_loop_back t ls0 ls1 i ret
+
+(** [loops::list_nth_mut_shared_loop_pair_merge]: loop 0: forward function
+    Source: 'src/loops.rs', lines 278:0-293:1 *)
+let rec list_nth_mut_shared_loop_pair_merge_loop
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
+  Tot (result (t & t))
+  (decreases (list_nth_mut_shared_loop_pair_merge_loop_decreases t ls0 ls1 i))
+  =
+  begin match ls0 with
+  | List_Cons x0 tl0 ->
+    begin match ls1 with
+    | List_Cons x1 tl1 ->
+      if i = 0
+      then Return (x0, x1)
+      else
+        let* i1 = u32_sub i 1 in
+        list_nth_mut_shared_loop_pair_merge_loop t tl0 tl1 i1
+    | List_Nil -> Fail Failure
+    end
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_mut_shared_loop_pair_merge]: forward function
+    Source: 'src/loops.rs', lines 278:0-282:23 *)
+let list_nth_mut_shared_loop_pair_merge
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) : result (t & t) =
+  list_nth_mut_shared_loop_pair_merge_loop t ls0 ls1 i
+
+(** [loops::list_nth_mut_shared_loop_pair_merge]: loop 0: backward function 0
+    Source: 'src/loops.rs', lines 278:0-293:1 *)
+let rec list_nth_mut_shared_loop_pair_merge_loop_back
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
+  Tot (result (list_t t))
+  (decreases (list_nth_mut_shared_loop_pair_merge_loop_decreases t ls0 ls1 i))
+  =
+  begin match ls0 with
+  | List_Cons x0 tl0 ->
+    begin match ls1 with
+    | List_Cons _ tl1 ->
+      if i = 0
+      then Return (List_Cons ret tl0)
+      else
+        let* i1 = u32_sub i 1 in
+        let* tl01 =
+          list_nth_mut_shared_loop_pair_merge_loop_back t tl0 tl1 i1 ret in
+        Return (List_Cons x0 tl01)
+    | List_Nil -> Fail Failure
+    end
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_mut_shared_loop_pair_merge]: backward function 0
+    Source: 'src/loops.rs', lines 278:0-282:23 *)
+let list_nth_mut_shared_loop_pair_merge_back
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
+  result (list_t t)
+  =
+  list_nth_mut_shared_loop_pair_merge_loop_back t ls0 ls1 i ret
+
+(** [loops::list_nth_shared_mut_loop_pair]: loop 0: forward function
+    Source: 'src/loops.rs', lines 297:0-312:1 *)
+let rec list_nth_shared_mut_loop_pair_loop
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
+  Tot (result (t & t))
+  (decreases (list_nth_shared_mut_loop_pair_loop_decreases t ls0 ls1 i))
+  =
+  begin match ls0 with
+  | List_Cons x0 tl0 ->
+    begin match ls1 with
+    | List_Cons x1 tl1 ->
+      if i = 0
+      then Return (x0, x1)
+      else
+        let* i1 = u32_sub i 1 in
+        list_nth_shared_mut_loop_pair_loop t tl0 tl1 i1
+    | List_Nil -> Fail Failure
+    end
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_shared_mut_loop_pair]: forward function
+    Source: 'src/loops.rs', lines 297:0-301:23 *)
+let list_nth_shared_mut_loop_pair
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) : result (t & t) =
+  list_nth_shared_mut_loop_pair_loop t ls0 ls1 i
+
+(** [loops::list_nth_shared_mut_loop_pair]: loop 0: backward function 1
+    Source: 'src/loops.rs', lines 297:0-312:1 *)
+let rec list_nth_shared_mut_loop_pair_loop_back
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
+  Tot (result (list_t t))
+  (decreases (list_nth_shared_mut_loop_pair_loop_decreases t ls0 ls1 i))
+  =
+  begin match ls0 with
+  | List_Cons _ tl0 ->
+    begin match ls1 with
+    | List_Cons x1 tl1 ->
+      if i = 0
+      then Return (List_Cons ret tl1)
+      else
+        let* i1 = u32_sub i 1 in
+        let* tl11 = list_nth_shared_mut_loop_pair_loop_back t tl0 tl1 i1 ret in
+        Return (List_Cons x1 tl11)
+    | List_Nil -> Fail Failure
+    end
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_shared_mut_loop_pair]: backward function 1
+    Source: 'src/loops.rs', lines 297:0-301:23 *)
+let list_nth_shared_mut_loop_pair_back
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
+  result (list_t t)
+  =
+  list_nth_shared_mut_loop_pair_loop_back t ls0 ls1 i ret
+
+(** [loops::list_nth_shared_mut_loop_pair_merge]: loop 0: forward function
+    Source: 'src/loops.rs', lines 316:0-331:1 *)
+let rec list_nth_shared_mut_loop_pair_merge_loop
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
+  Tot (result (t & t))
+  (decreases (list_nth_shared_mut_loop_pair_merge_loop_decreases t ls0 ls1 i))
+  =
+  begin match ls0 with
+  | List_Cons x0 tl0 ->
+    begin match ls1 with
+    | List_Cons x1 tl1 ->
+      if i = 0
+      then Return (x0, x1)
+      else
+        let* i1 = u32_sub i 1 in
+        list_nth_shared_mut_loop_pair_merge_loop t tl0 tl1 i1
+    | List_Nil -> Fail Failure
+    end
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_shared_mut_loop_pair_merge]: forward function
+    Source: 'src/loops.rs', lines 316:0-320:23 *)
+let list_nth_shared_mut_loop_pair_merge
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) : result (t & t) =
+  list_nth_shared_mut_loop_pair_merge_loop t ls0 ls1 i
+
+(** [loops::list_nth_shared_mut_loop_pair_merge]: loop 0: backward function 0
+    Source: 'src/loops.rs', lines 316:0-331:1 *)
+let rec list_nth_shared_mut_loop_pair_merge_loop_back
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
+  Tot (result (list_t t))
+  (decreases (list_nth_shared_mut_loop_pair_merge_loop_decreases t ls0 ls1 i))
+  =
+  begin match ls0 with
+  | List_Cons _ tl0 ->
+    begin match ls1 with
+    | List_Cons x1 tl1 ->
+      if i = 0
+      then Return (List_Cons ret tl1)
+      else
+        let* i1 = u32_sub i 1 in
+        let* tl11 =
+          list_nth_shared_mut_loop_pair_merge_loop_back t tl0 tl1 i1 ret in
+        Return (List_Cons x1 tl11)
+    | List_Nil -> Fail Failure
+    end
+  | List_Nil -> Fail Failure
+  end
+
+(** [loops::list_nth_shared_mut_loop_pair_merge]: backward function 0
+    Source: 'src/loops.rs', lines 316:0-320:23 *)
+let list_nth_shared_mut_loop_pair_merge_back
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
+  result (list_t t)
+  =
+  list_nth_shared_mut_loop_pair_merge_loop_back t ls0 ls1 i ret
+
diff --git a/tests/fstar-split/misc/Loops.Types.fst b/tests/fstar-split/misc/Loops.Types.fst
new file mode 100644
index 00000000..8aa38290
--- /dev/null
+++ b/tests/fstar-split/misc/Loops.Types.fst
@@ -0,0 +1,13 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [loops]: type definitions *)
+module Loops.Types
+open Primitives
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [loops::List]
+    Source: 'src/loops.rs', lines 60:0-60:16 *)
+type list_t (t : Type0) =
+| List_Cons : t -> list_t t -> list_t t
+| List_Nil : list_t t
+
diff --git a/tests/fstar-split/misc/Paper.fst b/tests/fstar-split/misc/Paper.fst
new file mode 100644
index 00000000..2dc804de
--- /dev/null
+++ b/tests/fstar-split/misc/Paper.fst
@@ -0,0 +1,110 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [paper] *)
+module Paper
+open Primitives
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [paper::ref_incr]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/paper.rs', lines 4:0-4:28 *)
+let ref_incr (x : i32) : result i32 =
+  i32_add x 1
+
+(** [paper::test_incr]: forward function
+    Source: 'src/paper.rs', lines 8:0-8:18 *)
+let test_incr : result unit =
+  let* x = ref_incr 0 in if not (x = 1) then Fail Failure else Return ()
+
+(** Unit test for [paper::test_incr] *)
+let _ = assert_norm (test_incr = Return ())
+
+(** [paper::choose]: forward function
+    Source: 'src/paper.rs', lines 15:0-15:70 *)
+let choose (t : Type0) (b : bool) (x : t) (y : t) : result t =
+  if b then Return x else Return y
+
+(** [paper::choose]: backward function 0
+    Source: 'src/paper.rs', lines 15:0-15:70 *)
+let choose_back
+  (t : Type0) (b : bool) (x : t) (y : t) (ret : t) : result (t & t) =
+  if b then Return (ret, y) else Return (x, ret)
+
+(** [paper::test_choose]: forward function
+    Source: 'src/paper.rs', lines 23:0-23:20 *)
+let test_choose : result unit =
+  let* z = choose i32 true 0 0 in
+  let* z1 = i32_add z 1 in
+  if not (z1 = 1)
+  then Fail Failure
+  else
+    let* (x, y) = choose_back i32 true 0 0 z1 in
+    if not (x = 1)
+    then Fail Failure
+    else if not (y = 0) then Fail Failure else Return ()
+
+(** Unit test for [paper::test_choose] *)
+let _ = assert_norm (test_choose = Return ())
+
+(** [paper::List]
+    Source: 'src/paper.rs', lines 35:0-35:16 *)
+type list_t (t : Type0) =
+| List_Cons : t -> list_t t -> list_t t
+| List_Nil : list_t t
+
+(** [paper::list_nth_mut]: forward function
+    Source: 'src/paper.rs', lines 42:0-42:67 *)
+let rec list_nth_mut (t : Type0) (l : list_t t) (i : u32) : result t =
+  begin match l with
+  | List_Cons x tl ->
+    if i = 0 then Return x else let* i1 = u32_sub i 1 in list_nth_mut t tl i1
+  | List_Nil -> Fail Failure
+  end
+
+(** [paper::list_nth_mut]: backward function 0
+    Source: 'src/paper.rs', lines 42:0-42:67 *)
+let rec list_nth_mut_back
+  (t : Type0) (l : list_t t) (i : u32) (ret : t) : result (list_t t) =
+  begin match l with
+  | List_Cons x tl ->
+    if i = 0
+    then Return (List_Cons ret tl)
+    else
+      let* i1 = u32_sub i 1 in
+      let* tl1 = list_nth_mut_back t tl i1 ret in
+      Return (List_Cons x tl1)
+  | List_Nil -> Fail Failure
+  end
+
+(** [paper::sum]: forward function
+    Source: 'src/paper.rs', lines 57:0-57:32 *)
+let rec sum (l : list_t i32) : result i32 =
+  begin match l with
+  | List_Cons x tl -> let* i = sum tl in i32_add x i
+  | List_Nil -> Return 0
+  end
+
+(** [paper::test_nth]: forward function
+    Source: 'src/paper.rs', lines 68:0-68:17 *)
+let test_nth : result unit =
+  let l = List_Nil in
+  let l1 = List_Cons 3 l in
+  let l2 = List_Cons 2 l1 in
+  let* x = list_nth_mut i32 (List_Cons 1 l2) 2 in
+  let* x1 = i32_add x 1 in
+  let* l3 = list_nth_mut_back i32 (List_Cons 1 l2) 2 x1 in
+  let* i = sum l3 in
+  if not (i = 7) then Fail Failure else Return ()
+
+(** Unit test for [paper::test_nth] *)
+let _ = assert_norm (test_nth = Return ())
+
+(** [paper::call_choose]: forward function
+    Source: 'src/paper.rs', lines 76:0-76:44 *)
+let call_choose (p : (u32 & u32)) : result u32 =
+  let (px, py) = p in
+  let* pz = choose u32 true px py in
+  let* pz1 = u32_add pz 1 in
+  let* (px1, _) = choose_back u32 true px py pz1 in
+  Return px1
+
diff --git a/tests/fstar-split/misc/PoloniusList.fst b/tests/fstar-split/misc/PoloniusList.fst
new file mode 100644
index 00000000..8a8b7ae3
--- /dev/null
+++ b/tests/fstar-split/misc/PoloniusList.fst
@@ -0,0 +1,34 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [polonius_list] *)
+module PoloniusList
+open Primitives
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** [polonius_list::List]
+    Source: 'src/polonius_list.rs', lines 3:0-3:16 *)
+type list_t (t : Type0) =
+| List_Cons : t -> list_t t -> list_t t
+| List_Nil : list_t t
+
+(** [polonius_list::get_list_at_x]: forward function
+    Source: 'src/polonius_list.rs', lines 13:0-13:76 *)
+let rec get_list_at_x (ls : list_t u32) (x : u32) : result (list_t u32) =
+  begin match ls with
+  | List_Cons hd tl ->
+    if hd = x then Return (List_Cons hd tl) else get_list_at_x tl x
+  | List_Nil -> Return List_Nil
+  end
+
+(** [polonius_list::get_list_at_x]: backward function 0
+    Source: 'src/polonius_list.rs', lines 13:0-13:76 *)
+let rec get_list_at_x_back
+  (ls : list_t u32) (x : u32) (ret : list_t u32) : result (list_t u32) =
+  begin match ls with
+  | List_Cons hd tl ->
+    if hd = x
+    then Return ret
+    else let* tl1 = get_list_at_x_back tl x ret in Return (List_Cons hd tl1)
+  | List_Nil -> Return ret
+  end
+
diff --git a/tests/fstar-split/traits/Makefile b/tests/fstar-split/traits/Makefile
new file mode 100644
index 00000000..fa7d1f36
--- /dev/null
+++ b/tests/fstar-split/traits/Makefile
@@ -0,0 +1,49 @@
+# This file was automatically generated - modify ../Makefile.template instead
+INCLUDE_DIRS = .
+
+FSTAR_INCLUDES = $(addprefix --include ,$(INCLUDE_DIRS))
+
+FSTAR_HINTS ?= --use_hints --use_hint_hashes --record_hints
+
+FSTAR_OPTIONS = $(FSTAR_HINTS) \
+  --cache_checked_modules $(FSTAR_INCLUDES) --cmi \
+  --warn_error '+241@247+285-274' \
+
+FSTAR_EXE ?= fstar.exe
+FSTAR_NO_FLAGS = $(FSTAR_EXE) --already_cached 'Prims FStar LowStar Steel' --odir obj --cache_dir obj
+
+FSTAR = $(FSTAR_NO_FLAGS) $(FSTAR_OPTIONS)
+
+# The F* roots are used to compute the dependency graph, and generate the .depend file
+FSTAR_ROOTS ?= $(wildcard *.fst *.fsti)
+
+# Build all the files
+all: $(addprefix obj/,$(addsuffix .checked,$(FSTAR_ROOTS)))
+
+# This is the right way to ensure the .depend file always gets re-built.
+ifeq (,$(filter %-in,$(MAKECMDGOALS)))
+ifndef NODEPEND
+ifndef MAKE_RESTARTS
+.depend: .FORCE
+	$(FSTAR_NO_FLAGS) --dep full $(notdir $(FSTAR_ROOTS)) > $@
+
+.PHONY: .FORCE
+.FORCE:
+endif
+endif
+
+include .depend
+endif
+
+# For the interactive mode
+%.fst-in %.fsti-in:
+	@echo $(FSTAR_OPTIONS)
+
+# Generete the .checked files in batch mode
+%.checked:
+	$(FSTAR) $(FSTAR_OPTIONS) $< && \
+	touch -c $@
+
+.PHONY: clean
+clean:
+	rm -f obj/*
diff --git a/tests/fstar-split/traits/Primitives.fst b/tests/fstar-split/traits/Primitives.fst
new file mode 100644
index 00000000..a3ffbde4
--- /dev/null
+++ b/tests/fstar-split/traits/Primitives.fst
@@ -0,0 +1,884 @@
+/// This file lists primitive and assumed functions and types
+module Primitives
+open FStar.Mul
+open FStar.List.Tot
+
+#set-options "--z3rlimit 15 --fuel 0 --ifuel 1"
+
+(*** Utilities *)
+val list_update (#a : Type0) (ls : list a) (i : nat{i < length ls}) (x : a) :
+  ls':list a{
+    length ls' = length ls /\
+    index ls' i == x
+  }
+#push-options "--fuel 1"
+let rec list_update #a ls i x =
+  match ls with
+  | x' :: ls -> if i = 0 then x :: ls else x' :: list_update ls (i-1) x
+#pop-options
+
+(*** Result *)
+type error : Type0 =
+| Failure
+| OutOfFuel
+
+type result (a : Type0) : Type0 =
+| Return : v:a -> result a
+| Fail : e:error -> result a
+
+// Monadic return operator
+unfold let return (#a : Type0) (x : a) : result a = Return x
+
+// Monadic bind operator.
+// Allows to use the notation:
+// ```
+// let* x = y in
+// ...
+// ```
+unfold let (let*) (#a #b : Type0) (m: result a)
+  (f: (x:a) -> Pure (result b) (requires (m == Return x)) (ensures fun _ -> True)) :
+  result b =
+  match m with
+  | Return x -> f x
+  | Fail e   -> Fail e
+
+// Monadic assert(...)
+let massert (b:bool) : result unit = if b then Return () else Fail Failure
+
+// Normalize and unwrap a successful result (used for globals).
+let eval_global (#a : Type0) (x : result a{Return? (normalize_term x)}) : a = Return?.v x
+
+(*** Misc *)
+type char = FStar.Char.char
+type string = string
+
+let is_zero (n: nat) : bool = n = 0
+let decrease (n: nat{n > 0}) : nat = n - 1
+
+let core_mem_replace (a : Type0) (x : a) (y : a) : a = x
+let core_mem_replace_back (a : Type0) (x : a) (y : a) : a = y
+
+// We don't really use raw pointers for now
+type mut_raw_ptr (t : Type0) = { v : t }
+type const_raw_ptr (t : Type0) = { v : t }
+
+(*** Scalars *)
+/// Rem.: most of the following code was partially generated
+
+assume val size_numbits : pos
+
+// TODO: we could use FStar.Int.int_t and FStar.UInt.int_t
+
+let isize_min : int = -9223372036854775808 // TODO: should be opaque
+let isize_max : int = 9223372036854775807 // TODO: should be opaque
+let i8_min : int = -128
+let i8_max : int = 127
+let i16_min : int = -32768
+let i16_max : int = 32767
+let i32_min : int = -2147483648
+let i32_max : int = 2147483647
+let i64_min : int = -9223372036854775808
+let i64_max : int = 9223372036854775807
+let i128_min : int = -170141183460469231731687303715884105728
+let i128_max : int = 170141183460469231731687303715884105727
+let usize_min : int = 0
+let usize_max : int = 4294967295 // TODO: should be opaque
+let u8_min : int = 0
+let u8_max : int = 255
+let u16_min : int = 0
+let u16_max : int = 65535
+let u32_min : int = 0
+let u32_max : int = 4294967295
+let u64_min : int = 0
+let u64_max : int = 18446744073709551615
+let u128_min : int = 0
+let u128_max : int = 340282366920938463463374607431768211455
+
+type scalar_ty =
+| Isize
+| I8
+| I16
+| I32
+| I64
+| I128
+| Usize
+| U8
+| U16
+| U32
+| U64
+| U128
+
+let is_unsigned = function
+  | Isize | I8 | I16 | I32 | I64 | I128 -> false
+  | Usize | U8 | U16 | U32 | U64 | U128 -> true
+
+let scalar_min (ty : scalar_ty) : int =
+  match ty with
+  | Isize -> isize_min
+  | I8 -> i8_min
+  | I16 -> i16_min
+  | I32 -> i32_min
+  | I64 -> i64_min
+  | I128 -> i128_min
+  | Usize -> usize_min
+  | U8 -> u8_min
+  | U16 -> u16_min
+  | U32 -> u32_min
+  | U64 -> u64_min
+  | U128 -> u128_min
+
+let scalar_max (ty : scalar_ty) : int =
+  match ty with
+  | Isize -> isize_max
+  | I8 -> i8_max
+  | I16 -> i16_max
+  | I32 -> i32_max
+  | I64 -> i64_max
+  | I128 -> i128_max
+  | Usize -> usize_max
+  | U8 -> u8_max
+  | U16 -> u16_max
+  | U32 -> u32_max
+  | U64 -> u64_max
+  | U128 -> u128_max
+
+type scalar (ty : scalar_ty) : eqtype = x:int{scalar_min ty <= x && x <= scalar_max ty}
+
+let mk_scalar (ty : scalar_ty) (x : int) : result (scalar ty) =
+  if scalar_min ty <= x && scalar_max ty >= x then Return x else Fail Failure
+
+let scalar_neg (#ty : scalar_ty) (x : scalar ty) : result (scalar ty) = mk_scalar ty (-x)
+
+let scalar_div (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  if y <> 0 then mk_scalar ty (x / y) else Fail Failure
+
+/// The remainder operation
+let int_rem (x : int) (y : int{y <> 0}) : int =
+  if x >= 0 then (x % y) else -(x % y)
+
+(* Checking consistency with Rust *)
+let _ = assert_norm(int_rem 1 2 = 1)
+let _ = assert_norm(int_rem (-1) 2 = -1)
+let _ = assert_norm(int_rem 1 (-2) = 1)
+let _ = assert_norm(int_rem (-1) (-2) = -1)
+
+let scalar_rem (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  if y <> 0 then mk_scalar ty (int_rem x y) else Fail Failure
+
+let scalar_add (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  mk_scalar ty (x + y)
+
+let scalar_sub (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  mk_scalar ty (x - y)
+
+let scalar_mul (#ty : scalar_ty) (x : scalar ty) (y : scalar ty) : result (scalar ty) =
+  mk_scalar ty (x * y)
+
+let scalar_xor (#ty : scalar_ty)
+    (x : scalar ty) (y : scalar ty) : scalar ty =
+  match ty with
+  | U8 -> FStar.UInt.logxor #8 x y
+  | U16 -> FStar.UInt.logxor #16 x y
+  | U32 -> FStar.UInt.logxor #32 x y
+  | U64 -> FStar.UInt.logxor #64 x y
+  | U128 -> FStar.UInt.logxor #128 x y
+  | Usize -> admit() // TODO
+  | I8 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 8);
+    normalize_spec (scalar I8);
+    FStar.Int.logxor #8 x y
+  | I16 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 16);
+    normalize_spec (scalar I16);
+    FStar.Int.logxor #16 x y
+  | I32 -> FStar.Int.logxor #32 x y
+  | I64 -> FStar.Int.logxor #64 x y
+  | I128 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 128);
+    normalize_spec (scalar I128);
+    FStar.Int.logxor #128 x y
+  | Isize -> admit() // TODO
+
+let scalar_or (#ty : scalar_ty)
+    (x : scalar ty) (y : scalar ty) : scalar ty =
+  match ty with
+  | U8 -> FStar.UInt.logor #8 x y
+  | U16 -> FStar.UInt.logor #16 x y
+  | U32 -> FStar.UInt.logor #32 x y
+  | U64 -> FStar.UInt.logor #64 x y
+  | U128 -> FStar.UInt.logor #128 x y
+  | Usize -> admit() // TODO
+  | I8 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 8);
+    normalize_spec (scalar I8);
+    FStar.Int.logor #8 x y
+  | I16 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 16);
+    normalize_spec (scalar I16);
+    FStar.Int.logor #16 x y
+  | I32 -> FStar.Int.logor #32 x y
+  | I64 -> FStar.Int.logor #64 x y
+  | I128 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 128);
+    normalize_spec (scalar I128);
+    FStar.Int.logor #128 x y
+  | Isize -> admit() // TODO
+
+let scalar_and (#ty : scalar_ty)
+    (x : scalar ty) (y : scalar ty) : scalar ty =
+  match ty with
+  | U8 -> FStar.UInt.logand #8 x y
+  | U16 -> FStar.UInt.logand #16 x y
+  | U32 -> FStar.UInt.logand #32 x y
+  | U64 -> FStar.UInt.logand #64 x y
+  | U128 -> FStar.UInt.logand #128 x y
+  | Usize -> admit() // TODO
+  | I8 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 8);
+    normalize_spec (scalar I8);
+    FStar.Int.logand #8 x y
+  | I16 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 16);
+    normalize_spec (scalar I16);
+    FStar.Int.logand #16 x y
+  | I32 -> FStar.Int.logand #32 x y
+  | I64 -> FStar.Int.logand #64 x y
+  | I128 ->
+    // Encoding issues...
+    normalize_spec (FStar.Int.int_t 128);
+    normalize_spec (scalar I128);
+    FStar.Int.logand #128 x y
+  | Isize -> admit() // TODO
+
+// Shift left
+let scalar_shl (#ty0 #ty1 : scalar_ty)
+    (x : scalar ty0) (y : scalar ty1) : result (scalar ty0) =
+  admit()
+
+// Shift right
+let scalar_shr (#ty0 #ty1 : scalar_ty)
+    (x : scalar ty0) (y : scalar ty1) : result (scalar ty0) =
+  admit()
+
+(** Cast an integer from a [src_ty] to a [tgt_ty] *)
+// TODO: check the semantics of casts in Rust
+let scalar_cast (src_ty : scalar_ty) (tgt_ty : scalar_ty) (x : scalar src_ty) : result (scalar tgt_ty) =
+  mk_scalar tgt_ty x
+
+// This can't fail, but for now we make all casts faillible (easier for the translation)
+let scalar_cast_bool (tgt_ty : scalar_ty) (x : bool) : result (scalar tgt_ty) =
+  mk_scalar tgt_ty (if x then 1 else 0)
+
+/// The scalar types
+type isize : eqtype = scalar Isize
+type i8    : eqtype = scalar I8
+type i16   : eqtype = scalar I16
+type i32   : eqtype = scalar I32
+type i64   : eqtype = scalar I64
+type i128  : eqtype = scalar I128
+type usize : eqtype = scalar Usize
+type u8    : eqtype = scalar U8
+type u16   : eqtype = scalar U16
+type u32   : eqtype = scalar U32
+type u64   : eqtype = scalar U64
+type u128  : eqtype = scalar U128
+
+
+let core_isize_min : isize = isize_min
+let core_isize_max : isize = isize_max
+let core_i8_min    : i8 = i8_min
+let core_i8_max    : i8 = i8_max
+let core_i16_min   : i16 = i16_min
+let core_i16_max   : i16 = i16_max
+let core_i32_min   : i32 = i32_min
+let core_i32_max   : i32 = i32_max
+let core_i64_min   : i64 = i64_min
+let core_i64_max   : i64 = i64_max
+let core_i128_min  : i128 = i128_min
+let core_i128_max  : i128 = i128_max
+
+let core_usize_min : usize = usize_min
+let core_usize_max : usize = usize_max
+let core_u8_min    : u8 = u8_min
+let core_u8_max    : u8 = u8_max
+let core_u16_min   : u16 = u16_min
+let core_u16_max   : u16 = u16_max
+let core_u32_min   : u32 = u32_min
+let core_u32_max   : u32 = u32_max
+let core_u64_min   : u64 = u64_min
+let core_u64_max   : u64 = u64_max
+let core_u128_min  : u128 = u128_min
+let core_u128_max  : u128 = u128_max
+
+/// Negation
+let isize_neg = scalar_neg #Isize
+let i8_neg = scalar_neg #I8
+let i16_neg = scalar_neg #I16
+let i32_neg = scalar_neg #I32
+let i64_neg = scalar_neg #I64
+let i128_neg = scalar_neg #I128
+
+/// Division
+let isize_div = scalar_div #Isize
+let i8_div = scalar_div #I8
+let i16_div = scalar_div #I16
+let i32_div = scalar_div #I32
+let i64_div = scalar_div #I64
+let i128_div = scalar_div #I128
+let usize_div = scalar_div #Usize
+let u8_div = scalar_div #U8
+let u16_div = scalar_div #U16
+let u32_div = scalar_div #U32
+let u64_div = scalar_div #U64
+let u128_div = scalar_div #U128
+
+/// Remainder
+let isize_rem = scalar_rem #Isize
+let i8_rem = scalar_rem #I8
+let i16_rem = scalar_rem #I16
+let i32_rem = scalar_rem #I32
+let i64_rem = scalar_rem #I64
+let i128_rem = scalar_rem #I128
+let usize_rem = scalar_rem #Usize
+let u8_rem = scalar_rem #U8
+let u16_rem = scalar_rem #U16
+let u32_rem = scalar_rem #U32
+let u64_rem = scalar_rem #U64
+let u128_rem = scalar_rem #U128
+
+/// Addition
+let isize_add = scalar_add #Isize
+let i8_add = scalar_add #I8
+let i16_add = scalar_add #I16
+let i32_add = scalar_add #I32
+let i64_add = scalar_add #I64
+let i128_add = scalar_add #I128
+let usize_add = scalar_add #Usize
+let u8_add = scalar_add #U8
+let u16_add = scalar_add #U16
+let u32_add = scalar_add #U32
+let u64_add = scalar_add #U64
+let u128_add = scalar_add #U128
+
+/// Subtraction
+let isize_sub = scalar_sub #Isize
+let i8_sub = scalar_sub #I8
+let i16_sub = scalar_sub #I16
+let i32_sub = scalar_sub #I32
+let i64_sub = scalar_sub #I64
+let i128_sub = scalar_sub #I128
+let usize_sub = scalar_sub #Usize
+let u8_sub = scalar_sub #U8
+let u16_sub = scalar_sub #U16
+let u32_sub = scalar_sub #U32
+let u64_sub = scalar_sub #U64
+let u128_sub = scalar_sub #U128
+
+/// Multiplication
+let isize_mul = scalar_mul #Isize
+let i8_mul = scalar_mul #I8
+let i16_mul = scalar_mul #I16
+let i32_mul = scalar_mul #I32
+let i64_mul = scalar_mul #I64
+let i128_mul = scalar_mul #I128
+let usize_mul = scalar_mul #Usize
+let u8_mul = scalar_mul #U8
+let u16_mul = scalar_mul #U16
+let u32_mul = scalar_mul #U32
+let u64_mul = scalar_mul #U64
+let u128_mul = scalar_mul #U128
+
+/// Xor
+let u8_xor = scalar_xor #U8
+let u16_xor = scalar_xor #U16
+let u32_xor = scalar_xor #U32
+let u64_xor = scalar_xor #U64
+let u128_xor = scalar_xor #U128
+let usize_xor = scalar_xor #Usize
+let i8_xor = scalar_xor #I8
+let i16_xor = scalar_xor #I16
+let i32_xor = scalar_xor #I32
+let i64_xor = scalar_xor #I64
+let i128_xor = scalar_xor #I128
+let isize_xor = scalar_xor #Isize
+
+/// Or
+let u8_or = scalar_or #U8
+let u16_or = scalar_or #U16
+let u32_or = scalar_or #U32
+let u64_or = scalar_or #U64
+let u128_or = scalar_or #U128
+let usize_or = scalar_or #Usize
+let i8_or = scalar_or #I8
+let i16_or = scalar_or #I16
+let i32_or = scalar_or #I32
+let i64_or = scalar_or #I64
+let i128_or = scalar_or #I128
+let isize_or = scalar_or #Isize
+
+/// And
+let u8_and = scalar_and #U8
+let u16_and = scalar_and #U16
+let u32_and = scalar_and #U32
+let u64_and = scalar_and #U64
+let u128_and = scalar_and #U128
+let usize_and = scalar_and #Usize
+let i8_and = scalar_and #I8
+let i16_and = scalar_and #I16
+let i32_and = scalar_and #I32
+let i64_and = scalar_and #I64
+let i128_and = scalar_and #I128
+let isize_and = scalar_and #Isize
+
+/// Shift left
+let u8_shl #ty = scalar_shl #U8 #ty
+let u16_shl #ty = scalar_shl #U16 #ty
+let u32_shl #ty = scalar_shl #U32 #ty
+let u64_shl #ty = scalar_shl #U64 #ty
+let u128_shl #ty = scalar_shl #U128 #ty
+let usize_shl #ty = scalar_shl #Usize #ty
+let i8_shl #ty = scalar_shl #I8 #ty
+let i16_shl #ty = scalar_shl #I16 #ty
+let i32_shl #ty = scalar_shl #I32 #ty
+let i64_shl #ty = scalar_shl #I64 #ty
+let i128_shl #ty = scalar_shl #I128 #ty
+let isize_shl #ty = scalar_shl #Isize #ty
+
+/// Shift right
+let u8_shr #ty = scalar_shr #U8 #ty
+let u16_shr #ty = scalar_shr #U16 #ty
+let u32_shr #ty = scalar_shr #U32 #ty
+let u64_shr #ty = scalar_shr #U64 #ty
+let u128_shr #ty = scalar_shr #U128 #ty
+let usize_shr #ty = scalar_shr #Usize #ty
+let i8_shr #ty = scalar_shr #I8 #ty
+let i16_shr #ty = scalar_shr #I16 #ty
+let i32_shr #ty = scalar_shr #I32 #ty
+let i64_shr #ty = scalar_shr #I64 #ty
+let i128_shr #ty = scalar_shr #I128 #ty
+let isize_shr #ty = scalar_shr #Isize #ty
+
+(*** core::ops *)
+
+// Trait declaration: [core::ops::index::Index]
+noeq type core_ops_index_Index (self idx : Type0) = {
+  output : Type0;
+  index : self → idx → result output
+}
+
+// Trait declaration: [core::ops::index::IndexMut]
+noeq type core_ops_index_IndexMut (self idx : Type0) = {
+  indexInst : core_ops_index_Index self idx;
+  index_mut : self → idx → result indexInst.output;
+  index_mut_back : self → idx → indexInst.output → result self;
+}
+
+// Trait declaration [core::ops::deref::Deref]
+noeq type core_ops_deref_Deref (self : Type0) = {
+  target : Type0;
+  deref : self → result target;
+}
+
+// Trait declaration [core::ops::deref::DerefMut]
+noeq type core_ops_deref_DerefMut (self : Type0) = {
+  derefInst : core_ops_deref_Deref self;
+  deref_mut : self → result derefInst.target;
+  deref_mut_back : self → derefInst.target → result self;
+}
+
+type core_ops_range_Range (a : Type0) = {
+  start : a;
+  end_ : a;
+}
+
+(*** [alloc] *)
+
+let alloc_boxed_Box_deref (t : Type0) (x : t) : result t = Return x
+let alloc_boxed_Box_deref_mut (t : Type0) (x : t) : result t = Return x
+let alloc_boxed_Box_deref_mut_back (t : Type) (_ : t) (x : t) : result t = Return x
+
+// Trait instance
+let alloc_boxed_Box_coreopsDerefInst (self : Type0) : core_ops_deref_Deref self = {
+  target = self;
+  deref = alloc_boxed_Box_deref self;
+}
+
+// Trait instance
+let alloc_boxed_Box_coreopsDerefMutInst (self : Type0) : core_ops_deref_DerefMut self = {
+  derefInst = alloc_boxed_Box_coreopsDerefInst self;
+  deref_mut = alloc_boxed_Box_deref_mut self;
+  deref_mut_back = alloc_boxed_Box_deref_mut_back self;
+}
+
+(*** Array *)
+type array (a : Type0) (n : usize) = s:list a{length s = n}
+
+// We tried putting the normalize_term condition as a refinement on the list
+// but it didn't work. It works with the requires clause.
+let mk_array (a : Type0) (n : usize)
+  (l : list a) :
+  Pure (array a n)
+  (requires (normalize_term(FStar.List.Tot.length l) = n))
+  (ensures (fun _ -> True)) =
+  normalize_term_spec (FStar.List.Tot.length l);
+  l
+
+let array_index_usize (a : Type0) (n : usize) (x : array a n) (i : usize) : result a =
+  if i < length x then Return (index x i)
+  else Fail Failure
+
+let array_update_usize (a : Type0) (n : usize) (x : array a n) (i : usize) (nx : a) : result (array a n) =
+  if i < length x then Return (list_update x i nx)
+  else Fail Failure
+
+(*** Slice *)
+type slice (a : Type0) = s:list a{length s <= usize_max}
+
+let slice_len (a : Type0) (s : slice a) : usize = length s
+
+let slice_index_usize (a : Type0) (x : slice a) (i : usize) : result a =
+  if i < length x then Return (index x i)
+  else Fail Failure
+
+let slice_update_usize (a : Type0) (x : slice a) (i : usize) (nx : a) : result (slice a) =
+  if i < length x then Return (list_update x i nx)
+  else Fail Failure
+
+(*** Subslices *)
+
+let array_to_slice (a : Type0) (n : usize) (x : array a n) : result (slice a) = Return x
+let array_from_slice (a : Type0) (n : usize) (x : array a n) (s : slice a) : result (array a n) =
+  if length s = n then Return s
+  else Fail Failure
+
+// TODO: finish the definitions below (there lacks [List.drop] and [List.take] in the standard library *)
+let array_subslice (a : Type0) (n : usize) (x : array a n) (r : core_ops_range_Range usize) : result (slice a) =
+  admit()
+
+let array_update_subslice (a : Type0) (n : usize) (x : array a n) (r : core_ops_range_Range usize) (ns : slice a) : result (array a n) =
+  admit()
+
+let array_repeat (a : Type0) (n : usize) (x : a) : array a n =
+  admit()
+
+let slice_subslice (a : Type0) (x : slice a) (r : core_ops_range_Range usize) : result (slice a) =
+  admit()
+
+let slice_update_subslice (a : Type0) (x : slice a) (r : core_ops_range_Range usize) (ns : slice a) : result (slice a) =
+  admit()
+
+(*** Vector *)
+type alloc_vec_Vec (a : Type0) = v:list a{length v <= usize_max}
+
+let alloc_vec_Vec_new (a  : Type0) : alloc_vec_Vec a = assert_norm(length #a [] == 0); []
+let alloc_vec_Vec_len (a : Type0) (v : alloc_vec_Vec a) : usize = length v
+
+// Helper
+let alloc_vec_Vec_index_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) : result a =
+  if i < length v then Return (index v i) else Fail Failure
+// Helper
+let alloc_vec_Vec_update_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
+  if i < length v then Return (list_update v i x) else Fail Failure
+
+// The **forward** function shouldn't be used
+let alloc_vec_Vec_push_fwd (a  : Type0) (v : alloc_vec_Vec a) (x : a) : unit = ()
+let alloc_vec_Vec_push (a  : Type0) (v : alloc_vec_Vec a) (x : a) :
+  Pure (result (alloc_vec_Vec a))
+  (requires True)
+  (ensures (fun res ->
+    match res with
+    | Fail e -> e == Failure
+    | Return v' -> length v' = length v + 1)) =
+  if length v < usize_max then begin
+    (**) assert_norm(length [x] == 1);
+    (**) append_length v [x];
+    (**) assert(length (append v [x]) = length v + 1);
+    Return (append v [x])
+    end
+  else Fail Failure
+
+// The **forward** function shouldn't be used
+let alloc_vec_Vec_insert_fwd (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result unit =
+  if i < length v then Return () else Fail Failure
+let alloc_vec_Vec_insert (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
+  if i < length v then Return (list_update v i x) else Fail Failure
+
+// Trait declaration: [core::slice::index::private_slice_index::Sealed]
+type core_slice_index_private_slice_index_Sealed (self : Type0) = unit
+
+// Trait declaration: [core::slice::index::SliceIndex]
+noeq type core_slice_index_SliceIndex (self t : Type0) = {
+  sealedInst : core_slice_index_private_slice_index_Sealed self;
+  output : Type0;
+  get : self → t → result (option output);
+  get_mut : self → t → result (option output);
+  get_mut_back : self → t → option output → result t;
+  get_unchecked : self → const_raw_ptr t → result (const_raw_ptr output);
+  get_unchecked_mut : self → mut_raw_ptr t → result (mut_raw_ptr output);
+  index : self → t → result output;
+  index_mut : self → t → result output;
+  index_mut_back : self → t → output → result t;
+}
+
+// [core::slice::index::[T]::index]: forward function
+let core_slice_index_Slice_index
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (s : slice t) (i : idx) : result inst.output =
+  let* x = inst.get i s in
+  match x with
+  | None -> Fail Failure
+  | Some x -> Return x
+
+// [core::slice::index::Range:::get]: forward function
+let core_slice_index_RangeUsize_get (t : Type0) (i : core_ops_range_Range usize) (s : slice t) :
+  result (option (slice t)) =
+  admit () // TODO
+
+// [core::slice::index::Range::get_mut]: forward function
+let core_slice_index_RangeUsize_get_mut
+  (t : Type0) : core_ops_range_Range usize → slice t → result (option (slice t)) =
+  admit () // TODO
+
+// [core::slice::index::Range::get_mut]: backward function 0
+let core_slice_index_RangeUsize_get_mut_back
+  (t : Type0) :
+  core_ops_range_Range usize → slice t → option (slice t) → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::Range::get_unchecked]: forward function
+let core_slice_index_RangeUsize_get_unchecked
+  (t : Type0) :
+  core_ops_range_Range usize → const_raw_ptr (slice t) → result (const_raw_ptr (slice t)) =
+  // Don't know what the model should be - for now we always fail to make
+  // sure code which uses it fails
+  fun _ _ -> Fail Failure
+
+// [core::slice::index::Range::get_unchecked_mut]: forward function
+let core_slice_index_RangeUsize_get_unchecked_mut
+  (t : Type0) :
+  core_ops_range_Range usize → mut_raw_ptr (slice t) → result (mut_raw_ptr (slice t)) =
+  // Don't know what the model should be - for now we always fail to make
+  // sure code which uses it fails
+  fun _ _ -> Fail Failure
+
+// [core::slice::index::Range::index]: forward function
+let core_slice_index_RangeUsize_index
+  (t : Type0) : core_ops_range_Range usize → slice t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::Range::index_mut]: forward function
+let core_slice_index_RangeUsize_index_mut
+  (t : Type0) : core_ops_range_Range usize → slice t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::Range::index_mut]: backward function 0
+let core_slice_index_RangeUsize_index_mut_back
+  (t : Type0) : core_ops_range_Range usize → slice t → slice t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::[T]::index_mut]: forward function
+let core_slice_index_Slice_index_mut
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
+  slice t → idx → result inst.output =
+  admit () // 
+
+// [core::slice::index::[T]::index_mut]: backward function 0
+let core_slice_index_Slice_index_mut_back
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
+  slice t → idx → inst.output → result (slice t) =
+  admit () // TODO
+
+// [core::array::[T; N]::index]: forward function
+let core_array_Array_index
+  (t idx : Type0) (n : usize) (inst : core_ops_index_Index (slice t) idx)
+  (a : array t n) (i : idx) : result inst.output =
+  admit () // TODO
+
+// [core::array::[T; N]::index_mut]: forward function
+let core_array_Array_index_mut
+  (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
+  (a : array t n) (i : idx) : result inst.indexInst.output =
+  admit () // TODO
+
+// [core::array::[T; N]::index_mut]: backward function 0
+let core_array_Array_index_mut_back
+  (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
+  (a : array t n) (i : idx) (x : inst.indexInst.output) : result (array t n) =
+  admit () // TODO
+
+// Trait implementation: [core::slice::index::private_slice_index::Range]
+let core_slice_index_private_slice_index_SealedRangeUsizeInst
+  : core_slice_index_private_slice_index_Sealed (core_ops_range_Range usize) = ()
+
+// Trait implementation: [core::slice::index::Range]
+let core_slice_index_SliceIndexRangeUsizeSliceTInst (t : Type0) :
+  core_slice_index_SliceIndex (core_ops_range_Range usize) (slice t) = {
+  sealedInst = core_slice_index_private_slice_index_SealedRangeUsizeInst;
+  output = slice t;
+  get = core_slice_index_RangeUsize_get t;
+  get_mut = core_slice_index_RangeUsize_get_mut t;
+  get_mut_back = core_slice_index_RangeUsize_get_mut_back t;
+  get_unchecked = core_slice_index_RangeUsize_get_unchecked t;
+  get_unchecked_mut = core_slice_index_RangeUsize_get_unchecked_mut t;
+  index = core_slice_index_RangeUsize_index t;
+  index_mut = core_slice_index_RangeUsize_index_mut t;
+  index_mut_back = core_slice_index_RangeUsize_index_mut_back t;
+}
+
+// Trait implementation: [core::slice::index::[T]]
+let core_ops_index_IndexSliceTIInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_Index (slice t) idx = {
+  output = inst.output;
+  index = core_slice_index_Slice_index t idx inst;
+}
+
+// Trait implementation: [core::slice::index::[T]]
+let core_ops_index_IndexMutSliceTIInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_IndexMut (slice t) idx = {
+  indexInst = core_ops_index_IndexSliceTIInst t idx inst;
+  index_mut = core_slice_index_Slice_index_mut t idx inst;
+  index_mut_back = core_slice_index_Slice_index_mut_back t idx inst;
+}
+
+// Trait implementation: [core::array::[T; N]]
+let core_ops_index_IndexArrayInst (t idx : Type0) (n : usize)
+  (inst : core_ops_index_Index (slice t) idx) :
+  core_ops_index_Index (array t n) idx = {
+  output = inst.output;
+  index = core_array_Array_index t idx n inst;
+}
+
+// Trait implementation: [core::array::[T; N]]
+let core_ops_index_IndexMutArrayIInst (t idx : Type0) (n : usize)
+  (inst : core_ops_index_IndexMut (slice t) idx) :
+  core_ops_index_IndexMut (array t n) idx = {
+  indexInst = core_ops_index_IndexArrayInst t idx n inst.indexInst;
+  index_mut = core_array_Array_index_mut t idx n inst;
+  index_mut_back = core_array_Array_index_mut_back t idx n inst;
+}
+
+// [core::slice::index::usize::get]: forward function
+let core_slice_index_usize_get
+  (t : Type0) : usize → slice t → result (option t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_mut]: forward function
+let core_slice_index_usize_get_mut
+  (t : Type0) : usize → slice t → result (option t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_mut]: backward function 0
+let core_slice_index_usize_get_mut_back
+  (t : Type0) : usize → slice t → option t → result (slice t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_unchecked]: forward function
+let core_slice_index_usize_get_unchecked
+  (t : Type0) : usize → const_raw_ptr (slice t) → result (const_raw_ptr t) =
+  admit () // TODO
+
+// [core::slice::index::usize::get_unchecked_mut]: forward function
+let core_slice_index_usize_get_unchecked_mut
+  (t : Type0) : usize → mut_raw_ptr (slice t) → result (mut_raw_ptr t) =
+  admit () // TODO
+
+// [core::slice::index::usize::index]: forward function
+let core_slice_index_usize_index (t : Type0) : usize → slice t → result t =
+  admit () // TODO
+
+// [core::slice::index::usize::index_mut]: forward function
+let core_slice_index_usize_index_mut (t : Type0) : usize → slice t → result t =
+  admit () // TODO
+
+// [core::slice::index::usize::index_mut]: backward function 0
+let core_slice_index_usize_index_mut_back
+  (t : Type0) : usize → slice t → t → result (slice t) =
+  admit () // TODO
+
+// Trait implementation: [core::slice::index::private_slice_index::usize]
+let core_slice_index_private_slice_index_SealedUsizeInst
+  : core_slice_index_private_slice_index_Sealed usize = ()
+
+// Trait implementation: [core::slice::index::usize]
+let core_slice_index_SliceIndexUsizeSliceTInst (t : Type0) :
+  core_slice_index_SliceIndex usize (slice t) = {
+  sealedInst = core_slice_index_private_slice_index_SealedUsizeInst;
+  output = t;
+  get = core_slice_index_usize_get t;
+  get_mut = core_slice_index_usize_get_mut t;
+  get_mut_back = core_slice_index_usize_get_mut_back t;
+  get_unchecked = core_slice_index_usize_get_unchecked t;
+  get_unchecked_mut = core_slice_index_usize_get_unchecked_mut t;
+  index = core_slice_index_usize_index t;
+  index_mut = core_slice_index_usize_index_mut t;
+  index_mut_back = core_slice_index_usize_index_mut_back t;
+}
+
+// [alloc::vec::Vec::index]: forward function
+let alloc_vec_Vec_index (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (self : alloc_vec_Vec t) (i : idx) : result inst.output =
+  admit () // TODO
+
+// [alloc::vec::Vec::index_mut]: forward function
+let alloc_vec_Vec_index_mut (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (self : alloc_vec_Vec t) (i : idx) : result inst.output =
+  admit () // TODO
+
+// [alloc::vec::Vec::index_mut]: backward function 0
+let alloc_vec_Vec_index_mut_back
+  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
+  (self : alloc_vec_Vec t) (i : idx) (x : inst.output) : result (alloc_vec_Vec t) =
+  admit () // TODO
+
+// Trait implementation: [alloc::vec::Vec]
+let alloc_vec_Vec_coreopsindexIndexInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_Index (alloc_vec_Vec t) idx = {
+  output = inst.output;
+  index = alloc_vec_Vec_index t idx inst;
+}
+
+// Trait implementation: [alloc::vec::Vec]
+let alloc_vec_Vec_coreopsindexIndexMutInst (t idx : Type0)
+  (inst : core_slice_index_SliceIndex idx (slice t)) :
+  core_ops_index_IndexMut (alloc_vec_Vec t) idx = {
+  indexInst = alloc_vec_Vec_coreopsindexIndexInst t idx inst;
+  index_mut = alloc_vec_Vec_index_mut t idx inst;
+  index_mut_back = alloc_vec_Vec_index_mut_back t idx inst;
+}
+
+(*** Theorems *)
+
+let alloc_vec_Vec_index_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
+  Lemma (
+    alloc_vec_Vec_index a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i ==
+      alloc_vec_Vec_index_usize v i)
+  [SMTPat (alloc_vec_Vec_index a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i)]
+  =
+  admit()
+
+let alloc_vec_Vec_index_mut_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
+  Lemma (
+    alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i ==
+      alloc_vec_Vec_index_usize v i)
+  [SMTPat (alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i)]
+  =
+  admit()
+
+let alloc_vec_Vec_index_mut_back_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) :
+  Lemma (
+    alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x ==
+      alloc_vec_Vec_update_usize v i x)
+  [SMTPat (alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x)]
+  =
+  admit()
diff --git a/tests/fstar-split/traits/Traits.fst b/tests/fstar-split/traits/Traits.fst
new file mode 100644
index 00000000..29a001b2
--- /dev/null
+++ b/tests/fstar-split/traits/Traits.fst
@@ -0,0 +1,476 @@
+(** THIS FILE WAS AUTOMATICALLY GENERATED BY AENEAS *)
+(** [traits] *)
+module Traits
+open Primitives
+
+#set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
+
+(** Trait declaration: [traits::BoolTrait]
+    Source: 'src/traits.rs', lines 1:0-1:19 *)
+noeq type boolTrait_t (self : Type0) = { get_bool : self -> result bool; }
+
+(** [traits::{bool}::get_bool]: forward function
+    Source: 'src/traits.rs', lines 12:4-12:30 *)
+let bool_get_bool (self : bool) : result bool =
+  Return self
+
+(** Trait implementation: [traits::{bool}]
+    Source: 'src/traits.rs', lines 11:0-11:23 *)
+let traits_BoolTraitBoolInst : boolTrait_t bool = { get_bool = bool_get_bool; }
+
+(** [traits::BoolTrait::ret_true]: forward function
+    Source: 'src/traits.rs', lines 6:4-6:30 *)
+let boolTrait_ret_true
+  (#self : Type0) (self_clause : boolTrait_t self) (self1 : self) :
+  result bool
+  =
+  Return true
+
+(** [traits::test_bool_trait_bool]: forward function
+    Source: 'src/traits.rs', lines 17:0-17:44 *)
+let test_bool_trait_bool (x : bool) : result bool =
+  let* b = bool_get_bool x in
+  if b then boolTrait_ret_true traits_BoolTraitBoolInst x else Return false
+
+(** [traits::{core::option::Option<T>#1}::get_bool]: forward function
+    Source: 'src/traits.rs', lines 23:4-23:30 *)
+let option_get_bool (t : Type0) (self : option t) : result bool =
+  begin match self with | None -> Return false | Some _ -> Return true end
+
+(** Trait implementation: [traits::{core::option::Option<T>#1}]
+    Source: 'src/traits.rs', lines 22:0-22:31 *)
+let traits_BoolTraitcoreoptionOptionTInst (t : Type0) : boolTrait_t (option t)
+  = {
+  get_bool = option_get_bool t;
+}
+
+(** [traits::test_bool_trait_option]: forward function
+    Source: 'src/traits.rs', lines 31:0-31:54 *)
+let test_bool_trait_option (t : Type0) (x : option t) : result bool =
+  let* b = option_get_bool t x in
+  if b
+  then boolTrait_ret_true (traits_BoolTraitcoreoptionOptionTInst t) x
+  else Return false
+
+(** [traits::test_bool_trait]: forward function
+    Source: 'src/traits.rs', lines 35:0-35:50 *)
+let test_bool_trait
+  (t : Type0) (boolTraitTInst : boolTrait_t t) (x : t) : result bool =
+  boolTraitTInst.get_bool x
+
+(** Trait declaration: [traits::ToU64]
+    Source: 'src/traits.rs', lines 39:0-39:15 *)
+noeq type toU64_t (self : Type0) = { to_u64 : self -> result u64; }
+
+(** [traits::{u64#2}::to_u64]: forward function
+    Source: 'src/traits.rs', lines 44:4-44:26 *)
+let u64_to_u64 (self : u64) : result u64 =
+  Return self
+
+(** Trait implementation: [traits::{u64#2}]
+    Source: 'src/traits.rs', lines 43:0-43:18 *)
+let traits_ToU64U64Inst : toU64_t u64 = { to_u64 = u64_to_u64; }
+
+(** [traits::{(A, A)#3}::to_u64]: forward function
+    Source: 'src/traits.rs', lines 50:4-50:26 *)
+let pair_to_u64
+  (a : Type0) (toU64AInst : toU64_t a) (self : (a & a)) : result u64 =
+  let (x, x1) = self in
+  let* i = toU64AInst.to_u64 x in
+  let* i1 = toU64AInst.to_u64 x1 in
+  u64_add i i1
+
+(** Trait implementation: [traits::{(A, A)#3}]
+    Source: 'src/traits.rs', lines 49:0-49:31 *)
+let traits_ToU64TupleAAInst (a : Type0) (toU64AInst : toU64_t a) : toU64_t (a &
+  a) = {
+  to_u64 = pair_to_u64 a toU64AInst;
+}
+
+(** [traits::f]: forward function
+    Source: 'src/traits.rs', lines 55:0-55:36 *)
+let f (t : Type0) (toU64TInst : toU64_t t) (x : (t & t)) : result u64 =
+  pair_to_u64 t toU64TInst x
+
+(** [traits::g]: forward function
+    Source: 'src/traits.rs', lines 59:0-61:18 *)
+let g
+  (t : Type0) (toU64TupleTTInst : toU64_t (t & t)) (x : (t & t)) : result u64 =
+  toU64TupleTTInst.to_u64 x
+
+(** [traits::h0]: forward function
+    Source: 'src/traits.rs', lines 66:0-66:24 *)
+let h0 (x : u64) : result u64 =
+  u64_to_u64 x
+
+(** [traits::Wrapper]
+    Source: 'src/traits.rs', lines 70:0-70:21 *)
+type wrapper_t (t : Type0) = { x : t; }
+
+(** [traits::{traits::Wrapper<T>#4}::to_u64]: forward function
+    Source: 'src/traits.rs', lines 75:4-75:26 *)
+let wrapper_to_u64
+  (t : Type0) (toU64TInst : toU64_t t) (self : wrapper_t t) : result u64 =
+  toU64TInst.to_u64 self.x
+
+(** Trait implementation: [traits::{traits::Wrapper<T>#4}]
+    Source: 'src/traits.rs', lines 74:0-74:35 *)
+let traits_ToU64traitsWrapperTInst (t : Type0) (toU64TInst : toU64_t t) :
+  toU64_t (wrapper_t t) = {
+  to_u64 = wrapper_to_u64 t toU64TInst;
+}
+
+(** [traits::h1]: forward function
+    Source: 'src/traits.rs', lines 80:0-80:33 *)
+let h1 (x : wrapper_t u64) : result u64 =
+  wrapper_to_u64 u64 traits_ToU64U64Inst x
+
+(** [traits::h2]: forward function
+    Source: 'src/traits.rs', lines 84:0-84:41 *)
+let h2 (t : Type0) (toU64TInst : toU64_t t) (x : wrapper_t t) : result u64 =
+  wrapper_to_u64 t toU64TInst x
+
+(** Trait declaration: [traits::ToType]
+    Source: 'src/traits.rs', lines 88:0-88:19 *)
+noeq type toType_t (self t : Type0) = { to_type : self -> result t; }
+
+(** [traits::{u64#5}::to_type]: forward function
+    Source: 'src/traits.rs', lines 93:4-93:28 *)
+let u64_to_type (self : u64) : result bool =
+  Return (self > 0)
+
+(** Trait implementation: [traits::{u64#5}]
+    Source: 'src/traits.rs', lines 92:0-92:25 *)
+let traits_ToTypeU64BoolInst : toType_t u64 bool = { to_type = u64_to_type; }
+
+(** Trait declaration: [traits::OfType]
+    Source: 'src/traits.rs', lines 98:0-98:16 *)
+noeq type ofType_t (self : Type0) = {
+  of_type : (t : Type0) -> (toTypeTSelfInst : toType_t t self) -> t -> result
+    self;
+}
+
+(** [traits::h3]: forward function
+    Source: 'src/traits.rs', lines 104:0-104:50 *)
+let h3
+  (t1 t2 : Type0) (ofTypeT1Inst : ofType_t t1) (toTypeT2T1Inst : toType_t t2
+  t1) (y : t2) :
+  result t1
+  =
+  ofTypeT1Inst.of_type t2 toTypeT2T1Inst y
+
+(** Trait declaration: [traits::OfTypeBis]
+    Source: 'src/traits.rs', lines 109:0-109:36 *)
+noeq type ofTypeBis_t (self t : Type0) = {
+  toTypeTSelfInst : toType_t t self;
+  of_type : t -> result self;
+}
+
+(** [traits::h4]: forward function
+    Source: 'src/traits.rs', lines 118:0-118:57 *)
+let h4
+  (t1 t2 : Type0) (ofTypeBisT1T2Inst : ofTypeBis_t t1 t2) (toTypeT2T1Inst :
+  toType_t t2 t1) (y : t2) :
+  result t1
+  =
+  ofTypeBisT1T2Inst.of_type y
+
+(** [traits::TestType]
+    Source: 'src/traits.rs', lines 122:0-122:22 *)
+type testType_t (t : Type0) = t
+
+(** [traits::{traits::TestType<T>#6}::test::TestType1]
+    Source: 'src/traits.rs', lines 127:8-127:24 *)
+type testType_test_TestType1_t = u64
+
+(** Trait declaration: [traits::{traits::TestType<T>#6}::test::TestTrait]
+    Source: 'src/traits.rs', lines 128:8-128:23 *)
+noeq type testType_test_TestTrait_t (self : Type0) = {
+  test : self -> result bool;
+}
+
+(** [traits::{traits::TestType<T>#6}::test::{traits::{traits::TestType<T>#6}::test::TestType1}::test]: forward function
+    Source: 'src/traits.rs', lines 139:12-139:34 *)
+let testType_test_TestType1_test
+  (self : testType_test_TestType1_t) : result bool =
+  Return (self > 1)
+
+(** Trait implementation: [traits::{traits::TestType<T>#6}::test::{traits::{traits::TestType<T>#6}::test::TestType1}]
+    Source: 'src/traits.rs', lines 138:8-138:36 *)
+let traits_TestType_test_TestTraittraitstraitsTestTypeTtestTestType1Inst :
+  testType_test_TestTrait_t testType_test_TestType1_t = {
+  test = testType_test_TestType1_test;
+}
+
+(** [traits::{traits::TestType<T>#6}::test]: forward function
+    Source: 'src/traits.rs', lines 126:4-126:36 *)
+let testType_test
+  (t : Type0) (toU64TInst : toU64_t t) (self : testType_t t) (x : t) :
+  result bool
+  =
+  let* x1 = toU64TInst.to_u64 x in
+  if x1 > 0 then testType_test_TestType1_test 0 else Return false
+
+(** [traits::BoolWrapper]
+    Source: 'src/traits.rs', lines 150:0-150:22 *)
+type boolWrapper_t = bool
+
+(** [traits::{traits::BoolWrapper#7}::to_type]: forward function
+    Source: 'src/traits.rs', lines 156:4-156:25 *)
+let boolWrapper_to_type
+  (t : Type0) (toTypeBoolTInst : toType_t bool t) (self : boolWrapper_t) :
+  result t
+  =
+  toTypeBoolTInst.to_type self
+
+(** Trait implementation: [traits::{traits::BoolWrapper#7}]
+    Source: 'src/traits.rs', lines 152:0-152:33 *)
+let traits_ToTypetraitsBoolWrapperTInst (t : Type0) (toTypeBoolTInst : toType_t
+  bool t) : toType_t boolWrapper_t t = {
+  to_type = boolWrapper_to_type t toTypeBoolTInst;
+}
+
+(** [traits::WithConstTy::LEN2]
+    Source: 'src/traits.rs', lines 164:4-164:21 *)
+let with_const_ty_len2_body : result usize = Return 32
+let with_const_ty_len2_c : usize = eval_global with_const_ty_len2_body
+
+(** Trait declaration: [traits::WithConstTy]
+    Source: 'src/traits.rs', lines 161:0-161:39 *)
+noeq type withConstTy_t (self : Type0) (len : usize) = {
+  cLEN1 : usize;
+  cLEN2 : usize;
+  tV : Type0;
+  tW : Type0;
+  tW_clause_0 : toU64_t tW;
+  f : tW -> array u8 len -> result tW;
+}
+
+(** [traits::{bool#8}::LEN1]
+    Source: 'src/traits.rs', lines 175:4-175:21 *)
+let bool_len1_body : result usize = Return 12
+let bool_len1_c : usize = eval_global bool_len1_body
+
+(** [traits::{bool#8}::f]: merged forward/backward function
+    (there is a single backward function, and the forward function returns ())
+    Source: 'src/traits.rs', lines 180:4-180:39 *)
+let bool_f (i : u64) (a : array u8 32) : result u64 =
+  Return i
+
+(** Trait implementation: [traits::{bool#8}]
+    Source: 'src/traits.rs', lines 174:0-174:29 *)
+let traits_WithConstTyBool32Inst : withConstTy_t bool 32 = {
+  cLEN1 = bool_len1_c;
+  cLEN2 = with_const_ty_len2_c;
+  tV = u8;
+  tW = u64;
+  tW_clause_0 = traits_ToU64U64Inst;
+  f = bool_f;
+}
+
+(** [traits::use_with_const_ty1]: forward function
+    Source: 'src/traits.rs', lines 183:0-183:75 *)
+let use_with_const_ty1
+  (h : Type0) (len : usize) (withConstTyHLENInst : withConstTy_t h len) :
+  result usize
+  =
+  let i = withConstTyHLENInst.cLEN1 in Return i
+
+(** [traits::use_with_const_ty2]: forward function
+    Source: 'src/traits.rs', lines 187:0-187:73 *)
+let use_with_const_ty2
+  (h : Type0) (len : usize) (withConstTyHLENInst : withConstTy_t h len)
+  (w : withConstTyHLENInst.tW) :
+  result unit
+  =
+  Return ()
+
+(** [traits::use_with_const_ty3]: forward function
+    Source: 'src/traits.rs', lines 189:0-189:80 *)
+let use_with_const_ty3
+  (h : Type0) (len : usize) (withConstTyHLENInst : withConstTy_t h len)
+  (x : withConstTyHLENInst.tW) :
+  result u64
+  =
+  withConstTyHLENInst.tW_clause_0.to_u64 x
+
+(** [traits::test_where1]: forward function
+    Source: 'src/traits.rs', lines 193:0-193:40 *)
+let test_where1 (t : Type0) (_x : t) : result unit =
+  Return ()
+
+(** [traits::test_where2]: forward function
+    Source: 'src/traits.rs', lines 194:0-194:57 *)
+let test_where2
+  (t : Type0) (withConstTyT32Inst : withConstTy_t t 32) (_x : u32) :
+  result unit
+  =
+  Return ()
+
+(** Trait declaration: [traits::ParentTrait0]
+    Source: 'src/traits.rs', lines 200:0-200:22 *)
+noeq type parentTrait0_t (self : Type0) = {
+  tW : Type0;
+  get_name : self -> result string;
+  get_w : self -> result tW;
+}
+
+(** Trait declaration: [traits::ParentTrait1]
+    Source: 'src/traits.rs', lines 205:0-205:22 *)
+type parentTrait1_t (self : Type0) = unit
+
+(** Trait declaration: [traits::ChildTrait]
+    Source: 'src/traits.rs', lines 206:0-206:49 *)
+noeq type childTrait_t (self : Type0) = {
+  parentTrait0SelfInst : parentTrait0_t self;
+  parentTrait1SelfInst : parentTrait1_t self;
+}
+
+(** [traits::test_parent_trait0]: forward function
+    Source: 'src/traits.rs', lines 208:0-208:57 *)
+let test_parent_trait0
+  (t : Type0) (parentTrait0TInst : parentTrait0_t t) (x : t) :
+  result parentTrait0TInst.tW
+  =
+  parentTrait0TInst.get_w x
+
+(** [traits::test_child_trait1]: forward function
+    Source: 'src/traits.rs', lines 213:0-213:56 *)
+let test_child_trait1
+  (t : Type0) (childTraitTInst : childTrait_t t) (x : t) : result string =
+  childTraitTInst.parentTrait0SelfInst.get_name x
+
+(** [traits::test_child_trait2]: forward function
+    Source: 'src/traits.rs', lines 217:0-217:54 *)
+let test_child_trait2
+  (t : Type0) (childTraitTInst : childTrait_t t) (x : t) :
+  result childTraitTInst.parentTrait0SelfInst.tW
+  =
+  childTraitTInst.parentTrait0SelfInst.get_w x
+
+(** [traits::order1]: forward function
+    Source: 'src/traits.rs', lines 223:0-223:59 *)
+let order1
+  (t u : Type0) (parentTrait0TInst : parentTrait0_t t) (parentTrait0UInst :
+  parentTrait0_t u) :
+  result unit
+  =
+  Return ()
+
+(** Trait declaration: [traits::ChildTrait1]
+    Source: 'src/traits.rs', lines 226:0-226:35 *)
+noeq type childTrait1_t (self : Type0) = {
+  parentTrait1SelfInst : parentTrait1_t self;
+}
+
+(** Trait implementation: [traits::{usize#9}]
+    Source: 'src/traits.rs', lines 228:0-228:27 *)
+let traits_ParentTrait1UsizeInst : parentTrait1_t usize = ()
+
+(** Trait implementation: [traits::{usize#10}]
+    Source: 'src/traits.rs', lines 229:0-229:26 *)
+let traits_ChildTrait1UsizeInst : childTrait1_t usize = {
+  parentTrait1SelfInst = traits_ParentTrait1UsizeInst;
+}
+
+(** Trait declaration: [traits::Iterator]
+    Source: 'src/traits.rs', lines 233:0-233:18 *)
+noeq type iterator_t (self : Type0) = { tItem : Type0; }
+
+(** Trait declaration: [traits::IntoIterator]
+    Source: 'src/traits.rs', lines 237:0-237:22 *)
+noeq type intoIterator_t (self : Type0) = {
+  tItem : Type0;
+  tIntoIter : Type0;
+  tIntoIter_clause_0 : iterator_t tIntoIter;
+  into_iter : self -> result tIntoIter;
+}
+
+(** Trait declaration: [traits::FromResidual]
+    Source: 'src/traits.rs', lines 254:0-254:21 *)
+type fromResidual_t (self t : Type0) = unit
+
+(** Trait declaration: [traits::Try]
+    Source: 'src/traits.rs', lines 250:0-250:48 *)
+noeq type try_t (self : Type0) = {
+  tResidual : Type0;
+  fromResidualSelftraitsTrySelfResidualInst : fromResidual_t self tResidual;
+}
+
+(** Trait declaration: [traits::WithTarget]
+    Source: 'src/traits.rs', lines 256:0-256:20 *)
+noeq type withTarget_t (self : Type0) = { tTarget : Type0; }
+
+(** Trait declaration: [traits::ParentTrait2]
+    Source: 'src/traits.rs', lines 260:0-260:22 *)
+noeq type parentTrait2_t (self : Type0) = {
+  tU : Type0;
+  tU_clause_0 : withTarget_t tU;
+}
+
+(** Trait declaration: [traits::ChildTrait2]
+    Source: 'src/traits.rs', lines 264:0-264:35 *)
+noeq type childTrait2_t (self : Type0) = {
+  parentTrait2SelfInst : parentTrait2_t self;
+  convert : parentTrait2SelfInst.tU -> result
+    parentTrait2SelfInst.tU_clause_0.tTarget;
+}
+
+(** Trait implementation: [traits::{u32#11}]
+    Source: 'src/traits.rs', lines 268:0-268:23 *)
+let traits_WithTargetU32Inst : withTarget_t u32 = { tTarget = u32; }
+
+(** Trait implementation: [traits::{u32#12}]
+    Source: 'src/traits.rs', lines 272:0-272:25 *)
+let traits_ParentTrait2U32Inst : parentTrait2_t u32 = {
+  tU = u32;
+  tU_clause_0 = traits_WithTargetU32Inst;
+}
+
+(** [traits::{u32#13}::convert]: forward function
+    Source: 'src/traits.rs', lines 277:4-277:29 *)
+let u32_convert (x : u32) : result u32 =
+  Return x
+
+(** Trait implementation: [traits::{u32#13}]
+    Source: 'src/traits.rs', lines 276:0-276:24 *)
+let traits_ChildTrait2U32Inst : childTrait2_t u32 = {
+  parentTrait2SelfInst = traits_ParentTrait2U32Inst;
+  convert = u32_convert;
+}
+
+(** Trait declaration: [traits::CFnOnce]
+    Source: 'src/traits.rs', lines 290:0-290:23 *)
+noeq type cFnOnce_t (self args : Type0) = {
+  tOutput : Type0;
+  call_once : self -> args -> result tOutput;
+}
+
+(** Trait declaration: [traits::CFnMut]
+    Source: 'src/traits.rs', lines 296:0-296:37 *)
+noeq type cFnMut_t (self args : Type0) = {
+  cFnOnceSelfArgsInst : cFnOnce_t self args;
+  call_mut : self -> args -> result cFnOnceSelfArgsInst.tOutput;
+  call_mut_back : self -> args -> result self;
+}
+
+(** Trait declaration: [traits::CFn]
+    Source: 'src/traits.rs', lines 300:0-300:33 *)
+noeq type cFn_t (self args : Type0) = {
+  cFnMutSelfArgsInst : cFnMut_t self args;
+  call : self -> args -> result cFnMutSelfArgsInst.cFnOnceSelfArgsInst.tOutput;
+}
+
+(** Trait declaration: [traits::GetTrait]
+    Source: 'src/traits.rs', lines 304:0-304:18 *)
+noeq type getTrait_t (self : Type0) = { tW : Type0; get_w : self -> result tW;
+}
+
+(** [traits::test_get_trait]: forward function
+    Source: 'src/traits.rs', lines 309:0-309:49 *)
+let test_get_trait
+  (t : Type0) (getTraitTInst : getTrait_t t) (x : t) :
+  result getTraitTInst.tW
+  =
+  getTraitTInst.get_w x
+
diff --git a/tests/fstar/array/Array.Clauses.Template.fst b/tests/fstar/array/Array.Clauses.Template.fst
index 84347ab9..b2f2649c 100644
--- a/tests/fstar/array/Array.Clauses.Template.fst
+++ b/tests/fstar/array/Array.Clauses.Template.fst
@@ -9,13 +9,13 @@ open Array.Types
 (** [array::sum]: decreases clause
     Source: 'src/array.rs', lines 242:0-250:1 *)
 unfold
-let sum_loop_decreases (s : slice u32) (sum0 : u32) (i : usize) : nat =
+let sum_loop_decreases (s : slice u32) (sum1 : u32) (i : usize) : nat =
   admit ()
 
 (** [array::sum2]: decreases clause
     Source: 'src/array.rs', lines 252:0-261:1 *)
 unfold
-let sum2_loop_decreases (s : slice u32) (s2 : slice u32) (sum0 : u32)
+let sum2_loop_decreases (s : slice u32) (s2 : slice u32) (sum1 : u32)
   (i : usize) : nat =
   admit ()
 
diff --git a/tests/fstar/array/Array.Funs.fst b/tests/fstar/array/Array.Funs.fst
index 935bd9c9..da4164bc 100644
--- a/tests/fstar/array/Array.Funs.fst
+++ b/tests/fstar/array/Array.Funs.fst
@@ -7,86 +7,82 @@ include Array.Clauses
 
 #set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
 
-(** [array::incr]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [array::incr]:
     Source: 'src/array.rs', lines 8:0-8:24 *)
 let incr (x : u32) : result u32 =
   u32_add x 1
 
-(** [array::array_to_shared_slice_]: forward function
+(** [array::array_to_shared_slice_]:
     Source: 'src/array.rs', lines 16:0-16:53 *)
 let array_to_shared_slice_ (t : Type0) (s : array t 32) : result (slice t) =
   array_to_slice t 32 s
 
-(** [array::array_to_mut_slice_]: forward function
+(** [array::array_to_mut_slice_]:
     Source: 'src/array.rs', lines 21:0-21:58 *)
-let array_to_mut_slice_ (t : Type0) (s : array t 32) : result (slice t) =
-  array_to_slice t 32 s
-
-(** [array::array_to_mut_slice_]: backward function 0
-    Source: 'src/array.rs', lines 21:0-21:58 *)
-let array_to_mut_slice__back
-  (t : Type0) (s : array t 32) (ret : slice t) : result (array t 32) =
-  array_from_slice t 32 s ret
+let array_to_mut_slice_
+  (t : Type0) (s : array t 32) :
+  result ((slice t) & (slice t -> result (array t 32)))
+  =
+  let* (s1, to_slice_mut_back) = array_to_slice_mut t 32 s in
+  let back = fun ret -> to_slice_mut_back ret in
+  Return (s1, back)
 
-(** [array::array_len]: forward function
+(** [array::array_len]:
     Source: 'src/array.rs', lines 25:0-25:40 *)
 let array_len (t : Type0) (s : array t 32) : result usize =
-  let* s0 = array_to_slice t 32 s in let i = slice_len t s0 in Return i
+  let* s1 = array_to_slice t 32 s in let i = slice_len t s1 in Return i
 
-(** [array::shared_array_len]: forward function
+(** [array::shared_array_len]:
     Source: 'src/array.rs', lines 29:0-29:48 *)
 let shared_array_len (t : Type0) (s : array t 32) : result usize =
-  let* s0 = array_to_slice t 32 s in let i = slice_len t s0 in Return i
+  let* s1 = array_to_slice t 32 s in let i = slice_len t s1 in Return i
 
-(** [array::shared_slice_len]: forward function
+(** [array::shared_slice_len]:
     Source: 'src/array.rs', lines 33:0-33:44 *)
 let shared_slice_len (t : Type0) (s : slice t) : result usize =
   let i = slice_len t s in Return i
 
-(** [array::index_array_shared]: forward function
+(** [array::index_array_shared]:
     Source: 'src/array.rs', lines 37:0-37:57 *)
 let index_array_shared (t : Type0) (s : array t 32) (i : usize) : result t =
   array_index_usize t 32 s i
 
-(** [array::index_array_u32]: forward function
+(** [array::index_array_u32]:
     Source: 'src/array.rs', lines 44:0-44:53 *)
 let index_array_u32 (s : array u32 32) (i : usize) : result u32 =
   array_index_usize u32 32 s i
 
-(** [array::index_array_copy]: forward function
+(** [array::index_array_copy]:
     Source: 'src/array.rs', lines 48:0-48:45 *)
 let index_array_copy (x : array u32 32) : result u32 =
   array_index_usize u32 32 x 0
 
-(** [array::index_mut_array]: forward function
-    Source: 'src/array.rs', lines 52:0-52:62 *)
-let index_mut_array (t : Type0) (s : array t 32) (i : usize) : result t =
-  array_index_usize t 32 s i
-
-(** [array::index_mut_array]: backward function 0
+(** [array::index_mut_array]:
     Source: 'src/array.rs', lines 52:0-52:62 *)
-let index_mut_array_back
-  (t : Type0) (s : array t 32) (i : usize) (ret : t) : result (array t 32) =
-  array_update_usize t 32 s i ret
+let index_mut_array
+  (t : Type0) (s : array t 32) (i : usize) :
+  result (t & (t -> result (array t 32)))
+  =
+  let* (x, index_mut_back) = array_index_mut_usize t 32 s i in
+  let back = fun ret -> index_mut_back ret in
+  Return (x, back)
 
-(** [array::index_slice]: forward function
+(** [array::index_slice]:
     Source: 'src/array.rs', lines 56:0-56:46 *)
 let index_slice (t : Type0) (s : slice t) (i : usize) : result t =
   slice_index_usize t s i
 
-(** [array::index_mut_slice]: forward function
-    Source: 'src/array.rs', lines 60:0-60:58 *)
-let index_mut_slice (t : Type0) (s : slice t) (i : usize) : result t =
-  slice_index_usize t s i
-
-(** [array::index_mut_slice]: backward function 0
+(** [array::index_mut_slice]:
     Source: 'src/array.rs', lines 60:0-60:58 *)
-let index_mut_slice_back
-  (t : Type0) (s : slice t) (i : usize) (ret : t) : result (slice t) =
-  slice_update_usize t s i ret
+let index_mut_slice
+  (t : Type0) (s : slice t) (i : usize) :
+  result (t & (t -> result (slice t)))
+  =
+  let* (x, index_mut_back) = slice_index_mut_usize t s i in
+  let back = fun ret -> index_mut_back ret in
+  Return (x, back)
 
-(** [array::slice_subslice_shared_]: forward function
+(** [array::slice_subslice_shared_]:
     Source: 'src/array.rs', lines 64:0-64:70 *)
 let slice_subslice_shared_
   (x : slice u32) (y : usize) (z : usize) : result (slice u32) =
@@ -94,41 +90,35 @@ let slice_subslice_shared_
     (core_slice_index_SliceIndexRangeUsizeSliceTInst u32) x
     { start = y; end_ = z }
 
-(** [array::slice_subslice_mut_]: forward function
+(** [array::slice_subslice_mut_]:
     Source: 'src/array.rs', lines 68:0-68:75 *)
 let slice_subslice_mut_
-  (x : slice u32) (y : usize) (z : usize) : result (slice u32) =
-  core_slice_index_Slice_index_mut u32 (core_ops_range_Range usize)
-    (core_slice_index_SliceIndexRangeUsizeSliceTInst u32) x
-    { start = y; end_ = z }
-
-(** [array::slice_subslice_mut_]: backward function 0
-    Source: 'src/array.rs', lines 68:0-68:75 *)
-let slice_subslice_mut__back
-  (x : slice u32) (y : usize) (z : usize) (ret : slice u32) :
-  result (slice u32)
+  (x : slice u32) (y : usize) (z : usize) :
+  result ((slice u32) & (slice u32 -> result (slice u32)))
   =
-  core_slice_index_Slice_index_mut_back u32 (core_ops_range_Range usize)
-    (core_slice_index_SliceIndexRangeUsizeSliceTInst u32) x
-    { start = y; end_ = z } ret
-
-(** [array::array_to_slice_shared_]: forward function
+  let* (s, index_mut_back) =
+    core_slice_index_Slice_index_mut u32 (core_ops_range_Range usize)
+      (core_slice_index_SliceIndexRangeUsizeSliceTInst u32) x
+      { start = y; end_ = z } in
+  let back = fun ret -> index_mut_back ret in
+  Return (s, back)
+
+(** [array::array_to_slice_shared_]:
     Source: 'src/array.rs', lines 72:0-72:54 *)
 let array_to_slice_shared_ (x : array u32 32) : result (slice u32) =
   array_to_slice u32 32 x
 
-(** [array::array_to_slice_mut_]: forward function
+(** [array::array_to_slice_mut_]:
     Source: 'src/array.rs', lines 76:0-76:59 *)
-let array_to_slice_mut_ (x : array u32 32) : result (slice u32) =
-  array_to_slice u32 32 x
-
-(** [array::array_to_slice_mut_]: backward function 0
-    Source: 'src/array.rs', lines 76:0-76:59 *)
-let array_to_slice_mut__back
-  (x : array u32 32) (ret : slice u32) : result (array u32 32) =
-  array_from_slice u32 32 x ret
+let array_to_slice_mut_
+  (x : array u32 32) :
+  result ((slice u32) & (slice u32 -> result (array u32 32)))
+  =
+  let* (s, to_slice_mut_back) = array_to_slice_mut u32 32 x in
+  let back = fun ret -> to_slice_mut_back ret in
+  Return (s, back)
 
-(** [array::array_subslice_shared_]: forward function
+(** [array::array_subslice_shared_]:
     Source: 'src/array.rs', lines 80:0-80:74 *)
 let array_subslice_shared_
   (x : array u32 32) (y : usize) (z : usize) : result (slice u32) =
@@ -137,274 +127,263 @@ let array_subslice_shared_
     (core_slice_index_SliceIndexRangeUsizeSliceTInst u32)) x
     { start = y; end_ = z }
 
-(** [array::array_subslice_mut_]: forward function
+(** [array::array_subslice_mut_]:
     Source: 'src/array.rs', lines 84:0-84:79 *)
 let array_subslice_mut_
-  (x : array u32 32) (y : usize) (z : usize) : result (slice u32) =
-  core_array_Array_index_mut u32 (core_ops_range_Range usize) 32
-    (core_ops_index_IndexMutSliceTIInst u32 (core_ops_range_Range usize)
-    (core_slice_index_SliceIndexRangeUsizeSliceTInst u32)) x
-    { start = y; end_ = z }
-
-(** [array::array_subslice_mut_]: backward function 0
-    Source: 'src/array.rs', lines 84:0-84:79 *)
-let array_subslice_mut__back
-  (x : array u32 32) (y : usize) (z : usize) (ret : slice u32) :
-  result (array u32 32)
+  (x : array u32 32) (y : usize) (z : usize) :
+  result ((slice u32) & (slice u32 -> result (array u32 32)))
   =
-  core_array_Array_index_mut_back u32 (core_ops_range_Range usize) 32
-    (core_ops_index_IndexMutSliceTIInst u32 (core_ops_range_Range usize)
-    (core_slice_index_SliceIndexRangeUsizeSliceTInst u32)) x
-    { start = y; end_ = z } ret
+  let* (s, index_mut_back) =
+    core_array_Array_index_mut u32 (core_ops_range_Range usize) 32
+      (core_ops_index_IndexMutSliceTIInst u32 (core_ops_range_Range usize)
+      (core_slice_index_SliceIndexRangeUsizeSliceTInst u32)) x
+      { start = y; end_ = z } in
+  let back = fun ret -> index_mut_back ret in
+  Return (s, back)
 
-(** [array::index_slice_0]: forward function
+(** [array::index_slice_0]:
     Source: 'src/array.rs', lines 88:0-88:38 *)
 let index_slice_0 (t : Type0) (s : slice t) : result t =
   slice_index_usize t s 0
 
-(** [array::index_array_0]: forward function
+(** [array::index_array_0]:
     Source: 'src/array.rs', lines 92:0-92:42 *)
 let index_array_0 (t : Type0) (s : array t 32) : result t =
   array_index_usize t 32 s 0
 
-(** [array::index_index_array]: forward function
+(** [array::index_index_array]:
     Source: 'src/array.rs', lines 103:0-103:71 *)
 let index_index_array
   (s : array (array u32 32) 32) (i : usize) (j : usize) : result u32 =
   let* a = array_index_usize (array u32 32) 32 s i in
   array_index_usize u32 32 a j
 
-(** [array::update_update_array]: forward function
+(** [array::update_update_array]:
     Source: 'src/array.rs', lines 114:0-114:70 *)
 let update_update_array
   (s : array (array u32 32) 32) (i : usize) (j : usize) : result unit =
-  let* a = array_index_usize (array u32 32) 32 s i in
-  let* a0 = array_update_usize u32 32 a j 0 in
-  let* _ = array_update_usize (array u32 32) 32 s i a0 in
+  let* (a, index_mut_back) = array_index_mut_usize (array u32 32) 32 s i in
+  let* (_, index_mut_back1) = array_index_mut_usize u32 32 a j in
+  let* a1 = index_mut_back1 0 in
+  let* _ = index_mut_back a1 in
   Return ()
 
-(** [array::array_local_deep_copy]: forward function
+(** [array::array_local_deep_copy]:
     Source: 'src/array.rs', lines 118:0-118:43 *)
 let array_local_deep_copy (x : array u32 32) : result unit =
   Return ()
 
-(** [array::take_array]: forward function
+(** [array::take_array]:
     Source: 'src/array.rs', lines 122:0-122:30 *)
 let take_array (a : array u32 2) : result unit =
   Return ()
 
-(** [array::take_array_borrow]: forward function
+(** [array::take_array_borrow]:
     Source: 'src/array.rs', lines 123:0-123:38 *)
 let take_array_borrow (a : array u32 2) : result unit =
   Return ()
 
-(** [array::take_slice]: forward function
+(** [array::take_slice]:
     Source: 'src/array.rs', lines 124:0-124:28 *)
 let take_slice (s : slice u32) : result unit =
   Return ()
 
-(** [array::take_mut_slice]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [array::take_mut_slice]:
     Source: 'src/array.rs', lines 125:0-125:36 *)
 let take_mut_slice (s : slice u32) : result (slice u32) =
   Return s
 
-(** [array::const_array]: forward function
+(** [array::const_array]:
     Source: 'src/array.rs', lines 127:0-127:32 *)
 let const_array : result (array u32 2) =
   Return (mk_array u32 2 [ 0; 0 ])
 
-(** [array::const_slice]: forward function
+(** [array::const_slice]:
     Source: 'src/array.rs', lines 131:0-131:20 *)
 let const_slice : result unit =
   let* _ = array_to_slice u32 2 (mk_array u32 2 [ 0; 0 ]) in Return ()
 
-(** [array::take_all]: forward function
+(** [array::take_all]:
     Source: 'src/array.rs', lines 141:0-141:17 *)
 let take_all : result unit =
   let* _ = take_array (mk_array u32 2 [ 0; 0 ]) in
+  let* _ = take_array (mk_array u32 2 [ 0; 0 ]) in
   let* _ = take_array_borrow (mk_array u32 2 [ 0; 0 ]) in
   let* s = array_to_slice u32 2 (mk_array u32 2 [ 0; 0 ]) in
   let* _ = take_slice s in
-  let* s0 = array_to_slice u32 2 (mk_array u32 2 [ 0; 0 ]) in
-  let* s1 = take_mut_slice s0 in
-  let* _ = array_from_slice u32 2 (mk_array u32 2 [ 0; 0 ]) s1 in
+  let* (s1, to_slice_mut_back) =
+    array_to_slice_mut u32 2 (mk_array u32 2 [ 0; 0 ]) in
+  let* s2 = take_mut_slice s1 in
+  let* _ = to_slice_mut_back s2 in
   Return ()
 
-(** [array::index_array]: forward function
+(** [array::index_array]:
     Source: 'src/array.rs', lines 155:0-155:38 *)
 let index_array (x : array u32 2) : result u32 =
   array_index_usize u32 2 x 0
 
-(** [array::index_array_borrow]: forward function
+(** [array::index_array_borrow]:
     Source: 'src/array.rs', lines 158:0-158:46 *)
 let index_array_borrow (x : array u32 2) : result u32 =
   array_index_usize u32 2 x 0
 
-(** [array::index_slice_u32_0]: forward function
+(** [array::index_slice_u32_0]:
     Source: 'src/array.rs', lines 162:0-162:42 *)
 let index_slice_u32_0 (x : slice u32) : result u32 =
   slice_index_usize u32 x 0
 
-(** [array::index_mut_slice_u32_0]: forward function
-    Source: 'src/array.rs', lines 166:0-166:50 *)
-let index_mut_slice_u32_0 (x : slice u32) : result u32 =
-  slice_index_usize u32 x 0
-
-(** [array::index_mut_slice_u32_0]: backward function 0
+(** [array::index_mut_slice_u32_0]:
     Source: 'src/array.rs', lines 166:0-166:50 *)
-let index_mut_slice_u32_0_back (x : slice u32) : result (slice u32) =
-  let* _ = slice_index_usize u32 x 0 in Return x
+let index_mut_slice_u32_0 (x : slice u32) : result (u32 & (slice u32)) =
+  let* i = slice_index_usize u32 x 0 in Return (i, x)
 
-(** [array::index_all]: forward function
+(** [array::index_all]:
     Source: 'src/array.rs', lines 170:0-170:25 *)
 let index_all : result u32 =
   let* i = index_array (mk_array u32 2 [ 0; 0 ]) in
-  let* i0 = index_array (mk_array u32 2 [ 0; 0 ]) in
-  let* i1 = u32_add i i0 in
-  let* i2 = index_array_borrow (mk_array u32 2 [ 0; 0 ]) in
-  let* i3 = u32_add i1 i2 in
+  let* i1 = index_array (mk_array u32 2 [ 0; 0 ]) in
+  let* i2 = u32_add i i1 in
+  let* i3 = index_array_borrow (mk_array u32 2 [ 0; 0 ]) in
+  let* i4 = u32_add i2 i3 in
   let* s = array_to_slice u32 2 (mk_array u32 2 [ 0; 0 ]) in
-  let* i4 = index_slice_u32_0 s in
-  let* i5 = u32_add i3 i4 in
-  let* s0 = array_to_slice u32 2 (mk_array u32 2 [ 0; 0 ]) in
-  let* i6 = index_mut_slice_u32_0 s0 in
-  let* i7 = u32_add i5 i6 in
-  let* s1 = index_mut_slice_u32_0_back s0 in
-  let* _ = array_from_slice u32 2 (mk_array u32 2 [ 0; 0 ]) s1 in
-  Return i7
-
-(** [array::update_array]: forward function
+  let* i5 = index_slice_u32_0 s in
+  let* i6 = u32_add i4 i5 in
+  let* (s1, to_slice_mut_back) =
+    array_to_slice_mut u32 2 (mk_array u32 2 [ 0; 0 ]) in
+  let* (i7, s2) = index_mut_slice_u32_0 s1 in
+  let* i8 = u32_add i6 i7 in
+  let* _ = to_slice_mut_back s2 in
+  Return i8
+
+(** [array::update_array]:
     Source: 'src/array.rs', lines 184:0-184:36 *)
 let update_array (x : array u32 2) : result unit =
-  let* _ = array_update_usize u32 2 x 0 1 in Return ()
+  let* (_, index_mut_back) = array_index_mut_usize u32 2 x 0 in
+  let* _ = index_mut_back 1 in
+  Return ()
 
-(** [array::update_array_mut_borrow]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [array::update_array_mut_borrow]:
     Source: 'src/array.rs', lines 187:0-187:48 *)
 let update_array_mut_borrow (x : array u32 2) : result (array u32 2) =
-  array_update_usize u32 2 x 0 1
+  let* (_, index_mut_back) = array_index_mut_usize u32 2 x 0 in
+  index_mut_back 1
 
-(** [array::update_mut_slice]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [array::update_mut_slice]:
     Source: 'src/array.rs', lines 190:0-190:38 *)
 let update_mut_slice (x : slice u32) : result (slice u32) =
-  slice_update_usize u32 x 0 1
+  let* (_, index_mut_back) = slice_index_mut_usize u32 x 0 in index_mut_back 1
 
-(** [array::update_all]: forward function
+(** [array::update_all]:
     Source: 'src/array.rs', lines 194:0-194:19 *)
 let update_all : result unit =
   let* _ = update_array (mk_array u32 2 [ 0; 0 ]) in
-  let* x = update_array_mut_borrow (mk_array u32 2 [ 0; 0 ]) in
-  let* s = array_to_slice u32 2 x in
-  let* s0 = update_mut_slice s in
-  let* _ = array_from_slice u32 2 x s0 in
+  let* _ = update_array (mk_array u32 2 [ 0; 0 ]) in
+  let* a = update_array_mut_borrow (mk_array u32 2 [ 0; 0 ]) in
+  let* (s, to_slice_mut_back) = array_to_slice_mut u32 2 a in
+  let* s1 = update_mut_slice s in
+  let* _ = to_slice_mut_back s1 in
   Return ()
 
-(** [array::range_all]: forward function
+(** [array::range_all]:
     Source: 'src/array.rs', lines 205:0-205:18 *)
 let range_all : result unit =
-  let* s =
+  let* (s, index_mut_back) =
     core_array_Array_index_mut u32 (core_ops_range_Range usize) 4
       (core_ops_index_IndexMutSliceTIInst u32 (core_ops_range_Range usize)
       (core_slice_index_SliceIndexRangeUsizeSliceTInst u32))
       (mk_array u32 4 [ 0; 0; 0; 0 ]) { start = 1; end_ = 3 } in
-  let* s0 = update_mut_slice s in
-  let* _ =
-    core_array_Array_index_mut_back u32 (core_ops_range_Range usize) 4
-      (core_ops_index_IndexMutSliceTIInst u32 (core_ops_range_Range usize)
-      (core_slice_index_SliceIndexRangeUsizeSliceTInst u32))
-      (mk_array u32 4 [ 0; 0; 0; 0 ]) { start = 1; end_ = 3 } s0 in
+  let* s1 = update_mut_slice s in
+  let* _ = index_mut_back s1 in
   Return ()
 
-(** [array::deref_array_borrow]: forward function
+(** [array::deref_array_borrow]:
     Source: 'src/array.rs', lines 214:0-214:46 *)
 let deref_array_borrow (x : array u32 2) : result u32 =
   array_index_usize u32 2 x 0
 
-(** [array::deref_array_mut_borrow]: forward function
+(** [array::deref_array_mut_borrow]:
     Source: 'src/array.rs', lines 219:0-219:54 *)
-let deref_array_mut_borrow (x : array u32 2) : result u32 =
-  array_index_usize u32 2 x 0
+let deref_array_mut_borrow (x : array u32 2) : result (u32 & (array u32 2)) =
+  let* i = array_index_usize u32 2 x 0 in Return (i, x)
 
-(** [array::deref_array_mut_borrow]: backward function 0
-    Source: 'src/array.rs', lines 219:0-219:54 *)
-let deref_array_mut_borrow_back (x : array u32 2) : result (array u32 2) =
-  let* _ = array_index_usize u32 2 x 0 in Return x
-
-(** [array::take_array_t]: forward function
+(** [array::take_array_t]:
     Source: 'src/array.rs', lines 227:0-227:31 *)
 let take_array_t (a : array aB_t 2) : result unit =
   Return ()
 
-(** [array::non_copyable_array]: forward function
+(** [array::non_copyable_array]:
     Source: 'src/array.rs', lines 229:0-229:27 *)
 let non_copyable_array : result unit =
   let* _ = take_array_t (mk_array aB_t 2 [ AB_A; AB_B ]) in Return ()
 
-(** [array::sum]: loop 0: forward function
+(** [array::sum]: loop 0:
     Source: 'src/array.rs', lines 242:0-250:1 *)
 let rec sum_loop
-  (s : slice u32) (sum0 : u32) (i : usize) :
-  Tot (result u32) (decreases (sum_loop_decreases s sum0 i))
+  (s : slice u32) (sum1 : u32) (i : usize) :
+  Tot (result u32) (decreases (sum_loop_decreases s sum1 i))
   =
-  let i0 = slice_len u32 s in
-  if i < i0
+  let i1 = slice_len u32 s in
+  if i < i1
   then
-    let* i1 = slice_index_usize u32 s i in
-    let* sum1 = u32_add sum0 i1 in
-    let* i2 = usize_add i 1 in
-    sum_loop s sum1 i2
-  else Return sum0
+    let* i2 = slice_index_usize u32 s i in
+    let* sum3 = u32_add sum1 i2 in
+    let* i3 = usize_add i 1 in
+    sum_loop s sum3 i3
+  else Return sum1
 
-(** [array::sum]: forward function
+(** [array::sum]:
     Source: 'src/array.rs', lines 242:0-242:28 *)
 let sum (s : slice u32) : result u32 =
   sum_loop s 0 0
 
-(** [array::sum2]: loop 0: forward function
+(** [array::sum2]: loop 0:
     Source: 'src/array.rs', lines 252:0-261:1 *)
 let rec sum2_loop
-  (s : slice u32) (s2 : slice u32) (sum0 : u32) (i : usize) :
-  Tot (result u32) (decreases (sum2_loop_decreases s s2 sum0 i))
+  (s : slice u32) (s2 : slice u32) (sum1 : u32) (i : usize) :
+  Tot (result u32) (decreases (sum2_loop_decreases s s2 sum1 i))
   =
-  let i0 = slice_len u32 s in
-  if i < i0
+  let i1 = slice_len u32 s in
+  if i < i1
   then
-    let* i1 = slice_index_usize u32 s i in
-    let* i2 = slice_index_usize u32 s2 i in
-    let* i3 = u32_add i1 i2 in
-    let* sum1 = u32_add sum0 i3 in
-    let* i4 = usize_add i 1 in
-    sum2_loop s s2 sum1 i4
-  else Return sum0
-
-(** [array::sum2]: forward function
+    let* i2 = slice_index_usize u32 s i in
+    let* i3 = slice_index_usize u32 s2 i in
+    let* i4 = u32_add i2 i3 in
+    let* sum3 = u32_add sum1 i4 in
+    let* i5 = usize_add i 1 in
+    sum2_loop s s2 sum3 i5
+  else Return sum1
+
+(** [array::sum2]:
     Source: 'src/array.rs', lines 252:0-252:41 *)
 let sum2 (s : slice u32) (s2 : slice u32) : result u32 =
   let i = slice_len u32 s in
-  let i0 = slice_len u32 s2 in
-  if not (i = i0) then Fail Failure else sum2_loop s s2 0 0
+  let i1 = slice_len u32 s2 in
+  if not (i = i1) then Fail Failure else sum2_loop s s2 0 0
 
-(** [array::f0]: forward function
+(** [array::f0]:
     Source: 'src/array.rs', lines 263:0-263:11 *)
 let f0 : result unit =
-  let* s = array_to_slice u32 2 (mk_array u32 2 [ 1; 2 ]) in
-  let* s0 = slice_update_usize u32 s 0 1 in
-  let* _ = array_from_slice u32 2 (mk_array u32 2 [ 1; 2 ]) s0 in
+  let* (s, to_slice_mut_back) =
+    array_to_slice_mut u32 2 (mk_array u32 2 [ 1; 2 ]) in
+  let* (_, index_mut_back) = slice_index_mut_usize u32 s 0 in
+  let* s1 = index_mut_back 1 in
+  let* _ = to_slice_mut_back s1 in
   Return ()
 
-(** [array::f1]: forward function
+(** [array::f1]:
     Source: 'src/array.rs', lines 268:0-268:11 *)
 let f1 : result unit =
-  let* _ = array_update_usize u32 2 (mk_array u32 2 [ 1; 2 ]) 0 1 in Return ()
+  let* (_, index_mut_back) =
+    array_index_mut_usize u32 2 (mk_array u32 2 [ 1; 2 ]) 0 in
+  let* _ = index_mut_back 1 in
+  Return ()
 
-(** [array::f2]: forward function
+(** [array::f2]:
     Source: 'src/array.rs', lines 273:0-273:17 *)
 let f2 (i : u32) : result unit =
   Return ()
 
-(** [array::f4]: forward function
+(** [array::f4]:
     Source: 'src/array.rs', lines 282:0-282:54 *)
 let f4 (x : array u32 32) (y : usize) (z : usize) : result (slice u32) =
   core_array_Array_index u32 (core_ops_range_Range usize) 32
@@ -412,34 +391,36 @@ let f4 (x : array u32 32) (y : usize) (z : usize) : result (slice u32) =
     (core_slice_index_SliceIndexRangeUsizeSliceTInst u32)) x
     { start = y; end_ = z }
 
-(** [array::f3]: forward function
+(** [array::f3]:
     Source: 'src/array.rs', lines 275:0-275:18 *)
 let f3 : result u32 =
   let* i = array_index_usize u32 2 (mk_array u32 2 [ 1; 2 ]) 0 in
   let* _ = f2 i in
   let b = array_repeat u32 32 0 in
   let* s = array_to_slice u32 2 (mk_array u32 2 [ 1; 2 ]) in
-  let* s0 = f4 b 16 18 in
-  sum2 s s0
+  let* s1 = f4 b 16 18 in
+  sum2 s s1
 
 (** [array::SZ]
     Source: 'src/array.rs', lines 286:0-286:19 *)
 let sz_body : result usize = Return 32
 let sz_c : usize = eval_global sz_body
 
-(** [array::f5]: forward function
+(** [array::f5]:
     Source: 'src/array.rs', lines 289:0-289:31 *)
 let f5 (x : array u32 32) : result u32 =
   array_index_usize u32 32 x 0
 
-(** [array::ite]: forward function
+(** [array::ite]:
     Source: 'src/array.rs', lines 294:0-294:12 *)
 let ite : result unit =
-  let* s = array_to_slice u32 2 (mk_array u32 2 [ 0; 0 ]) in
-  let* s0 = array_to_slice u32 2 (mk_array u32 2 [ 0; 0 ]) in
-  let* s1 = index_mut_slice_u32_0_back s0 in
-  let* _ = array_from_slice u32 2 (mk_array u32 2 [ 0; 0 ]) s1 in
-  let* s2 = index_mut_slice_u32_0_back s in
-  let* _ = array_from_slice u32 2 (mk_array u32 2 [ 0; 0 ]) s2 in
+  let* (s, to_slice_mut_back) =
+    array_to_slice_mut u32 2 (mk_array u32 2 [ 0; 0 ]) in
+  let* (_, s1) = index_mut_slice_u32_0 s in
+  let* (s2, to_slice_mut_back1) =
+    array_to_slice_mut u32 2 (mk_array u32 2 [ 0; 0 ]) in
+  let* (_, s3) = index_mut_slice_u32_0 s2 in
+  let* _ = to_slice_mut_back1 s3 in
+  let* _ = to_slice_mut_back s1 in
   Return ()
 
diff --git a/tests/fstar/array/Primitives.fst b/tests/fstar/array/Primitives.fst
index a3ffbde4..fca80829 100644
--- a/tests/fstar/array/Primitives.fst
+++ b/tests/fstar/array/Primitives.fst
@@ -55,8 +55,7 @@ type string = string
 let is_zero (n: nat) : bool = n = 0
 let decrease (n: nat{n > 0}) : nat = n - 1
 
-let core_mem_replace (a : Type0) (x : a) (y : a) : a = x
-let core_mem_replace_back (a : Type0) (x : a) (y : a) : a = y
+let core_mem_replace (a : Type0) (x : a) (y : a) : a & a = (x, x)
 
 // We don't really use raw pointers for now
 type mut_raw_ptr (t : Type0) = { v : t }
@@ -477,8 +476,7 @@ noeq type core_ops_index_Index (self idx : Type0) = {
 // Trait declaration: [core::ops::index::IndexMut]
 noeq type core_ops_index_IndexMut (self idx : Type0) = {
   indexInst : core_ops_index_Index self idx;
-  index_mut : self → idx → result indexInst.output;
-  index_mut_back : self → idx → indexInst.output → result self;
+  index_mut : self → idx → result (indexInst.output & (indexInst.output → result self));
 }
 
 // Trait declaration [core::ops::deref::Deref]
@@ -490,8 +488,7 @@ noeq type core_ops_deref_Deref (self : Type0) = {
 // Trait declaration [core::ops::deref::DerefMut]
 noeq type core_ops_deref_DerefMut (self : Type0) = {
   derefInst : core_ops_deref_Deref self;
-  deref_mut : self → result derefInst.target;
-  deref_mut_back : self → derefInst.target → result self;
+  deref_mut : self → result (derefInst.target & (derefInst.target → result self));
 }
 
 type core_ops_range_Range (a : Type0) = {
@@ -502,8 +499,8 @@ type core_ops_range_Range (a : Type0) = {
 (*** [alloc] *)
 
 let alloc_boxed_Box_deref (t : Type0) (x : t) : result t = Return x
-let alloc_boxed_Box_deref_mut (t : Type0) (x : t) : result t = Return x
-let alloc_boxed_Box_deref_mut_back (t : Type) (_ : t) (x : t) : result t = Return x
+let alloc_boxed_Box_deref_mut (t : Type0) (x : t) : result (t & (t -> result t)) =
+  Return (x, (fun x -> Return x))
 
 // Trait instance
 let alloc_boxed_Box_coreopsDerefInst (self : Type0) : core_ops_deref_Deref self = {
@@ -515,7 +512,6 @@ let alloc_boxed_Box_coreopsDerefInst (self : Type0) : core_ops_deref_Deref self
 let alloc_boxed_Box_coreopsDerefMutInst (self : Type0) : core_ops_deref_DerefMut self = {
   derefInst = alloc_boxed_Box_coreopsDerefInst self;
   deref_mut = alloc_boxed_Box_deref_mut self;
-  deref_mut_back = alloc_boxed_Box_deref_mut_back self;
 }
 
 (*** Array *)
@@ -535,10 +531,18 @@ let array_index_usize (a : Type0) (n : usize) (x : array a n) (i : usize) : resu
   if i < length x then Return (index x i)
   else Fail Failure
 
-let array_update_usize (a : Type0) (n : usize) (x : array a n) (i : usize) (nx : a) : result (array a n) =
+let array_update_usize (a : Type0) (n : usize) (x : array a n) (i : usize) (nx : a) :
+  result (array a n) =
   if i < length x then Return (list_update x i nx)
   else Fail Failure
 
+let array_index_mut_usize (a : Type0) (n : usize) (x : array a n) (i : usize) :
+  result (a & (a -> result (array a n))) =
+  match array_index_usize a n x i with
+  | Fail e -> Fail e
+  | Return v ->
+    Return (v, array_update_usize a n x i)
+
 (*** Slice *)
 type slice (a : Type0) = s:list a{length s <= usize_max}
 
@@ -552,6 +556,13 @@ let slice_update_usize (a : Type0) (x : slice a) (i : usize) (nx : a) : result (
   if i < length x then Return (list_update x i nx)
   else Fail Failure
 
+let slice_index_mut_usize (a : Type0) (s : slice a) (i : usize) :
+  result (a & (a -> result (slice a))) =
+  match slice_index_usize a s i with
+  | Fail e -> Fail e
+  | Return x ->
+    Return (x, slice_update_usize a s i)
+
 (*** Subslices *)
 
 let array_to_slice (a : Type0) (n : usize) (x : array a n) : result (slice a) = Return x
@@ -559,6 +570,10 @@ let array_from_slice (a : Type0) (n : usize) (x : array a n) (s : slice a) : res
   if length s = n then Return s
   else Fail Failure
 
+let array_to_slice_mut (a : Type0) (n : usize) (x : array a n) :
+  result (slice a & (slice a -> result (array a n))) =
+  Return (x, array_from_slice a n x)
+
 // TODO: finish the definitions below (there lacks [List.drop] and [List.take] in the standard library *)
 let array_subslice (a : Type0) (n : usize) (x : array a n) (r : core_ops_range_Range usize) : result (slice a) =
   admit()
@@ -588,8 +603,13 @@ let alloc_vec_Vec_index_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) : r
 let alloc_vec_Vec_update_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
   if i < length v then Return (list_update v i x) else Fail Failure
 
-// The **forward** function shouldn't be used
-let alloc_vec_Vec_push_fwd (a  : Type0) (v : alloc_vec_Vec a) (x : a) : unit = ()
+let alloc_vec_Vec_index_mut_usize (#a : Type0) (v: alloc_vec_Vec a) (i: usize) :
+  result (a & (a → result (alloc_vec_Vec a))) =
+  match alloc_vec_Vec_index_usize v i with
+  | Return x ->
+    Return (x, alloc_vec_Vec_update_usize v i)
+  | Fail e -> Fail e
+
 let alloc_vec_Vec_push (a  : Type0) (v : alloc_vec_Vec a) (x : a) :
   Pure (result (alloc_vec_Vec a))
   (requires True)
@@ -605,9 +625,6 @@ let alloc_vec_Vec_push (a  : Type0) (v : alloc_vec_Vec a) (x : a) :
     end
   else Fail Failure
 
-// The **forward** function shouldn't be used
-let alloc_vec_Vec_insert_fwd (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result unit =
-  if i < length v then Return () else Fail Failure
 let alloc_vec_Vec_insert (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
   if i < length v then Return (list_update v i x) else Fail Failure
 
@@ -619,13 +636,11 @@ noeq type core_slice_index_SliceIndex (self t : Type0) = {
   sealedInst : core_slice_index_private_slice_index_Sealed self;
   output : Type0;
   get : self → t → result (option output);
-  get_mut : self → t → result (option output);
-  get_mut_back : self → t → option output → result t;
+  get_mut : self → t → result (option output & (option output -> result t));
   get_unchecked : self → const_raw_ptr t → result (const_raw_ptr output);
   get_unchecked_mut : self → mut_raw_ptr t → result (mut_raw_ptr output);
   index : self → t → result output;
-  index_mut : self → t → result output;
-  index_mut_back : self → t → output → result t;
+  index_mut : self → t → result (output & (output -> result t));
 }
 
 // [core::slice::index::[T]::index]: forward function
@@ -643,14 +658,8 @@ let core_slice_index_RangeUsize_get (t : Type0) (i : core_ops_range_Range usize)
   admit () // TODO
 
 // [core::slice::index::Range::get_mut]: forward function
-let core_slice_index_RangeUsize_get_mut
-  (t : Type0) : core_ops_range_Range usize → slice t → result (option (slice t)) =
-  admit () // TODO
-
-// [core::slice::index::Range::get_mut]: backward function 0
-let core_slice_index_RangeUsize_get_mut_back
-  (t : Type0) :
-  core_ops_range_Range usize → slice t → option (slice t) → result (slice t) =
+let core_slice_index_RangeUsize_get_mut (t : Type0) :
+  core_ops_range_Range usize → slice t → result (option (slice t) & (option (slice t) -> result (slice t))) =
   admit () // TODO
 
 // [core::slice::index::Range::get_unchecked]: forward function
@@ -675,27 +684,16 @@ let core_slice_index_RangeUsize_index
   admit () // TODO
 
 // [core::slice::index::Range::index_mut]: forward function
-let core_slice_index_RangeUsize_index_mut
-  (t : Type0) : core_ops_range_Range usize → slice t → result (slice t) =
-  admit () // TODO
-
-// [core::slice::index::Range::index_mut]: backward function 0
-let core_slice_index_RangeUsize_index_mut_back
-  (t : Type0) : core_ops_range_Range usize → slice t → slice t → result (slice t) =
+let core_slice_index_RangeUsize_index_mut (t : Type0) :
+  core_ops_range_Range usize → slice t → result (slice t & (slice t -> result (slice t))) =
   admit () // TODO
 
 // [core::slice::index::[T]::index_mut]: forward function
 let core_slice_index_Slice_index_mut
   (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
-  slice t → idx → result inst.output =
+  slice t → idx → result (inst.output & (inst.output -> result (slice t))) =
   admit () // 
 
-// [core::slice::index::[T]::index_mut]: backward function 0
-let core_slice_index_Slice_index_mut_back
-  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
-  slice t → idx → inst.output → result (slice t) =
-  admit () // TODO
-
 // [core::array::[T; N]::index]: forward function
 let core_array_Array_index
   (t idx : Type0) (n : usize) (inst : core_ops_index_Index (slice t) idx)
@@ -705,13 +703,8 @@ let core_array_Array_index
 // [core::array::[T; N]::index_mut]: forward function
 let core_array_Array_index_mut
   (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
-  (a : array t n) (i : idx) : result inst.indexInst.output =
-  admit () // TODO
-
-// [core::array::[T; N]::index_mut]: backward function 0
-let core_array_Array_index_mut_back
-  (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
-  (a : array t n) (i : idx) (x : inst.indexInst.output) : result (array t n) =
+  (a : array t n) (i : idx) :
+  result (inst.indexInst.output & (inst.indexInst.output -> result (array t n))) =
   admit () // TODO
 
 // Trait implementation: [core::slice::index::private_slice_index::Range]
@@ -725,12 +718,10 @@ let core_slice_index_SliceIndexRangeUsizeSliceTInst (t : Type0) :
   output = slice t;
   get = core_slice_index_RangeUsize_get t;
   get_mut = core_slice_index_RangeUsize_get_mut t;
-  get_mut_back = core_slice_index_RangeUsize_get_mut_back t;
   get_unchecked = core_slice_index_RangeUsize_get_unchecked t;
   get_unchecked_mut = core_slice_index_RangeUsize_get_unchecked_mut t;
   index = core_slice_index_RangeUsize_index t;
   index_mut = core_slice_index_RangeUsize_index_mut t;
-  index_mut_back = core_slice_index_RangeUsize_index_mut_back t;
 }
 
 // Trait implementation: [core::slice::index::[T]]
@@ -747,7 +738,6 @@ let core_ops_index_IndexMutSliceTIInst (t idx : Type0)
   core_ops_index_IndexMut (slice t) idx = {
   indexInst = core_ops_index_IndexSliceTIInst t idx inst;
   index_mut = core_slice_index_Slice_index_mut t idx inst;
-  index_mut_back = core_slice_index_Slice_index_mut_back t idx inst;
 }
 
 // Trait implementation: [core::array::[T; N]]
@@ -764,7 +754,6 @@ let core_ops_index_IndexMutArrayIInst (t idx : Type0) (n : usize)
   core_ops_index_IndexMut (array t n) idx = {
   indexInst = core_ops_index_IndexArrayInst t idx n inst.indexInst;
   index_mut = core_array_Array_index_mut t idx n inst;
-  index_mut_back = core_array_Array_index_mut_back t idx n inst;
 }
 
 // [core::slice::index::usize::get]: forward function
@@ -773,13 +762,8 @@ let core_slice_index_usize_get
   admit () // TODO
 
 // [core::slice::index::usize::get_mut]: forward function
-let core_slice_index_usize_get_mut
-  (t : Type0) : usize → slice t → result (option t) =
-  admit () // TODO
-
-// [core::slice::index::usize::get_mut]: backward function 0
-let core_slice_index_usize_get_mut_back
-  (t : Type0) : usize → slice t → option t → result (slice t) =
+let core_slice_index_usize_get_mut (t : Type0) :
+  usize → slice t → result (option t & (option t -> result (slice t))) =
   admit () // TODO
 
 // [core::slice::index::usize::get_unchecked]: forward function
@@ -797,12 +781,8 @@ let core_slice_index_usize_index (t : Type0) : usize → slice t → result t =
   admit () // TODO
 
 // [core::slice::index::usize::index_mut]: forward function
-let core_slice_index_usize_index_mut (t : Type0) : usize → slice t → result t =
-  admit () // TODO
-
-// [core::slice::index::usize::index_mut]: backward function 0
-let core_slice_index_usize_index_mut_back
-  (t : Type0) : usize → slice t → t → result (slice t) =
+let core_slice_index_usize_index_mut (t : Type0) :
+  usize → slice t → result (t & (t -> result (slice t))) =
   admit () // TODO
 
 // Trait implementation: [core::slice::index::private_slice_index::usize]
@@ -816,12 +796,10 @@ let core_slice_index_SliceIndexUsizeSliceTInst (t : Type0) :
   output = t;
   get = core_slice_index_usize_get t;
   get_mut = core_slice_index_usize_get_mut t;
-  get_mut_back = core_slice_index_usize_get_mut_back t;
   get_unchecked = core_slice_index_usize_get_unchecked t;
   get_unchecked_mut = core_slice_index_usize_get_unchecked_mut t;
   index = core_slice_index_usize_index t;
   index_mut = core_slice_index_usize_index_mut t;
-  index_mut_back = core_slice_index_usize_index_mut_back t;
 }
 
 // [alloc::vec::Vec::index]: forward function
@@ -831,13 +809,8 @@ let alloc_vec_Vec_index (t idx : Type0) (inst : core_slice_index_SliceIndex idx
 
 // [alloc::vec::Vec::index_mut]: forward function
 let alloc_vec_Vec_index_mut (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
-  (self : alloc_vec_Vec t) (i : idx) : result inst.output =
-  admit () // TODO
-
-// [alloc::vec::Vec::index_mut]: backward function 0
-let alloc_vec_Vec_index_mut_back
-  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
-  (self : alloc_vec_Vec t) (i : idx) (x : inst.output) : result (alloc_vec_Vec t) =
+  (self : alloc_vec_Vec t) (i : idx) :
+  result (inst.output & (inst.output -> result (alloc_vec_Vec t))) =
   admit () // TODO
 
 // Trait implementation: [alloc::vec::Vec]
@@ -854,7 +827,6 @@ let alloc_vec_Vec_coreopsindexIndexMutInst (t idx : Type0)
   core_ops_index_IndexMut (alloc_vec_Vec t) idx = {
   indexInst = alloc_vec_Vec_coreopsindexIndexInst t idx inst;
   index_mut = alloc_vec_Vec_index_mut t idx inst;
-  index_mut_back = alloc_vec_Vec_index_mut_back t idx inst;
 }
 
 (*** Theorems *)
@@ -870,15 +842,7 @@ let alloc_vec_Vec_index_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
 let alloc_vec_Vec_index_mut_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
   Lemma (
     alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i ==
-      alloc_vec_Vec_index_usize v i)
+      alloc_vec_Vec_index_mut_usize v i)
   [SMTPat (alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i)]
   =
   admit()
-
-let alloc_vec_Vec_index_mut_back_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) :
-  Lemma (
-    alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x ==
-      alloc_vec_Vec_update_usize v i x)
-  [SMTPat (alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x)]
-  =
-  admit()
diff --git a/tests/fstar/betree/BetreeMain.Funs.fst b/tests/fstar/betree/BetreeMain.Funs.fst
index f844b0ec..a3065f3d 100644
--- a/tests/fstar/betree/BetreeMain.Funs.fst
+++ b/tests/fstar/betree/BetreeMain.Funs.fst
@@ -8,7 +8,7 @@ include BetreeMain.Clauses
 
 #set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
 
-(** [betree_main::betree::load_internal_node]: forward function
+(** [betree_main::betree::load_internal_node]:
     Source: 'src/betree.rs', lines 36:0-36:52 *)
 let betree_load_internal_node
   (id : u64) (st : state) :
@@ -16,58 +16,48 @@ let betree_load_internal_node
   =
   betree_utils_load_internal_node id st
 
-(** [betree_main::betree::store_internal_node]: forward function
+(** [betree_main::betree::store_internal_node]:
     Source: 'src/betree.rs', lines 41:0-41:60 *)
 let betree_store_internal_node
   (id : u64) (content : betree_List_t (u64 & betree_Message_t)) (st : state) :
   result (state & unit)
   =
-  let* (st0, _) = betree_utils_store_internal_node id content st in
-  Return (st0, ())
+  let* (st1, _) = betree_utils_store_internal_node id content st in
+  Return (st1, ())
 
-(** [betree_main::betree::load_leaf_node]: forward function
+(** [betree_main::betree::load_leaf_node]:
     Source: 'src/betree.rs', lines 46:0-46:44 *)
 let betree_load_leaf_node
   (id : u64) (st : state) : result (state & (betree_List_t (u64 & u64))) =
   betree_utils_load_leaf_node id st
 
-(** [betree_main::betree::store_leaf_node]: forward function
+(** [betree_main::betree::store_leaf_node]:
     Source: 'src/betree.rs', lines 51:0-51:52 *)
 let betree_store_leaf_node
   (id : u64) (content : betree_List_t (u64 & u64)) (st : state) :
   result (state & unit)
   =
-  let* (st0, _) = betree_utils_store_leaf_node id content st in
-  Return (st0, ())
+  let* (st1, _) = betree_utils_store_leaf_node id content st in
+  Return (st1, ())
 
-(** [betree_main::betree::fresh_node_id]: forward function
+(** [betree_main::betree::fresh_node_id]:
     Source: 'src/betree.rs', lines 55:0-55:48 *)
-let betree_fresh_node_id (counter : u64) : result u64 =
-  let* _ = u64_add counter 1 in Return counter
+let betree_fresh_node_id (counter : u64) : result (u64 & u64) =
+  let* counter1 = u64_add counter 1 in Return (counter, counter1)
 
-(** [betree_main::betree::fresh_node_id]: backward function 0
-    Source: 'src/betree.rs', lines 55:0-55:48 *)
-let betree_fresh_node_id_back (counter : u64) : result u64 =
-  u64_add counter 1
-
-(** [betree_main::betree::{betree_main::betree::NodeIdCounter}::new]: forward function
+(** [betree_main::betree::{betree_main::betree::NodeIdCounter}::new]:
     Source: 'src/betree.rs', lines 206:4-206:20 *)
 let betree_NodeIdCounter_new : result betree_NodeIdCounter_t =
   Return { next_node_id = 0 }
 
-(** [betree_main::betree::{betree_main::betree::NodeIdCounter}::fresh_id]: forward function
+(** [betree_main::betree::{betree_main::betree::NodeIdCounter}::fresh_id]:
     Source: 'src/betree.rs', lines 210:4-210:36 *)
 let betree_NodeIdCounter_fresh_id
-  (self : betree_NodeIdCounter_t) : result u64 =
-  let* _ = u64_add self.next_node_id 1 in Return self.next_node_id
-
-(** [betree_main::betree::{betree_main::betree::NodeIdCounter}::fresh_id]: backward function 0
-    Source: 'src/betree.rs', lines 210:4-210:36 *)
-let betree_NodeIdCounter_fresh_id_back
-  (self : betree_NodeIdCounter_t) : result betree_NodeIdCounter_t =
-  let* i = u64_add self.next_node_id 1 in Return { next_node_id = i }
+  (self : betree_NodeIdCounter_t) : result (u64 & betree_NodeIdCounter_t) =
+  let* i = u64_add self.next_node_id 1 in
+  Return (self.next_node_id, { next_node_id = i })
 
-(** [betree_main::betree::upsert_update]: forward function
+(** [betree_main::betree::upsert_update]:
     Source: 'src/betree.rs', lines 234:0-234:70 *)
 let betree_upsert_update
   (prev : option u64) (st : betree_UpsertFunState_t) : result u64 =
@@ -75,30 +65,30 @@ let betree_upsert_update
   | None ->
     begin match st with
     | Betree_UpsertFunState_Add v -> Return v
-    | Betree_UpsertFunState_Sub i -> Return 0
+    | Betree_UpsertFunState_Sub _ -> Return 0
     end
-  | Some prev0 ->
+  | Some prev1 ->
     begin match st with
     | Betree_UpsertFunState_Add v ->
-      let* margin = u64_sub core_u64_max prev0 in
-      if margin >= v then u64_add prev0 v else Return core_u64_max
+      let* margin = u64_sub core_u64_max prev1 in
+      if margin >= v then u64_add prev1 v else Return core_u64_max
     | Betree_UpsertFunState_Sub v ->
-      if prev0 >= v then u64_sub prev0 v else Return 0
+      if prev1 >= v then u64_sub prev1 v else Return 0
     end
   end
 
-(** [betree_main::betree::{betree_main::betree::List<T>#1}::len]: forward function
+(** [betree_main::betree::{betree_main::betree::List<T>#1}::len]:
     Source: 'src/betree.rs', lines 276:4-276:24 *)
 let rec betree_List_len
   (t : Type0) (self : betree_List_t t) :
   Tot (result u64) (decreases (betree_List_len_decreases t self))
   =
   begin match self with
-  | Betree_List_Cons x tl -> let* i = betree_List_len t tl in u64_add 1 i
+  | Betree_List_Cons _ tl -> let* i = betree_List_len t tl in u64_add 1 i
   | Betree_List_Nil -> Return 0
   end
 
-(** [betree_main::betree::{betree_main::betree::List<T>#1}::split_at]: forward function
+(** [betree_main::betree::{betree_main::betree::List<T>#1}::split_at]:
     Source: 'src/betree.rs', lines 284:4-284:51 *)
 let rec betree_List_split_at
   (t : Type0) (self : betree_List_t t) (n : u64) :
@@ -118,52 +108,42 @@ let rec betree_List_split_at
     | Betree_List_Nil -> Fail Failure
     end
 
-(** [betree_main::betree::{betree_main::betree::List<T>#1}::push_front]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [betree_main::betree::{betree_main::betree::List<T>#1}::push_front]:
     Source: 'src/betree.rs', lines 299:4-299:34 *)
 let betree_List_push_front
   (t : Type0) (self : betree_List_t t) (x : t) : result (betree_List_t t) =
-  let tl = core_mem_replace (betree_List_t t) self Betree_List_Nil in
+  let (tl, _) = core_mem_replace (betree_List_t t) self Betree_List_Nil in
   let l = tl in
   Return (Betree_List_Cons x l)
 
-(** [betree_main::betree::{betree_main::betree::List<T>#1}::pop_front]: forward function
-    Source: 'src/betree.rs', lines 306:4-306:32 *)
-let betree_List_pop_front (t : Type0) (self : betree_List_t t) : result t =
-  let ls = core_mem_replace (betree_List_t t) self Betree_List_Nil in
-  begin match ls with
-  | Betree_List_Cons x tl -> Return x
-  | Betree_List_Nil -> Fail Failure
-  end
-
-(** [betree_main::betree::{betree_main::betree::List<T>#1}::pop_front]: backward function 0
+(** [betree_main::betree::{betree_main::betree::List<T>#1}::pop_front]:
     Source: 'src/betree.rs', lines 306:4-306:32 *)
-let betree_List_pop_front_back
-  (t : Type0) (self : betree_List_t t) : result (betree_List_t t) =
-  let ls = core_mem_replace (betree_List_t t) self Betree_List_Nil in
+let betree_List_pop_front
+  (t : Type0) (self : betree_List_t t) : result (t & (betree_List_t t)) =
+  let (ls, _) = core_mem_replace (betree_List_t t) self Betree_List_Nil in
   begin match ls with
-  | Betree_List_Cons x tl -> Return tl
+  | Betree_List_Cons x tl -> Return (x, tl)
   | Betree_List_Nil -> Fail Failure
   end
 
-(** [betree_main::betree::{betree_main::betree::List<T>#1}::hd]: forward function
+(** [betree_main::betree::{betree_main::betree::List<T>#1}::hd]:
     Source: 'src/betree.rs', lines 318:4-318:22 *)
 let betree_List_hd (t : Type0) (self : betree_List_t t) : result t =
   begin match self with
-  | Betree_List_Cons hd l -> Return hd
+  | Betree_List_Cons hd _ -> Return hd
   | Betree_List_Nil -> Fail Failure
   end
 
-(** [betree_main::betree::{betree_main::betree::List<(u64, T)>#2}::head_has_key]: forward function
+(** [betree_main::betree::{betree_main::betree::List<(u64, T)>#2}::head_has_key]:
     Source: 'src/betree.rs', lines 327:4-327:44 *)
 let betree_ListTupleU64T_head_has_key
   (t : Type0) (self : betree_List_t (u64 & t)) (key : u64) : result bool =
   begin match self with
-  | Betree_List_Cons hd l -> let (i, _) = hd in Return (i = key)
+  | Betree_List_Cons hd _ -> let (i, _) = hd in Return (i = key)
   | Betree_List_Nil -> Return false
   end
 
-(** [betree_main::betree::{betree_main::betree::List<(u64, T)>#2}::partition_at_pivot]: forward function
+(** [betree_main::betree::{betree_main::betree::List<(u64, T)>#2}::partition_at_pivot]:
     Source: 'src/betree.rs', lines 339:4-339:73 *)
 let rec betree_ListTupleU64T_partition_at_pivot
   (t : Type0) (self : betree_List_t (u64 & t)) (pivot : u64) :
@@ -183,82 +163,54 @@ let rec betree_ListTupleU64T_partition_at_pivot
   | Betree_List_Nil -> Return (Betree_List_Nil, Betree_List_Nil)
   end
 
-(** [betree_main::betree::{betree_main::betree::Leaf#3}::split]: forward function
+(** [betree_main::betree::{betree_main::betree::Leaf#3}::split]:
     Source: 'src/betree.rs', lines 359:4-364:17 *)
 let betree_Leaf_split
   (self : betree_Leaf_t) (content : betree_List_t (u64 & u64))
   (params : betree_Params_t) (node_id_cnt : betree_NodeIdCounter_t)
   (st : state) :
-  result (state & betree_Internal_t)
+  result (state & (betree_Internal_t & betree_NodeIdCounter_t))
   =
   let* p = betree_List_split_at (u64 & u64) content params.split_size in
   let (content0, content1) = p in
-  let* p0 = betree_List_hd (u64 & u64) content1 in
-  let (pivot, _) = p0 in
-  let* id0 = betree_NodeIdCounter_fresh_id node_id_cnt in
-  let* node_id_cnt0 = betree_NodeIdCounter_fresh_id_back node_id_cnt in
-  let* id1 = betree_NodeIdCounter_fresh_id node_id_cnt0 in
-  let* (st0, _) = betree_store_leaf_node id0 content0 st in
-  let* (st1, _) = betree_store_leaf_node id1 content1 st0 in
+  let* p1 = betree_List_hd (u64 & u64) content1 in
+  let (pivot, _) = p1 in
+  let* (id0, nic) = betree_NodeIdCounter_fresh_id node_id_cnt in
+  let* (id1, nic1) = betree_NodeIdCounter_fresh_id nic in
+  let* (st1, _) = betree_store_leaf_node id0 content0 st in
+  let* (st2, _) = betree_store_leaf_node id1 content1 st1 in
   let n = Betree_Node_Leaf { id = id0; size = params.split_size } in
-  let n0 = Betree_Node_Leaf { id = id1; size = params.split_size } in
-  Return (st1, { id = self.id; pivot = pivot; left = n; right = n0 })
+  let n1 = Betree_Node_Leaf { id = id1; size = params.split_size } in
+  Return (st2, ({ id = self.id; pivot = pivot; left = n; right = n1 }, nic1))
 
-(** [betree_main::betree::{betree_main::betree::Leaf#3}::split]: backward function 2
-    Source: 'src/betree.rs', lines 359:4-364:17 *)
-let betree_Leaf_split_back
-  (self : betree_Leaf_t) (content : betree_List_t (u64 & u64))
-  (params : betree_Params_t) (node_id_cnt : betree_NodeIdCounter_t)
-  (st : state) :
-  result betree_NodeIdCounter_t
-  =
-  let* p = betree_List_split_at (u64 & u64) content params.split_size in
-  let (content0, content1) = p in
-  let* _ = betree_List_hd (u64 & u64) content1 in
-  let* id0 = betree_NodeIdCounter_fresh_id node_id_cnt in
-  let* node_id_cnt0 = betree_NodeIdCounter_fresh_id_back node_id_cnt in
-  let* id1 = betree_NodeIdCounter_fresh_id node_id_cnt0 in
-  let* (st0, _) = betree_store_leaf_node id0 content0 st in
-  let* _ = betree_store_leaf_node id1 content1 st0 in
-  betree_NodeIdCounter_fresh_id_back node_id_cnt0
-
-(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_first_message_for_key]: forward function
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_first_message_for_key]:
     Source: 'src/betree.rs', lines 789:4-792:34 *)
 let rec betree_Node_lookup_first_message_for_key
   (key : u64) (msgs : betree_List_t (u64 & betree_Message_t)) :
-  Tot (result (betree_List_t (u64 & betree_Message_t)))
-  (decreases (betree_Node_lookup_first_message_for_key_decreases key msgs))
-  =
-  begin match msgs with
-  | Betree_List_Cons x next_msgs ->
-    let (i, m) = x in
-    if i >= key
-    then Return (Betree_List_Cons (i, m) next_msgs)
-    else betree_Node_lookup_first_message_for_key key next_msgs
-  | Betree_List_Nil -> Return Betree_List_Nil
-  end
-
-(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_first_message_for_key]: backward function 0
-    Source: 'src/betree.rs', lines 789:4-792:34 *)
-let rec betree_Node_lookup_first_message_for_key_back
-  (key : u64) (msgs : betree_List_t (u64 & betree_Message_t))
-  (ret : betree_List_t (u64 & betree_Message_t)) :
-  Tot (result (betree_List_t (u64 & betree_Message_t)))
+  Tot (result ((betree_List_t (u64 & betree_Message_t)) & (betree_List_t (u64 &
+    betree_Message_t) -> result (betree_List_t (u64 & betree_Message_t)))))
   (decreases (betree_Node_lookup_first_message_for_key_decreases key msgs))
   =
   begin match msgs with
   | Betree_List_Cons x next_msgs ->
     let (i, m) = x in
     if i >= key
-    then Return ret
+    then
+      let back_'a = fun ret -> Return ret in
+      Return (Betree_List_Cons (i, m) next_msgs, back_'a)
     else
-      let* next_msgs0 =
-        betree_Node_lookup_first_message_for_key_back key next_msgs ret in
-      Return (Betree_List_Cons (i, m) next_msgs0)
-  | Betree_List_Nil -> Return ret
+      let* (l, lookup_first_message_for_key_back) =
+        betree_Node_lookup_first_message_for_key key next_msgs in
+      let back_'a =
+        fun ret ->
+          let* next_msgs1 = lookup_first_message_for_key_back ret in
+          Return (Betree_List_Cons (i, m) next_msgs1) in
+      Return (l, back_'a)
+  | Betree_List_Nil ->
+    let back_'a = fun ret -> Return ret in Return (Betree_List_Nil, back_'a)
   end
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_in_bindings]: forward function
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_in_bindings]:
     Source: 'src/betree.rs', lines 636:4-636:80 *)
 let rec betree_Node_lookup_in_bindings
   (key : u64) (bindings : betree_List_t (u64 & u64)) :
@@ -267,215 +219,110 @@ let rec betree_Node_lookup_in_bindings
   =
   begin match bindings with
   | Betree_List_Cons hd tl ->
-    let (i, i0) = hd in
+    let (i, i1) = hd in
     if i = key
-    then Return (Some i0)
+    then Return (Some i1)
     else if i > key then Return None else betree_Node_lookup_in_bindings key tl
   | Betree_List_Nil -> Return None
   end
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply_upserts]: forward function
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_upserts]:
     Source: 'src/betree.rs', lines 819:4-819:90 *)
 let rec betree_Node_apply_upserts
   (msgs : betree_List_t (u64 & betree_Message_t)) (prev : option u64)
   (key : u64) (st : state) :
-  Tot (result (state & u64))
+  Tot (result (state & (u64 & (betree_List_t (u64 & betree_Message_t)))))
   (decreases (betree_Node_apply_upserts_decreases msgs prev key st))
   =
   let* b = betree_ListTupleU64T_head_has_key betree_Message_t msgs key in
   if b
   then
-    let* msg = betree_List_pop_front (u64 & betree_Message_t) msgs in
+    let* (msg, l) = betree_List_pop_front (u64 & betree_Message_t) msgs in
     let (_, m) = msg in
     begin match m with
-    | Betree_Message_Insert i -> Fail Failure
+    | Betree_Message_Insert _ -> Fail Failure
     | Betree_Message_Delete -> Fail Failure
     | Betree_Message_Upsert s ->
       let* v = betree_upsert_update prev s in
-      let* msgs0 = betree_List_pop_front_back (u64 & betree_Message_t) msgs in
-      betree_Node_apply_upserts msgs0 (Some v) key st
+      betree_Node_apply_upserts l (Some v) key st
     end
   else
-    let* (st0, v) = core_option_Option_unwrap u64 prev st in
-    let* _ =
+    let* (st1, v) = core_option_Option_unwrap u64 prev st in
+    let* l =
       betree_List_push_front (u64 & betree_Message_t) msgs (key,
         Betree_Message_Insert v) in
-    Return (st0, v)
-
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply_upserts]: backward function 0
-    Source: 'src/betree.rs', lines 819:4-819:90 *)
-let rec betree_Node_apply_upserts_back
-  (msgs : betree_List_t (u64 & betree_Message_t)) (prev : option u64)
-  (key : u64) (st : state) :
-  Tot (result (betree_List_t (u64 & betree_Message_t)))
-  (decreases (betree_Node_apply_upserts_decreases msgs prev key st))
-  =
-  let* b = betree_ListTupleU64T_head_has_key betree_Message_t msgs key in
-  if b
-  then
-    let* msg = betree_List_pop_front (u64 & betree_Message_t) msgs in
-    let (_, m) = msg in
-    begin match m with
-    | Betree_Message_Insert i -> Fail Failure
-    | Betree_Message_Delete -> Fail Failure
-    | Betree_Message_Upsert s ->
-      let* v = betree_upsert_update prev s in
-      let* msgs0 = betree_List_pop_front_back (u64 & betree_Message_t) msgs in
-      betree_Node_apply_upserts_back msgs0 (Some v) key st
-    end
-  else
-    let* (_, v) = core_option_Option_unwrap u64 prev st in
-    betree_List_push_front (u64 & betree_Message_t) msgs (key,
-      Betree_Message_Insert v)
+    Return (st1, (v, l))
 
-(** [betree_main::betree::{betree_main::betree::Internal#4}::lookup_in_children]: forward function
+(** [betree_main::betree::{betree_main::betree::Internal#4}::lookup_in_children]:
     Source: 'src/betree.rs', lines 395:4-395:63 *)
 let rec betree_Internal_lookup_in_children
   (self : betree_Internal_t) (key : u64) (st : state) :
-  Tot (result (state & (option u64)))
-  (decreases (betree_Internal_lookup_in_children_decreases self key st))
-  =
-  if key < self.pivot
-  then betree_Node_lookup self.left key st
-  else betree_Node_lookup self.right key st
-
-(** [betree_main::betree::{betree_main::betree::Internal#4}::lookup_in_children]: backward function 0
-    Source: 'src/betree.rs', lines 395:4-395:63 *)
-and betree_Internal_lookup_in_children_back
-  (self : betree_Internal_t) (key : u64) (st : state) :
-  Tot (result betree_Internal_t)
+  Tot (result (state & ((option u64) & betree_Internal_t)))
   (decreases (betree_Internal_lookup_in_children_decreases self key st))
   =
   if key < self.pivot
   then
-    let* n = betree_Node_lookup_back self.left key st in
-    Return { self with left = n }
+    let* (st1, (o, n)) = betree_Node_lookup self.left key st in
+    Return (st1, (o, { self with left = n }))
   else
-    let* n = betree_Node_lookup_back self.right key st in
-    Return { self with right = n }
+    let* (st1, (o, n)) = betree_Node_lookup self.right key st in
+    Return (st1, (o, { self with right = n }))
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::lookup]: forward function
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup]:
     Source: 'src/betree.rs', lines 709:4-709:58 *)
 and betree_Node_lookup
   (self : betree_Node_t) (key : u64) (st : state) :
-  Tot (result (state & (option u64)))
+  Tot (result (state & ((option u64) & betree_Node_t)))
   (decreases (betree_Node_lookup_decreases self key st))
   =
   begin match self with
   | Betree_Node_Internal node ->
-    let* (st0, msgs) = betree_load_internal_node node.id st in
-    let* pending = betree_Node_lookup_first_message_for_key key msgs in
+    let* (st1, msgs) = betree_load_internal_node node.id st in
+    let* (pending, lookup_first_message_for_key_back) =
+      betree_Node_lookup_first_message_for_key key msgs in
     begin match pending with
     | Betree_List_Cons p l ->
       let (k, msg) = p in
       if k <> key
       then
-        let* (st1, o) = betree_Internal_lookup_in_children node key st0 in
+        let* (st2, (o, i)) = betree_Internal_lookup_in_children node key st1 in
         let* _ =
-          betree_Node_lookup_first_message_for_key_back key msgs
-            (Betree_List_Cons (k, msg) l) in
-        Return (st1, o)
+          lookup_first_message_for_key_back (Betree_List_Cons (k, msg) l) in
+        Return (st2, (o, Betree_Node_Internal i))
       else
         begin match msg with
         | Betree_Message_Insert v ->
           let* _ =
-            betree_Node_lookup_first_message_for_key_back key msgs
-              (Betree_List_Cons (k, Betree_Message_Insert v) l) in
-          Return (st0, Some v)
+            lookup_first_message_for_key_back (Betree_List_Cons (k,
+              Betree_Message_Insert v) l) in
+          Return (st1, (Some v, Betree_Node_Internal node))
         | Betree_Message_Delete ->
           let* _ =
-            betree_Node_lookup_first_message_for_key_back key msgs
-              (Betree_List_Cons (k, Betree_Message_Delete) l) in
-          Return (st0, None)
+            lookup_first_message_for_key_back (Betree_List_Cons (k,
+              Betree_Message_Delete) l) in
+          Return (st1, (None, Betree_Node_Internal node))
         | Betree_Message_Upsert ufs ->
-          let* (st1, v) = betree_Internal_lookup_in_children node key st0 in
-          let* (st2, v0) =
+          let* (st2, (v, i)) = betree_Internal_lookup_in_children node key st1
+            in
+          let* (st3, (v1, l1)) =
             betree_Node_apply_upserts (Betree_List_Cons (k,
-              Betree_Message_Upsert ufs) l) v key st1 in
-          let* node0 = betree_Internal_lookup_in_children_back node key st0 in
-          let* pending0 =
-            betree_Node_apply_upserts_back (Betree_List_Cons (k,
-              Betree_Message_Upsert ufs) l) v key st1 in
-          let* msgs0 =
-            betree_Node_lookup_first_message_for_key_back key msgs pending0 in
-          let* (st3, _) = betree_store_internal_node node0.id msgs0 st2 in
-          Return (st3, Some v0)
+              Betree_Message_Upsert ufs) l) v key st2 in
+          let* msgs1 = lookup_first_message_for_key_back l1 in
+          let* (st4, _) = betree_store_internal_node i.id msgs1 st3 in
+          Return (st4, (Some v1, Betree_Node_Internal i))
         end
     | Betree_List_Nil ->
-      let* (st1, o) = betree_Internal_lookup_in_children node key st0 in
-      let* _ =
-        betree_Node_lookup_first_message_for_key_back key msgs Betree_List_Nil
-        in
-      Return (st1, o)
+      let* (st2, (o, i)) = betree_Internal_lookup_in_children node key st1 in
+      let* _ = lookup_first_message_for_key_back Betree_List_Nil in
+      Return (st2, (o, Betree_Node_Internal i))
     end
   | Betree_Node_Leaf node ->
-    let* (st0, bindings) = betree_load_leaf_node node.id st in
+    let* (st1, bindings) = betree_load_leaf_node node.id st in
     let* o = betree_Node_lookup_in_bindings key bindings in
-    Return (st0, o)
+    Return (st1, (o, Betree_Node_Leaf node))
   end
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::lookup]: backward function 0
-    Source: 'src/betree.rs', lines 709:4-709:58 *)
-and betree_Node_lookup_back
-  (self : betree_Node_t) (key : u64) (st : state) :
-  Tot (result betree_Node_t)
-  (decreases (betree_Node_lookup_decreases self key st))
-  =
-  begin match self with
-  | Betree_Node_Internal node ->
-    let* (st0, msgs) = betree_load_internal_node node.id st in
-    let* pending = betree_Node_lookup_first_message_for_key key msgs in
-    begin match pending with
-    | Betree_List_Cons p l ->
-      let (k, msg) = p in
-      if k <> key
-      then
-        let* _ =
-          betree_Node_lookup_first_message_for_key_back key msgs
-            (Betree_List_Cons (k, msg) l) in
-        let* node0 = betree_Internal_lookup_in_children_back node key st0 in
-        Return (Betree_Node_Internal node0)
-      else
-        begin match msg with
-        | Betree_Message_Insert v ->
-          let* _ =
-            betree_Node_lookup_first_message_for_key_back key msgs
-              (Betree_List_Cons (k, Betree_Message_Insert v) l) in
-          Return (Betree_Node_Internal node)
-        | Betree_Message_Delete ->
-          let* _ =
-            betree_Node_lookup_first_message_for_key_back key msgs
-              (Betree_List_Cons (k, Betree_Message_Delete) l) in
-          Return (Betree_Node_Internal node)
-        | Betree_Message_Upsert ufs ->
-          let* (st1, v) = betree_Internal_lookup_in_children node key st0 in
-          let* (st2, _) =
-            betree_Node_apply_upserts (Betree_List_Cons (k,
-              Betree_Message_Upsert ufs) l) v key st1 in
-          let* node0 = betree_Internal_lookup_in_children_back node key st0 in
-          let* pending0 =
-            betree_Node_apply_upserts_back (Betree_List_Cons (k,
-              Betree_Message_Upsert ufs) l) v key st1 in
-          let* msgs0 =
-            betree_Node_lookup_first_message_for_key_back key msgs pending0 in
-          let* _ = betree_store_internal_node node0.id msgs0 st2 in
-          Return (Betree_Node_Internal node0)
-        end
-    | Betree_List_Nil ->
-      let* _ =
-        betree_Node_lookup_first_message_for_key_back key msgs Betree_List_Nil
-        in
-      let* node0 = betree_Internal_lookup_in_children_back node key st0 in
-      Return (Betree_Node_Internal node0)
-    end
-  | Betree_Node_Leaf node ->
-    let* (_, bindings) = betree_load_leaf_node node.id st in
-    let* _ = betree_Node_lookup_in_bindings key bindings in
-    Return (Betree_Node_Leaf node)
-  end
-
-(** [betree_main::betree::{betree_main::betree::Node#5}::filter_messages_for_key]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [betree_main::betree::{betree_main::betree::Node#5}::filter_messages_for_key]:
     Source: 'src/betree.rs', lines 674:4-674:77 *)
 let rec betree_Node_filter_messages_for_key
   (key : u64) (msgs : betree_List_t (u64 & betree_Message_t)) :
@@ -487,36 +334,20 @@ let rec betree_Node_filter_messages_for_key
     let (k, m) = p in
     if k = key
     then
-      let* msgs0 =
-        betree_List_pop_front_back (u64 & betree_Message_t) (Betree_List_Cons
-          (k, m) l) in
-      betree_Node_filter_messages_for_key key msgs0
+      let* (_, l1) =
+        betree_List_pop_front (u64 & betree_Message_t) (Betree_List_Cons (k, m)
+          l) in
+      betree_Node_filter_messages_for_key key l1
     else Return (Betree_List_Cons (k, m) l)
   | Betree_List_Nil -> Return Betree_List_Nil
   end
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_first_message_after_key]: forward function
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_first_message_after_key]:
     Source: 'src/betree.rs', lines 689:4-692:34 *)
 let rec betree_Node_lookup_first_message_after_key
   (key : u64) (msgs : betree_List_t (u64 & betree_Message_t)) :
-  Tot (result (betree_List_t (u64 & betree_Message_t)))
-  (decreases (betree_Node_lookup_first_message_after_key_decreases key msgs))
-  =
-  begin match msgs with
-  | Betree_List_Cons p next_msgs ->
-    let (k, m) = p in
-    if k = key
-    then betree_Node_lookup_first_message_after_key key next_msgs
-    else Return (Betree_List_Cons (k, m) next_msgs)
-  | Betree_List_Nil -> Return Betree_List_Nil
-  end
-
-(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_first_message_after_key]: backward function 0
-    Source: 'src/betree.rs', lines 689:4-692:34 *)
-let rec betree_Node_lookup_first_message_after_key_back
-  (key : u64) (msgs : betree_List_t (u64 & betree_Message_t))
-  (ret : betree_List_t (u64 & betree_Message_t)) :
-  Tot (result (betree_List_t (u64 & betree_Message_t)))
+  Tot (result ((betree_List_t (u64 & betree_Message_t)) & (betree_List_t (u64 &
+    betree_Message_t) -> result (betree_List_t (u64 & betree_Message_t)))))
   (decreases (betree_Node_lookup_first_message_after_key_decreases key msgs))
   =
   begin match msgs with
@@ -524,75 +355,79 @@ let rec betree_Node_lookup_first_message_after_key_back
     let (k, m) = p in
     if k = key
     then
-      let* next_msgs0 =
-        betree_Node_lookup_first_message_after_key_back key next_msgs ret in
-      Return (Betree_List_Cons (k, m) next_msgs0)
-    else Return ret
-  | Betree_List_Nil -> Return ret
+      let* (l, lookup_first_message_after_key_back) =
+        betree_Node_lookup_first_message_after_key key next_msgs in
+      let back_'a =
+        fun ret ->
+          let* next_msgs1 = lookup_first_message_after_key_back ret in
+          Return (Betree_List_Cons (k, m) next_msgs1) in
+      Return (l, back_'a)
+    else
+      let back_'a = fun ret -> Return ret in
+      Return (Betree_List_Cons (k, m) next_msgs, back_'a)
+  | Betree_List_Nil ->
+    let back_'a = fun ret -> Return ret in Return (Betree_List_Nil, back_'a)
   end
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply_to_internal]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_to_internal]:
     Source: 'src/betree.rs', lines 521:4-521:89 *)
 let betree_Node_apply_to_internal
   (msgs : betree_List_t (u64 & betree_Message_t)) (key : u64)
   (new_msg : betree_Message_t) :
   result (betree_List_t (u64 & betree_Message_t))
   =
-  let* msgs0 = betree_Node_lookup_first_message_for_key key msgs in
-  let* b = betree_ListTupleU64T_head_has_key betree_Message_t msgs0 key in
+  let* (msgs1, lookup_first_message_for_key_back) =
+    betree_Node_lookup_first_message_for_key key msgs in
+  let* b = betree_ListTupleU64T_head_has_key betree_Message_t msgs1 key in
   if b
   then
     begin match new_msg with
     | Betree_Message_Insert i ->
-      let* msgs1 = betree_Node_filter_messages_for_key key msgs0 in
-      let* msgs2 =
-        betree_List_push_front (u64 & betree_Message_t) msgs1 (key,
+      let* l = betree_Node_filter_messages_for_key key msgs1 in
+      let* l1 =
+        betree_List_push_front (u64 & betree_Message_t) l (key,
           Betree_Message_Insert i) in
-      betree_Node_lookup_first_message_for_key_back key msgs msgs2
+      lookup_first_message_for_key_back l1
     | Betree_Message_Delete ->
-      let* msgs1 = betree_Node_filter_messages_for_key key msgs0 in
-      let* msgs2 =
-        betree_List_push_front (u64 & betree_Message_t) msgs1 (key,
+      let* l = betree_Node_filter_messages_for_key key msgs1 in
+      let* l1 =
+        betree_List_push_front (u64 & betree_Message_t) l (key,
           Betree_Message_Delete) in
-      betree_Node_lookup_first_message_for_key_back key msgs msgs2
+      lookup_first_message_for_key_back l1
     | Betree_Message_Upsert s ->
-      let* p = betree_List_hd (u64 & betree_Message_t) msgs0 in
+      let* p = betree_List_hd (u64 & betree_Message_t) msgs1 in
       let (_, m) = p in
       begin match m with
       | Betree_Message_Insert prev ->
         let* v = betree_upsert_update (Some prev) s in
-        let* msgs1 = betree_List_pop_front_back (u64 & betree_Message_t) msgs0
-          in
-        let* msgs2 =
-          betree_List_push_front (u64 & betree_Message_t) msgs1 (key,
+        let* (_, l) = betree_List_pop_front (u64 & betree_Message_t) msgs1 in
+        let* l1 =
+          betree_List_push_front (u64 & betree_Message_t) l (key,
             Betree_Message_Insert v) in
-        betree_Node_lookup_first_message_for_key_back key msgs msgs2
+        lookup_first_message_for_key_back l1
       | Betree_Message_Delete ->
+        let* (_, l) = betree_List_pop_front (u64 & betree_Message_t) msgs1 in
         let* v = betree_upsert_update None s in
-        let* msgs1 = betree_List_pop_front_back (u64 & betree_Message_t) msgs0
-          in
-        let* msgs2 =
-          betree_List_push_front (u64 & betree_Message_t) msgs1 (key,
+        let* l1 =
+          betree_List_push_front (u64 & betree_Message_t) l (key,
             Betree_Message_Insert v) in
-        betree_Node_lookup_first_message_for_key_back key msgs msgs2
-      | Betree_Message_Upsert ufs ->
-        let* msgs1 = betree_Node_lookup_first_message_after_key key msgs0 in
-        let* msgs2 =
-          betree_List_push_front (u64 & betree_Message_t) msgs1 (key,
+        lookup_first_message_for_key_back l1
+      | Betree_Message_Upsert _ ->
+        let* (msgs2, lookup_first_message_after_key_back) =
+          betree_Node_lookup_first_message_after_key key msgs1 in
+        let* l =
+          betree_List_push_front (u64 & betree_Message_t) msgs2 (key,
             Betree_Message_Upsert s) in
-        let* msgs3 =
-          betree_Node_lookup_first_message_after_key_back key msgs0 msgs2 in
-        betree_Node_lookup_first_message_for_key_back key msgs msgs3
+        let* msgs3 = lookup_first_message_after_key_back l in
+        lookup_first_message_for_key_back msgs3
       end
     end
   else
-    let* msgs1 =
-      betree_List_push_front (u64 & betree_Message_t) msgs0 (key, new_msg) in
-    betree_Node_lookup_first_message_for_key_back key msgs msgs1
+    let* l =
+      betree_List_push_front (u64 & betree_Message_t) msgs1 (key, new_msg) in
+    lookup_first_message_for_key_back l
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages_to_internal]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages_to_internal]:
     Source: 'src/betree.rs', lines 502:4-505:5 *)
 let rec betree_Node_apply_messages_to_internal
   (msgs : betree_List_t (u64 & betree_Message_t))
@@ -603,89 +438,75 @@ let rec betree_Node_apply_messages_to_internal
   begin match new_msgs with
   | Betree_List_Cons new_msg new_msgs_tl ->
     let (i, m) = new_msg in
-    let* msgs0 = betree_Node_apply_to_internal msgs i m in
-    betree_Node_apply_messages_to_internal msgs0 new_msgs_tl
+    let* l = betree_Node_apply_to_internal msgs i m in
+    betree_Node_apply_messages_to_internal l new_msgs_tl
   | Betree_List_Nil -> Return msgs
   end
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_mut_in_bindings]: forward function
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_mut_in_bindings]:
     Source: 'src/betree.rs', lines 653:4-656:32 *)
 let rec betree_Node_lookup_mut_in_bindings
   (key : u64) (bindings : betree_List_t (u64 & u64)) :
-  Tot (result (betree_List_t (u64 & u64)))
-  (decreases (betree_Node_lookup_mut_in_bindings_decreases key bindings))
-  =
-  begin match bindings with
-  | Betree_List_Cons hd tl ->
-    let (i, i0) = hd in
-    if i >= key
-    then Return (Betree_List_Cons (i, i0) tl)
-    else betree_Node_lookup_mut_in_bindings key tl
-  | Betree_List_Nil -> Return Betree_List_Nil
-  end
-
-(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_mut_in_bindings]: backward function 0
-    Source: 'src/betree.rs', lines 653:4-656:32 *)
-let rec betree_Node_lookup_mut_in_bindings_back
-  (key : u64) (bindings : betree_List_t (u64 & u64))
-  (ret : betree_List_t (u64 & u64)) :
-  Tot (result (betree_List_t (u64 & u64)))
+  Tot (result ((betree_List_t (u64 & u64)) & (betree_List_t (u64 & u64) ->
+    result (betree_List_t (u64 & u64)))))
   (decreases (betree_Node_lookup_mut_in_bindings_decreases key bindings))
   =
   begin match bindings with
   | Betree_List_Cons hd tl ->
-    let (i, i0) = hd in
+    let (i, i1) = hd in
     if i >= key
-    then Return ret
+    then
+      let back_'a = fun ret -> Return ret in
+      Return (Betree_List_Cons (i, i1) tl, back_'a)
     else
-      let* tl0 = betree_Node_lookup_mut_in_bindings_back key tl ret in
-      Return (Betree_List_Cons (i, i0) tl0)
-  | Betree_List_Nil -> Return ret
+      let* (l, lookup_mut_in_bindings_back) =
+        betree_Node_lookup_mut_in_bindings key tl in
+      let back_'a =
+        fun ret ->
+          let* tl1 = lookup_mut_in_bindings_back ret in
+          Return (Betree_List_Cons (i, i1) tl1) in
+      Return (l, back_'a)
+  | Betree_List_Nil ->
+    let back_'a = fun ret -> Return ret in Return (Betree_List_Nil, back_'a)
   end
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply_to_leaf]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_to_leaf]:
     Source: 'src/betree.rs', lines 460:4-460:87 *)
 let betree_Node_apply_to_leaf
   (bindings : betree_List_t (u64 & u64)) (key : u64)
   (new_msg : betree_Message_t) :
   result (betree_List_t (u64 & u64))
   =
-  let* bindings0 = betree_Node_lookup_mut_in_bindings key bindings in
-  let* b = betree_ListTupleU64T_head_has_key u64 bindings0 key in
+  let* (bindings1, lookup_mut_in_bindings_back) =
+    betree_Node_lookup_mut_in_bindings key bindings in
+  let* b = betree_ListTupleU64T_head_has_key u64 bindings1 key in
   if b
   then
-    let* hd = betree_List_pop_front (u64 & u64) bindings0 in
+    let* (hd, l) = betree_List_pop_front (u64 & u64) bindings1 in
     begin match new_msg with
     | Betree_Message_Insert v ->
-      let* bindings1 = betree_List_pop_front_back (u64 & u64) bindings0 in
-      let* bindings2 = betree_List_push_front (u64 & u64) bindings1 (key, v) in
-      betree_Node_lookup_mut_in_bindings_back key bindings bindings2
-    | Betree_Message_Delete ->
-      let* bindings1 = betree_List_pop_front_back (u64 & u64) bindings0 in
-      betree_Node_lookup_mut_in_bindings_back key bindings bindings1
+      let* l1 = betree_List_push_front (u64 & u64) l (key, v) in
+      lookup_mut_in_bindings_back l1
+    | Betree_Message_Delete -> lookup_mut_in_bindings_back l
     | Betree_Message_Upsert s ->
       let (_, i) = hd in
       let* v = betree_upsert_update (Some i) s in
-      let* bindings1 = betree_List_pop_front_back (u64 & u64) bindings0 in
-      let* bindings2 = betree_List_push_front (u64 & u64) bindings1 (key, v) in
-      betree_Node_lookup_mut_in_bindings_back key bindings bindings2
+      let* l1 = betree_List_push_front (u64 & u64) l (key, v) in
+      lookup_mut_in_bindings_back l1
     end
   else
     begin match new_msg with
     | Betree_Message_Insert v ->
-      let* bindings1 = betree_List_push_front (u64 & u64) bindings0 (key, v) in
-      betree_Node_lookup_mut_in_bindings_back key bindings bindings1
-    | Betree_Message_Delete ->
-      betree_Node_lookup_mut_in_bindings_back key bindings bindings0
+      let* l = betree_List_push_front (u64 & u64) bindings1 (key, v) in
+      lookup_mut_in_bindings_back l
+    | Betree_Message_Delete -> lookup_mut_in_bindings_back bindings1
     | Betree_Message_Upsert s ->
       let* v = betree_upsert_update None s in
-      let* bindings1 = betree_List_push_front (u64 & u64) bindings0 (key, v) in
-      betree_Node_lookup_mut_in_bindings_back key bindings bindings1
+      let* l = betree_List_push_front (u64 & u64) bindings1 (key, v) in
+      lookup_mut_in_bindings_back l
     end
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages_to_leaf]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages_to_leaf]:
     Source: 'src/betree.rs', lines 444:4-447:5 *)
 let rec betree_Node_apply_messages_to_leaf
   (bindings : betree_List_t (u64 & u64))
@@ -696,18 +517,19 @@ let rec betree_Node_apply_messages_to_leaf
   begin match new_msgs with
   | Betree_List_Cons new_msg new_msgs_tl ->
     let (i, m) = new_msg in
-    let* bindings0 = betree_Node_apply_to_leaf bindings i m in
-    betree_Node_apply_messages_to_leaf bindings0 new_msgs_tl
+    let* l = betree_Node_apply_to_leaf bindings i m in
+    betree_Node_apply_messages_to_leaf l new_msgs_tl
   | Betree_List_Nil -> Return bindings
   end
 
-(** [betree_main::betree::{betree_main::betree::Internal#4}::flush]: forward function
+(** [betree_main::betree::{betree_main::betree::Internal#4}::flush]:
     Source: 'src/betree.rs', lines 410:4-415:26 *)
 let rec betree_Internal_flush
   (self : betree_Internal_t) (params : betree_Params_t)
   (node_id_cnt : betree_NodeIdCounter_t)
   (content : betree_List_t (u64 & betree_Message_t)) (st : state) :
-  Tot (result (state & (betree_List_t (u64 & betree_Message_t))))
+  Tot (result (state & ((betree_List_t (u64 & betree_Message_t)) &
+    (betree_Internal_t & betree_NodeIdCounter_t))))
   (decreases (
     betree_Internal_flush_decreases self params node_id_cnt content st))
   =
@@ -718,290 +540,143 @@ let rec betree_Internal_flush
   let* len_left = betree_List_len (u64 & betree_Message_t) msgs_left in
   if len_left >= params.min_flush_size
   then
-    let* (st0, _) =
+    let* (st1, p1) =
       betree_Node_apply_messages self.left params node_id_cnt msgs_left st in
-    let* (_, node_id_cnt0) =
-      betree_Node_apply_messages_back self.left params node_id_cnt msgs_left st
-      in
+    let (n, node_id_cnt1) = p1 in
     let* len_right = betree_List_len (u64 & betree_Message_t) msgs_right in
     if len_right >= params.min_flush_size
     then
-      let* (st1, _) =
-        betree_Node_apply_messages self.right params node_id_cnt0 msgs_right
-          st0 in
-      let* _ =
-        betree_Node_apply_messages_back self.right params node_id_cnt0
-          msgs_right st0 in
-      Return (st1, Betree_List_Nil)
-    else Return (st0, msgs_right)
+      let* (st2, p2) =
+        betree_Node_apply_messages self.right params node_id_cnt1 msgs_right
+          st1 in
+      let (n1, node_id_cnt2) = p2 in
+      Return (st2, (Betree_List_Nil, ({ self with left = n; right = n1 },
+        node_id_cnt2)))
+    else Return (st1, (msgs_right, ({ self with left = n }, node_id_cnt1)))
   else
-    let* (st0, _) =
+    let* (st1, p1) =
       betree_Node_apply_messages self.right params node_id_cnt msgs_right st in
-    let* _ =
-      betree_Node_apply_messages_back self.right params node_id_cnt msgs_right
-        st in
-    Return (st0, msgs_left)
+    let (n, node_id_cnt1) = p1 in
+    Return (st1, (msgs_left, ({ self with right = n }, node_id_cnt1)))
 
-(** [betree_main::betree::{betree_main::betree::Internal#4}::flush]: backward function 0
-    Source: 'src/betree.rs', lines 410:4-415:26 *)
-and betree_Internal_flush_back
-  (self : betree_Internal_t) (params : betree_Params_t)
-  (node_id_cnt : betree_NodeIdCounter_t)
-  (content : betree_List_t (u64 & betree_Message_t)) (st : state) :
-  Tot (result (betree_Internal_t & betree_NodeIdCounter_t))
-  (decreases (
-    betree_Internal_flush_decreases self params node_id_cnt content st))
-  =
-  let* p =
-    betree_ListTupleU64T_partition_at_pivot betree_Message_t content self.pivot
-    in
-  let (msgs_left, msgs_right) = p in
-  let* len_left = betree_List_len (u64 & betree_Message_t) msgs_left in
-  if len_left >= params.min_flush_size
-  then
-    let* (st0, _) =
-      betree_Node_apply_messages self.left params node_id_cnt msgs_left st in
-    let* (n, node_id_cnt0) =
-      betree_Node_apply_messages_back self.left params node_id_cnt msgs_left st
-      in
-    let* len_right = betree_List_len (u64 & betree_Message_t) msgs_right in
-    if len_right >= params.min_flush_size
-    then
-      let* (n0, node_id_cnt1) =
-        betree_Node_apply_messages_back self.right params node_id_cnt0
-          msgs_right st0 in
-      Return ({ self with left = n; right = n0 }, node_id_cnt1)
-    else Return ({ self with left = n }, node_id_cnt0)
-  else
-    let* (n, node_id_cnt0) =
-      betree_Node_apply_messages_back self.right params node_id_cnt msgs_right
-        st in
-    Return ({ self with right = n }, node_id_cnt0)
-
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages]: forward function
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages]:
     Source: 'src/betree.rs', lines 588:4-593:5 *)
 and betree_Node_apply_messages
   (self : betree_Node_t) (params : betree_Params_t)
   (node_id_cnt : betree_NodeIdCounter_t)
   (msgs : betree_List_t (u64 & betree_Message_t)) (st : state) :
-  Tot (result (state & unit))
-  (decreases (
-    betree_Node_apply_messages_decreases self params node_id_cnt msgs st))
-  =
-  begin match self with
-  | Betree_Node_Internal node ->
-    let* (st0, content) = betree_load_internal_node node.id st in
-    let* content0 = betree_Node_apply_messages_to_internal content msgs in
-    let* num_msgs = betree_List_len (u64 & betree_Message_t) content0 in
-    if num_msgs >= params.min_flush_size
-    then
-      let* (st1, content1) =
-        betree_Internal_flush node params node_id_cnt content0 st0 in
-      let* (node0, _) =
-        betree_Internal_flush_back node params node_id_cnt content0 st0 in
-      let* (st2, _) = betree_store_internal_node node0.id content1 st1 in
-      Return (st2, ())
-    else
-      let* (st1, _) = betree_store_internal_node node.id content0 st0 in
-      Return (st1, ())
-  | Betree_Node_Leaf node ->
-    let* (st0, content) = betree_load_leaf_node node.id st in
-    let* content0 = betree_Node_apply_messages_to_leaf content msgs in
-    let* len = betree_List_len (u64 & u64) content0 in
-    let* i = u64_mul 2 params.split_size in
-    if len >= i
-    then
-      let* (st1, _) = betree_Leaf_split node content0 params node_id_cnt st0 in
-      let* (st2, _) = betree_store_leaf_node node.id Betree_List_Nil st1 in
-      Return (st2, ())
-    else
-      let* (st1, _) = betree_store_leaf_node node.id content0 st0 in
-      Return (st1, ())
-  end
-
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages]: backward function 0
-    Source: 'src/betree.rs', lines 588:4-593:5 *)
-and betree_Node_apply_messages_back
-  (self : betree_Node_t) (params : betree_Params_t)
-  (node_id_cnt : betree_NodeIdCounter_t)
-  (msgs : betree_List_t (u64 & betree_Message_t)) (st : state) :
-  Tot (result (betree_Node_t & betree_NodeIdCounter_t))
+  Tot (result (state & (betree_Node_t & betree_NodeIdCounter_t)))
   (decreases (
     betree_Node_apply_messages_decreases self params node_id_cnt msgs st))
   =
   begin match self with
   | Betree_Node_Internal node ->
-    let* (st0, content) = betree_load_internal_node node.id st in
-    let* content0 = betree_Node_apply_messages_to_internal content msgs in
-    let* num_msgs = betree_List_len (u64 & betree_Message_t) content0 in
+    let* (st1, content) = betree_load_internal_node node.id st in
+    let* l = betree_Node_apply_messages_to_internal content msgs in
+    let* num_msgs = betree_List_len (u64 & betree_Message_t) l in
     if num_msgs >= params.min_flush_size
     then
-      let* (st1, content1) =
-        betree_Internal_flush node params node_id_cnt content0 st0 in
-      let* (node0, node_id_cnt0) =
-        betree_Internal_flush_back node params node_id_cnt content0 st0 in
-      let* _ = betree_store_internal_node node0.id content1 st1 in
-      Return (Betree_Node_Internal node0, node_id_cnt0)
+      let* (st2, (content1, p)) =
+        betree_Internal_flush node params node_id_cnt l st1 in
+      let (node1, node_id_cnt1) = p in
+      let* (st3, _) = betree_store_internal_node node1.id content1 st2 in
+      Return (st3, (Betree_Node_Internal node1, node_id_cnt1))
     else
-      let* _ = betree_store_internal_node node.id content0 st0 in
-      Return (Betree_Node_Internal node, node_id_cnt)
+      let* (st2, _) = betree_store_internal_node node.id l st1 in
+      Return (st2, (Betree_Node_Internal node, node_id_cnt))
   | Betree_Node_Leaf node ->
-    let* (st0, content) = betree_load_leaf_node node.id st in
-    let* content0 = betree_Node_apply_messages_to_leaf content msgs in
-    let* len = betree_List_len (u64 & u64) content0 in
+    let* (st1, content) = betree_load_leaf_node node.id st in
+    let* l = betree_Node_apply_messages_to_leaf content msgs in
+    let* len = betree_List_len (u64 & u64) l in
     let* i = u64_mul 2 params.split_size in
     if len >= i
     then
-      let* (st1, new_node) =
-        betree_Leaf_split node content0 params node_id_cnt st0 in
-      let* _ = betree_store_leaf_node node.id Betree_List_Nil st1 in
-      let* node_id_cnt0 =
-        betree_Leaf_split_back node content0 params node_id_cnt st0 in
-      Return (Betree_Node_Internal new_node, node_id_cnt0)
+      let* (st2, (new_node, nic)) =
+        betree_Leaf_split node l params node_id_cnt st1 in
+      let* (st3, _) = betree_store_leaf_node node.id Betree_List_Nil st2 in
+      Return (st3, (Betree_Node_Internal new_node, nic))
     else
-      let* _ = betree_store_leaf_node node.id content0 st0 in
-      Return (Betree_Node_Leaf { node with size = len }, node_id_cnt)
+      let* (st2, _) = betree_store_leaf_node node.id l st1 in
+      Return (st2, (Betree_Node_Leaf { node with size = len }, node_id_cnt))
   end
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply]: forward function
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply]:
     Source: 'src/betree.rs', lines 576:4-582:5 *)
 let betree_Node_apply
   (self : betree_Node_t) (params : betree_Params_t)
   (node_id_cnt : betree_NodeIdCounter_t) (key : u64)
   (new_msg : betree_Message_t) (st : state) :
-  result (state & unit)
+  result (state & (betree_Node_t & betree_NodeIdCounter_t))
   =
   let l = Betree_List_Nil in
-  let* (st0, _) =
+  let* (st1, p) =
     betree_Node_apply_messages self params node_id_cnt (Betree_List_Cons (key,
       new_msg) l) st in
-  let* _ =
-    betree_Node_apply_messages_back self params node_id_cnt (Betree_List_Cons
-      (key, new_msg) l) st in
-  Return (st0, ())
+  let (self1, node_id_cnt1) = p in
+  Return (st1, (self1, node_id_cnt1))
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply]: backward function 0
-    Source: 'src/betree.rs', lines 576:4-582:5 *)
-let betree_Node_apply_back
-  (self : betree_Node_t) (params : betree_Params_t)
-  (node_id_cnt : betree_NodeIdCounter_t) (key : u64)
-  (new_msg : betree_Message_t) (st : state) :
-  result (betree_Node_t & betree_NodeIdCounter_t)
-  =
-  let l = Betree_List_Nil in
-  betree_Node_apply_messages_back self params node_id_cnt (Betree_List_Cons
-    (key, new_msg) l) st
-
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::new]: forward function
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::new]:
     Source: 'src/betree.rs', lines 849:4-849:60 *)
 let betree_BeTree_new
   (min_flush_size : u64) (split_size : u64) (st : state) :
   result (state & betree_BeTree_t)
   =
   let* node_id_cnt = betree_NodeIdCounter_new in
-  let* id = betree_NodeIdCounter_fresh_id node_id_cnt in
-  let* (st0, _) = betree_store_leaf_node id Betree_List_Nil st in
-  let* node_id_cnt0 = betree_NodeIdCounter_fresh_id_back node_id_cnt in
-  Return (st0,
+  let* (id, nic) = betree_NodeIdCounter_fresh_id node_id_cnt in
+  let* (st1, _) = betree_store_leaf_node id Betree_List_Nil st in
+  Return (st1,
     {
       params = { min_flush_size = min_flush_size; split_size = split_size };
-      node_id_cnt = node_id_cnt0;
+      node_id_cnt = nic;
       root = (Betree_Node_Leaf { id = id; size = 0 })
     })
 
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::apply]: forward function
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::apply]:
     Source: 'src/betree.rs', lines 868:4-868:47 *)
 let betree_BeTree_apply
   (self : betree_BeTree_t) (key : u64) (msg : betree_Message_t) (st : state) :
-  result (state & unit)
+  result (state & betree_BeTree_t)
   =
-  let* (st0, _) =
+  let* (st1, p) =
     betree_Node_apply self.root self.params self.node_id_cnt key msg st in
-  let* _ =
-    betree_Node_apply_back self.root self.params self.node_id_cnt key msg st in
-  Return (st0, ())
+  let (n, nic) = p in
+  Return (st1, { self with node_id_cnt = nic; root = n })
 
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::apply]: backward function 0
-    Source: 'src/betree.rs', lines 868:4-868:47 *)
-let betree_BeTree_apply_back
-  (self : betree_BeTree_t) (key : u64) (msg : betree_Message_t) (st : state) :
-  result betree_BeTree_t
-  =
-  let* (n, nic) =
-    betree_Node_apply_back self.root self.params self.node_id_cnt key msg st in
-  Return { self with node_id_cnt = nic; root = n }
-
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::insert]: forward function
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::insert]:
     Source: 'src/betree.rs', lines 874:4-874:52 *)
 let betree_BeTree_insert
   (self : betree_BeTree_t) (key : u64) (value : u64) (st : state) :
-  result (state & unit)
-  =
-  let* (st0, _) = betree_BeTree_apply self key (Betree_Message_Insert value) st
-    in
-  let* _ = betree_BeTree_apply_back self key (Betree_Message_Insert value) st
-    in
-  Return (st0, ())
-
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::insert]: backward function 0
-    Source: 'src/betree.rs', lines 874:4-874:52 *)
-let betree_BeTree_insert_back
-  (self : betree_BeTree_t) (key : u64) (value : u64) (st : state) :
-  result betree_BeTree_t
+  result (state & betree_BeTree_t)
   =
-  betree_BeTree_apply_back self key (Betree_Message_Insert value) st
+  betree_BeTree_apply self key (Betree_Message_Insert value) st
 
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::delete]: forward function
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::delete]:
     Source: 'src/betree.rs', lines 880:4-880:38 *)
 let betree_BeTree_delete
-  (self : betree_BeTree_t) (key : u64) (st : state) : result (state & unit) =
-  let* (st0, _) = betree_BeTree_apply self key Betree_Message_Delete st in
-  let* _ = betree_BeTree_apply_back self key Betree_Message_Delete st in
-  Return (st0, ())
-
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::delete]: backward function 0
-    Source: 'src/betree.rs', lines 880:4-880:38 *)
-let betree_BeTree_delete_back
-  (self : betree_BeTree_t) (key : u64) (st : state) : result betree_BeTree_t =
-  betree_BeTree_apply_back self key Betree_Message_Delete st
-
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::upsert]: forward function
-    Source: 'src/betree.rs', lines 886:4-886:59 *)
-let betree_BeTree_upsert
-  (self : betree_BeTree_t) (key : u64) (upd : betree_UpsertFunState_t)
-  (st : state) :
-  result (state & unit)
+  (self : betree_BeTree_t) (key : u64) (st : state) :
+  result (state & betree_BeTree_t)
   =
-  let* (st0, _) = betree_BeTree_apply self key (Betree_Message_Upsert upd) st
-    in
-  let* _ = betree_BeTree_apply_back self key (Betree_Message_Upsert upd) st in
-  Return (st0, ())
+  betree_BeTree_apply self key Betree_Message_Delete st
 
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::upsert]: backward function 0
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::upsert]:
     Source: 'src/betree.rs', lines 886:4-886:59 *)
-let betree_BeTree_upsert_back
+let betree_BeTree_upsert
   (self : betree_BeTree_t) (key : u64) (upd : betree_UpsertFunState_t)
   (st : state) :
-  result betree_BeTree_t
+  result (state & betree_BeTree_t)
   =
-  betree_BeTree_apply_back self key (Betree_Message_Upsert upd) st
+  betree_BeTree_apply self key (Betree_Message_Upsert upd) st
 
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::lookup]: forward function
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::lookup]:
     Source: 'src/betree.rs', lines 895:4-895:62 *)
 let betree_BeTree_lookup
   (self : betree_BeTree_t) (key : u64) (st : state) :
-  result (state & (option u64))
+  result (state & ((option u64) & betree_BeTree_t))
   =
-  betree_Node_lookup self.root key st
-
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::lookup]: backward function 0
-    Source: 'src/betree.rs', lines 895:4-895:62 *)
-let betree_BeTree_lookup_back
-  (self : betree_BeTree_t) (key : u64) (st : state) : result betree_BeTree_t =
-  let* n = betree_Node_lookup_back self.root key st in
-  Return { self with root = n }
+  let* (st1, (o, n)) = betree_Node_lookup self.root key st in
+  Return (st1, (o, { self with root = n }))
 
-(** [betree_main::main]: forward function
+(** [betree_main::main]:
     Source: 'src/betree_main.rs', lines 5:0-5:9 *)
 let main : result unit =
   Return ()
diff --git a/tests/fstar/betree/BetreeMain.FunsExternal.fsti b/tests/fstar/betree/BetreeMain.FunsExternal.fsti
index cd2f956f..de9b96fd 100644
--- a/tests/fstar/betree/BetreeMain.FunsExternal.fsti
+++ b/tests/fstar/betree/BetreeMain.FunsExternal.fsti
@@ -6,29 +6,29 @@ include BetreeMain.Types
 
 #set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
 
-(** [betree_main::betree_utils::load_internal_node]: forward function
+(** [betree_main::betree_utils::load_internal_node]:
     Source: 'src/betree_utils.rs', lines 98:0-98:63 *)
 val betree_utils_load_internal_node
   : u64 -> state -> result (state & (betree_List_t (u64 & betree_Message_t)))
 
-(** [betree_main::betree_utils::store_internal_node]: forward function
+(** [betree_main::betree_utils::store_internal_node]:
     Source: 'src/betree_utils.rs', lines 115:0-115:71 *)
 val betree_utils_store_internal_node
   :
   u64 -> betree_List_t (u64 & betree_Message_t) -> state -> result (state &
     unit)
 
-(** [betree_main::betree_utils::load_leaf_node]: forward function
+(** [betree_main::betree_utils::load_leaf_node]:
     Source: 'src/betree_utils.rs', lines 132:0-132:55 *)
 val betree_utils_load_leaf_node
   : u64 -> state -> result (state & (betree_List_t (u64 & u64)))
 
-(** [betree_main::betree_utils::store_leaf_node]: forward function
+(** [betree_main::betree_utils::store_leaf_node]:
     Source: 'src/betree_utils.rs', lines 145:0-145:63 *)
 val betree_utils_store_leaf_node
   : u64 -> betree_List_t (u64 & u64) -> state -> result (state & unit)
 
-(** [core::option::{core::option::Option<T>}::unwrap]: forward function
+(** [core::option::{core::option::Option<T>}::unwrap]:
     Source: '/rustc/d59363ad0b6391b7fc5bbb02c9ccf9300eef3753/library/core/src/option.rs', lines 932:4-932:34 *)
 val core_option_Option_unwrap
   (t : Type0) : option t -> state -> result (state & t)
diff --git a/tests/fstar/betree/Primitives.fst b/tests/fstar/betree/Primitives.fst
index a3ffbde4..fca80829 100644
--- a/tests/fstar/betree/Primitives.fst
+++ b/tests/fstar/betree/Primitives.fst
@@ -55,8 +55,7 @@ type string = string
 let is_zero (n: nat) : bool = n = 0
 let decrease (n: nat{n > 0}) : nat = n - 1
 
-let core_mem_replace (a : Type0) (x : a) (y : a) : a = x
-let core_mem_replace_back (a : Type0) (x : a) (y : a) : a = y
+let core_mem_replace (a : Type0) (x : a) (y : a) : a & a = (x, x)
 
 // We don't really use raw pointers for now
 type mut_raw_ptr (t : Type0) = { v : t }
@@ -477,8 +476,7 @@ noeq type core_ops_index_Index (self idx : Type0) = {
 // Trait declaration: [core::ops::index::IndexMut]
 noeq type core_ops_index_IndexMut (self idx : Type0) = {
   indexInst : core_ops_index_Index self idx;
-  index_mut : self → idx → result indexInst.output;
-  index_mut_back : self → idx → indexInst.output → result self;
+  index_mut : self → idx → result (indexInst.output & (indexInst.output → result self));
 }
 
 // Trait declaration [core::ops::deref::Deref]
@@ -490,8 +488,7 @@ noeq type core_ops_deref_Deref (self : Type0) = {
 // Trait declaration [core::ops::deref::DerefMut]
 noeq type core_ops_deref_DerefMut (self : Type0) = {
   derefInst : core_ops_deref_Deref self;
-  deref_mut : self → result derefInst.target;
-  deref_mut_back : self → derefInst.target → result self;
+  deref_mut : self → result (derefInst.target & (derefInst.target → result self));
 }
 
 type core_ops_range_Range (a : Type0) = {
@@ -502,8 +499,8 @@ type core_ops_range_Range (a : Type0) = {
 (*** [alloc] *)
 
 let alloc_boxed_Box_deref (t : Type0) (x : t) : result t = Return x
-let alloc_boxed_Box_deref_mut (t : Type0) (x : t) : result t = Return x
-let alloc_boxed_Box_deref_mut_back (t : Type) (_ : t) (x : t) : result t = Return x
+let alloc_boxed_Box_deref_mut (t : Type0) (x : t) : result (t & (t -> result t)) =
+  Return (x, (fun x -> Return x))
 
 // Trait instance
 let alloc_boxed_Box_coreopsDerefInst (self : Type0) : core_ops_deref_Deref self = {
@@ -515,7 +512,6 @@ let alloc_boxed_Box_coreopsDerefInst (self : Type0) : core_ops_deref_Deref self
 let alloc_boxed_Box_coreopsDerefMutInst (self : Type0) : core_ops_deref_DerefMut self = {
   derefInst = alloc_boxed_Box_coreopsDerefInst self;
   deref_mut = alloc_boxed_Box_deref_mut self;
-  deref_mut_back = alloc_boxed_Box_deref_mut_back self;
 }
 
 (*** Array *)
@@ -535,10 +531,18 @@ let array_index_usize (a : Type0) (n : usize) (x : array a n) (i : usize) : resu
   if i < length x then Return (index x i)
   else Fail Failure
 
-let array_update_usize (a : Type0) (n : usize) (x : array a n) (i : usize) (nx : a) : result (array a n) =
+let array_update_usize (a : Type0) (n : usize) (x : array a n) (i : usize) (nx : a) :
+  result (array a n) =
   if i < length x then Return (list_update x i nx)
   else Fail Failure
 
+let array_index_mut_usize (a : Type0) (n : usize) (x : array a n) (i : usize) :
+  result (a & (a -> result (array a n))) =
+  match array_index_usize a n x i with
+  | Fail e -> Fail e
+  | Return v ->
+    Return (v, array_update_usize a n x i)
+
 (*** Slice *)
 type slice (a : Type0) = s:list a{length s <= usize_max}
 
@@ -552,6 +556,13 @@ let slice_update_usize (a : Type0) (x : slice a) (i : usize) (nx : a) : result (
   if i < length x then Return (list_update x i nx)
   else Fail Failure
 
+let slice_index_mut_usize (a : Type0) (s : slice a) (i : usize) :
+  result (a & (a -> result (slice a))) =
+  match slice_index_usize a s i with
+  | Fail e -> Fail e
+  | Return x ->
+    Return (x, slice_update_usize a s i)
+
 (*** Subslices *)
 
 let array_to_slice (a : Type0) (n : usize) (x : array a n) : result (slice a) = Return x
@@ -559,6 +570,10 @@ let array_from_slice (a : Type0) (n : usize) (x : array a n) (s : slice a) : res
   if length s = n then Return s
   else Fail Failure
 
+let array_to_slice_mut (a : Type0) (n : usize) (x : array a n) :
+  result (slice a & (slice a -> result (array a n))) =
+  Return (x, array_from_slice a n x)
+
 // TODO: finish the definitions below (there lacks [List.drop] and [List.take] in the standard library *)
 let array_subslice (a : Type0) (n : usize) (x : array a n) (r : core_ops_range_Range usize) : result (slice a) =
   admit()
@@ -588,8 +603,13 @@ let alloc_vec_Vec_index_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) : r
 let alloc_vec_Vec_update_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
   if i < length v then Return (list_update v i x) else Fail Failure
 
-// The **forward** function shouldn't be used
-let alloc_vec_Vec_push_fwd (a  : Type0) (v : alloc_vec_Vec a) (x : a) : unit = ()
+let alloc_vec_Vec_index_mut_usize (#a : Type0) (v: alloc_vec_Vec a) (i: usize) :
+  result (a & (a → result (alloc_vec_Vec a))) =
+  match alloc_vec_Vec_index_usize v i with
+  | Return x ->
+    Return (x, alloc_vec_Vec_update_usize v i)
+  | Fail e -> Fail e
+
 let alloc_vec_Vec_push (a  : Type0) (v : alloc_vec_Vec a) (x : a) :
   Pure (result (alloc_vec_Vec a))
   (requires True)
@@ -605,9 +625,6 @@ let alloc_vec_Vec_push (a  : Type0) (v : alloc_vec_Vec a) (x : a) :
     end
   else Fail Failure
 
-// The **forward** function shouldn't be used
-let alloc_vec_Vec_insert_fwd (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result unit =
-  if i < length v then Return () else Fail Failure
 let alloc_vec_Vec_insert (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
   if i < length v then Return (list_update v i x) else Fail Failure
 
@@ -619,13 +636,11 @@ noeq type core_slice_index_SliceIndex (self t : Type0) = {
   sealedInst : core_slice_index_private_slice_index_Sealed self;
   output : Type0;
   get : self → t → result (option output);
-  get_mut : self → t → result (option output);
-  get_mut_back : self → t → option output → result t;
+  get_mut : self → t → result (option output & (option output -> result t));
   get_unchecked : self → const_raw_ptr t → result (const_raw_ptr output);
   get_unchecked_mut : self → mut_raw_ptr t → result (mut_raw_ptr output);
   index : self → t → result output;
-  index_mut : self → t → result output;
-  index_mut_back : self → t → output → result t;
+  index_mut : self → t → result (output & (output -> result t));
 }
 
 // [core::slice::index::[T]::index]: forward function
@@ -643,14 +658,8 @@ let core_slice_index_RangeUsize_get (t : Type0) (i : core_ops_range_Range usize)
   admit () // TODO
 
 // [core::slice::index::Range::get_mut]: forward function
-let core_slice_index_RangeUsize_get_mut
-  (t : Type0) : core_ops_range_Range usize → slice t → result (option (slice t)) =
-  admit () // TODO
-
-// [core::slice::index::Range::get_mut]: backward function 0
-let core_slice_index_RangeUsize_get_mut_back
-  (t : Type0) :
-  core_ops_range_Range usize → slice t → option (slice t) → result (slice t) =
+let core_slice_index_RangeUsize_get_mut (t : Type0) :
+  core_ops_range_Range usize → slice t → result (option (slice t) & (option (slice t) -> result (slice t))) =
   admit () // TODO
 
 // [core::slice::index::Range::get_unchecked]: forward function
@@ -675,27 +684,16 @@ let core_slice_index_RangeUsize_index
   admit () // TODO
 
 // [core::slice::index::Range::index_mut]: forward function
-let core_slice_index_RangeUsize_index_mut
-  (t : Type0) : core_ops_range_Range usize → slice t → result (slice t) =
-  admit () // TODO
-
-// [core::slice::index::Range::index_mut]: backward function 0
-let core_slice_index_RangeUsize_index_mut_back
-  (t : Type0) : core_ops_range_Range usize → slice t → slice t → result (slice t) =
+let core_slice_index_RangeUsize_index_mut (t : Type0) :
+  core_ops_range_Range usize → slice t → result (slice t & (slice t -> result (slice t))) =
   admit () // TODO
 
 // [core::slice::index::[T]::index_mut]: forward function
 let core_slice_index_Slice_index_mut
   (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
-  slice t → idx → result inst.output =
+  slice t → idx → result (inst.output & (inst.output -> result (slice t))) =
   admit () // 
 
-// [core::slice::index::[T]::index_mut]: backward function 0
-let core_slice_index_Slice_index_mut_back
-  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
-  slice t → idx → inst.output → result (slice t) =
-  admit () // TODO
-
 // [core::array::[T; N]::index]: forward function
 let core_array_Array_index
   (t idx : Type0) (n : usize) (inst : core_ops_index_Index (slice t) idx)
@@ -705,13 +703,8 @@ let core_array_Array_index
 // [core::array::[T; N]::index_mut]: forward function
 let core_array_Array_index_mut
   (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
-  (a : array t n) (i : idx) : result inst.indexInst.output =
-  admit () // TODO
-
-// [core::array::[T; N]::index_mut]: backward function 0
-let core_array_Array_index_mut_back
-  (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
-  (a : array t n) (i : idx) (x : inst.indexInst.output) : result (array t n) =
+  (a : array t n) (i : idx) :
+  result (inst.indexInst.output & (inst.indexInst.output -> result (array t n))) =
   admit () // TODO
 
 // Trait implementation: [core::slice::index::private_slice_index::Range]
@@ -725,12 +718,10 @@ let core_slice_index_SliceIndexRangeUsizeSliceTInst (t : Type0) :
   output = slice t;
   get = core_slice_index_RangeUsize_get t;
   get_mut = core_slice_index_RangeUsize_get_mut t;
-  get_mut_back = core_slice_index_RangeUsize_get_mut_back t;
   get_unchecked = core_slice_index_RangeUsize_get_unchecked t;
   get_unchecked_mut = core_slice_index_RangeUsize_get_unchecked_mut t;
   index = core_slice_index_RangeUsize_index t;
   index_mut = core_slice_index_RangeUsize_index_mut t;
-  index_mut_back = core_slice_index_RangeUsize_index_mut_back t;
 }
 
 // Trait implementation: [core::slice::index::[T]]
@@ -747,7 +738,6 @@ let core_ops_index_IndexMutSliceTIInst (t idx : Type0)
   core_ops_index_IndexMut (slice t) idx = {
   indexInst = core_ops_index_IndexSliceTIInst t idx inst;
   index_mut = core_slice_index_Slice_index_mut t idx inst;
-  index_mut_back = core_slice_index_Slice_index_mut_back t idx inst;
 }
 
 // Trait implementation: [core::array::[T; N]]
@@ -764,7 +754,6 @@ let core_ops_index_IndexMutArrayIInst (t idx : Type0) (n : usize)
   core_ops_index_IndexMut (array t n) idx = {
   indexInst = core_ops_index_IndexArrayInst t idx n inst.indexInst;
   index_mut = core_array_Array_index_mut t idx n inst;
-  index_mut_back = core_array_Array_index_mut_back t idx n inst;
 }
 
 // [core::slice::index::usize::get]: forward function
@@ -773,13 +762,8 @@ let core_slice_index_usize_get
   admit () // TODO
 
 // [core::slice::index::usize::get_mut]: forward function
-let core_slice_index_usize_get_mut
-  (t : Type0) : usize → slice t → result (option t) =
-  admit () // TODO
-
-// [core::slice::index::usize::get_mut]: backward function 0
-let core_slice_index_usize_get_mut_back
-  (t : Type0) : usize → slice t → option t → result (slice t) =
+let core_slice_index_usize_get_mut (t : Type0) :
+  usize → slice t → result (option t & (option t -> result (slice t))) =
   admit () // TODO
 
 // [core::slice::index::usize::get_unchecked]: forward function
@@ -797,12 +781,8 @@ let core_slice_index_usize_index (t : Type0) : usize → slice t → result t =
   admit () // TODO
 
 // [core::slice::index::usize::index_mut]: forward function
-let core_slice_index_usize_index_mut (t : Type0) : usize → slice t → result t =
-  admit () // TODO
-
-// [core::slice::index::usize::index_mut]: backward function 0
-let core_slice_index_usize_index_mut_back
-  (t : Type0) : usize → slice t → t → result (slice t) =
+let core_slice_index_usize_index_mut (t : Type0) :
+  usize → slice t → result (t & (t -> result (slice t))) =
   admit () // TODO
 
 // Trait implementation: [core::slice::index::private_slice_index::usize]
@@ -816,12 +796,10 @@ let core_slice_index_SliceIndexUsizeSliceTInst (t : Type0) :
   output = t;
   get = core_slice_index_usize_get t;
   get_mut = core_slice_index_usize_get_mut t;
-  get_mut_back = core_slice_index_usize_get_mut_back t;
   get_unchecked = core_slice_index_usize_get_unchecked t;
   get_unchecked_mut = core_slice_index_usize_get_unchecked_mut t;
   index = core_slice_index_usize_index t;
   index_mut = core_slice_index_usize_index_mut t;
-  index_mut_back = core_slice_index_usize_index_mut_back t;
 }
 
 // [alloc::vec::Vec::index]: forward function
@@ -831,13 +809,8 @@ let alloc_vec_Vec_index (t idx : Type0) (inst : core_slice_index_SliceIndex idx
 
 // [alloc::vec::Vec::index_mut]: forward function
 let alloc_vec_Vec_index_mut (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
-  (self : alloc_vec_Vec t) (i : idx) : result inst.output =
-  admit () // TODO
-
-// [alloc::vec::Vec::index_mut]: backward function 0
-let alloc_vec_Vec_index_mut_back
-  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
-  (self : alloc_vec_Vec t) (i : idx) (x : inst.output) : result (alloc_vec_Vec t) =
+  (self : alloc_vec_Vec t) (i : idx) :
+  result (inst.output & (inst.output -> result (alloc_vec_Vec t))) =
   admit () // TODO
 
 // Trait implementation: [alloc::vec::Vec]
@@ -854,7 +827,6 @@ let alloc_vec_Vec_coreopsindexIndexMutInst (t idx : Type0)
   core_ops_index_IndexMut (alloc_vec_Vec t) idx = {
   indexInst = alloc_vec_Vec_coreopsindexIndexInst t idx inst;
   index_mut = alloc_vec_Vec_index_mut t idx inst;
-  index_mut_back = alloc_vec_Vec_index_mut_back t idx inst;
 }
 
 (*** Theorems *)
@@ -870,15 +842,7 @@ let alloc_vec_Vec_index_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
 let alloc_vec_Vec_index_mut_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
   Lemma (
     alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i ==
-      alloc_vec_Vec_index_usize v i)
+      alloc_vec_Vec_index_mut_usize v i)
   [SMTPat (alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i)]
   =
   admit()
-
-let alloc_vec_Vec_index_mut_back_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) :
-  Lemma (
-    alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x ==
-      alloc_vec_Vec_update_usize v i x)
-  [SMTPat (alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x)]
-  =
-  admit()
diff --git a/tests/fstar/betree_back_stateful/BetreeMain.Funs.fst b/tests/fstar/betree_back_stateful/BetreeMain.Funs.fst
index 6c3c2161..a3065f3d 100644
--- a/tests/fstar/betree_back_stateful/BetreeMain.Funs.fst
+++ b/tests/fstar/betree_back_stateful/BetreeMain.Funs.fst
@@ -8,7 +8,7 @@ include BetreeMain.Clauses
 
 #set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
 
-(** [betree_main::betree::load_internal_node]: forward function
+(** [betree_main::betree::load_internal_node]:
     Source: 'src/betree.rs', lines 36:0-36:52 *)
 let betree_load_internal_node
   (id : u64) (st : state) :
@@ -16,58 +16,48 @@ let betree_load_internal_node
   =
   betree_utils_load_internal_node id st
 
-(** [betree_main::betree::store_internal_node]: forward function
+(** [betree_main::betree::store_internal_node]:
     Source: 'src/betree.rs', lines 41:0-41:60 *)
 let betree_store_internal_node
   (id : u64) (content : betree_List_t (u64 & betree_Message_t)) (st : state) :
   result (state & unit)
   =
-  let* (st0, _) = betree_utils_store_internal_node id content st in
-  Return (st0, ())
+  let* (st1, _) = betree_utils_store_internal_node id content st in
+  Return (st1, ())
 
-(** [betree_main::betree::load_leaf_node]: forward function
+(** [betree_main::betree::load_leaf_node]:
     Source: 'src/betree.rs', lines 46:0-46:44 *)
 let betree_load_leaf_node
   (id : u64) (st : state) : result (state & (betree_List_t (u64 & u64))) =
   betree_utils_load_leaf_node id st
 
-(** [betree_main::betree::store_leaf_node]: forward function
+(** [betree_main::betree::store_leaf_node]:
     Source: 'src/betree.rs', lines 51:0-51:52 *)
 let betree_store_leaf_node
   (id : u64) (content : betree_List_t (u64 & u64)) (st : state) :
   result (state & unit)
   =
-  let* (st0, _) = betree_utils_store_leaf_node id content st in
-  Return (st0, ())
-
-(** [betree_main::betree::fresh_node_id]: forward function
-    Source: 'src/betree.rs', lines 55:0-55:48 *)
-let betree_fresh_node_id (counter : u64) : result u64 =
-  let* _ = u64_add counter 1 in Return counter
+  let* (st1, _) = betree_utils_store_leaf_node id content st in
+  Return (st1, ())
 
-(** [betree_main::betree::fresh_node_id]: backward function 0
+(** [betree_main::betree::fresh_node_id]:
     Source: 'src/betree.rs', lines 55:0-55:48 *)
-let betree_fresh_node_id_back (counter : u64) : result u64 =
-  u64_add counter 1
+let betree_fresh_node_id (counter : u64) : result (u64 & u64) =
+  let* counter1 = u64_add counter 1 in Return (counter, counter1)
 
-(** [betree_main::betree::{betree_main::betree::NodeIdCounter}::new]: forward function
+(** [betree_main::betree::{betree_main::betree::NodeIdCounter}::new]:
     Source: 'src/betree.rs', lines 206:4-206:20 *)
 let betree_NodeIdCounter_new : result betree_NodeIdCounter_t =
   Return { next_node_id = 0 }
 
-(** [betree_main::betree::{betree_main::betree::NodeIdCounter}::fresh_id]: forward function
+(** [betree_main::betree::{betree_main::betree::NodeIdCounter}::fresh_id]:
     Source: 'src/betree.rs', lines 210:4-210:36 *)
 let betree_NodeIdCounter_fresh_id
-  (self : betree_NodeIdCounter_t) : result u64 =
-  let* _ = u64_add self.next_node_id 1 in Return self.next_node_id
+  (self : betree_NodeIdCounter_t) : result (u64 & betree_NodeIdCounter_t) =
+  let* i = u64_add self.next_node_id 1 in
+  Return (self.next_node_id, { next_node_id = i })
 
-(** [betree_main::betree::{betree_main::betree::NodeIdCounter}::fresh_id]: backward function 0
-    Source: 'src/betree.rs', lines 210:4-210:36 *)
-let betree_NodeIdCounter_fresh_id_back
-  (self : betree_NodeIdCounter_t) : result betree_NodeIdCounter_t =
-  let* i = u64_add self.next_node_id 1 in Return { next_node_id = i }
-
-(** [betree_main::betree::upsert_update]: forward function
+(** [betree_main::betree::upsert_update]:
     Source: 'src/betree.rs', lines 234:0-234:70 *)
 let betree_upsert_update
   (prev : option u64) (st : betree_UpsertFunState_t) : result u64 =
@@ -75,30 +65,30 @@ let betree_upsert_update
   | None ->
     begin match st with
     | Betree_UpsertFunState_Add v -> Return v
-    | Betree_UpsertFunState_Sub i -> Return 0
+    | Betree_UpsertFunState_Sub _ -> Return 0
     end
-  | Some prev0 ->
+  | Some prev1 ->
     begin match st with
     | Betree_UpsertFunState_Add v ->
-      let* margin = u64_sub core_u64_max prev0 in
-      if margin >= v then u64_add prev0 v else Return core_u64_max
+      let* margin = u64_sub core_u64_max prev1 in
+      if margin >= v then u64_add prev1 v else Return core_u64_max
     | Betree_UpsertFunState_Sub v ->
-      if prev0 >= v then u64_sub prev0 v else Return 0
+      if prev1 >= v then u64_sub prev1 v else Return 0
     end
   end
 
-(** [betree_main::betree::{betree_main::betree::List<T>#1}::len]: forward function
+(** [betree_main::betree::{betree_main::betree::List<T>#1}::len]:
     Source: 'src/betree.rs', lines 276:4-276:24 *)
 let rec betree_List_len
   (t : Type0) (self : betree_List_t t) :
   Tot (result u64) (decreases (betree_List_len_decreases t self))
   =
   begin match self with
-  | Betree_List_Cons x tl -> let* i = betree_List_len t tl in u64_add 1 i
+  | Betree_List_Cons _ tl -> let* i = betree_List_len t tl in u64_add 1 i
   | Betree_List_Nil -> Return 0
   end
 
-(** [betree_main::betree::{betree_main::betree::List<T>#1}::split_at]: forward function
+(** [betree_main::betree::{betree_main::betree::List<T>#1}::split_at]:
     Source: 'src/betree.rs', lines 284:4-284:51 *)
 let rec betree_List_split_at
   (t : Type0) (self : betree_List_t t) (n : u64) :
@@ -118,52 +108,42 @@ let rec betree_List_split_at
     | Betree_List_Nil -> Fail Failure
     end
 
-(** [betree_main::betree::{betree_main::betree::List<T>#1}::push_front]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [betree_main::betree::{betree_main::betree::List<T>#1}::push_front]:
     Source: 'src/betree.rs', lines 299:4-299:34 *)
 let betree_List_push_front
   (t : Type0) (self : betree_List_t t) (x : t) : result (betree_List_t t) =
-  let tl = core_mem_replace (betree_List_t t) self Betree_List_Nil in
+  let (tl, _) = core_mem_replace (betree_List_t t) self Betree_List_Nil in
   let l = tl in
   Return (Betree_List_Cons x l)
 
-(** [betree_main::betree::{betree_main::betree::List<T>#1}::pop_front]: forward function
-    Source: 'src/betree.rs', lines 306:4-306:32 *)
-let betree_List_pop_front (t : Type0) (self : betree_List_t t) : result t =
-  let ls = core_mem_replace (betree_List_t t) self Betree_List_Nil in
-  begin match ls with
-  | Betree_List_Cons x tl -> Return x
-  | Betree_List_Nil -> Fail Failure
-  end
-
-(** [betree_main::betree::{betree_main::betree::List<T>#1}::pop_front]: backward function 0
+(** [betree_main::betree::{betree_main::betree::List<T>#1}::pop_front]:
     Source: 'src/betree.rs', lines 306:4-306:32 *)
-let betree_List_pop_front_back
-  (t : Type0) (self : betree_List_t t) : result (betree_List_t t) =
-  let ls = core_mem_replace (betree_List_t t) self Betree_List_Nil in
+let betree_List_pop_front
+  (t : Type0) (self : betree_List_t t) : result (t & (betree_List_t t)) =
+  let (ls, _) = core_mem_replace (betree_List_t t) self Betree_List_Nil in
   begin match ls with
-  | Betree_List_Cons x tl -> Return tl
+  | Betree_List_Cons x tl -> Return (x, tl)
   | Betree_List_Nil -> Fail Failure
   end
 
-(** [betree_main::betree::{betree_main::betree::List<T>#1}::hd]: forward function
+(** [betree_main::betree::{betree_main::betree::List<T>#1}::hd]:
     Source: 'src/betree.rs', lines 318:4-318:22 *)
 let betree_List_hd (t : Type0) (self : betree_List_t t) : result t =
   begin match self with
-  | Betree_List_Cons hd l -> Return hd
+  | Betree_List_Cons hd _ -> Return hd
   | Betree_List_Nil -> Fail Failure
   end
 
-(** [betree_main::betree::{betree_main::betree::List<(u64, T)>#2}::head_has_key]: forward function
+(** [betree_main::betree::{betree_main::betree::List<(u64, T)>#2}::head_has_key]:
     Source: 'src/betree.rs', lines 327:4-327:44 *)
 let betree_ListTupleU64T_head_has_key
   (t : Type0) (self : betree_List_t (u64 & t)) (key : u64) : result bool =
   begin match self with
-  | Betree_List_Cons hd l -> let (i, _) = hd in Return (i = key)
+  | Betree_List_Cons hd _ -> let (i, _) = hd in Return (i = key)
   | Betree_List_Nil -> Return false
   end
 
-(** [betree_main::betree::{betree_main::betree::List<(u64, T)>#2}::partition_at_pivot]: forward function
+(** [betree_main::betree::{betree_main::betree::List<(u64, T)>#2}::partition_at_pivot]:
     Source: 'src/betree.rs', lines 339:4-339:73 *)
 let rec betree_ListTupleU64T_partition_at_pivot
   (t : Type0) (self : betree_List_t (u64 & t)) (pivot : u64) :
@@ -183,119 +163,54 @@ let rec betree_ListTupleU64T_partition_at_pivot
   | Betree_List_Nil -> Return (Betree_List_Nil, Betree_List_Nil)
   end
 
-(** [betree_main::betree::{betree_main::betree::Leaf#3}::split]: forward function
+(** [betree_main::betree::{betree_main::betree::Leaf#3}::split]:
     Source: 'src/betree.rs', lines 359:4-364:17 *)
 let betree_Leaf_split
   (self : betree_Leaf_t) (content : betree_List_t (u64 & u64))
   (params : betree_Params_t) (node_id_cnt : betree_NodeIdCounter_t)
   (st : state) :
-  result (state & betree_Internal_t)
-  =
-  let* p = betree_List_split_at (u64 & u64) content params.split_size in
-  let (content0, content1) = p in
-  let* p0 = betree_List_hd (u64 & u64) content1 in
-  let (pivot, _) = p0 in
-  let* id0 = betree_NodeIdCounter_fresh_id node_id_cnt in
-  let* node_id_cnt0 = betree_NodeIdCounter_fresh_id_back node_id_cnt in
-  let* id1 = betree_NodeIdCounter_fresh_id node_id_cnt0 in
-  let* (st0, _) = betree_store_leaf_node id0 content0 st in
-  let* (st1, _) = betree_store_leaf_node id1 content1 st0 in
-  let n = Betree_Node_Leaf { id = id0; size = params.split_size } in
-  let n0 = Betree_Node_Leaf { id = id1; size = params.split_size } in
-  Return (st1, { id = self.id; pivot = pivot; left = n; right = n0 })
-
-(** [betree_main::betree::{betree_main::betree::Leaf#3}::split]: backward function 0
-    Source: 'src/betree.rs', lines 359:4-364:17 *)
-let betree_Leaf_split_back0
-  (self : betree_Leaf_t) (content : betree_List_t (u64 & u64))
-  (params : betree_Params_t) (node_id_cnt : betree_NodeIdCounter_t)
-  (st : state) (st0 : state) :
-  result (state & unit)
-  =
-  let* p = betree_List_split_at (u64 & u64) content params.split_size in
-  let (content0, content1) = p in
-  let* _ = betree_List_hd (u64 & u64) content1 in
-  let* id0 = betree_NodeIdCounter_fresh_id node_id_cnt in
-  let* node_id_cnt0 = betree_NodeIdCounter_fresh_id_back node_id_cnt in
-  let* id1 = betree_NodeIdCounter_fresh_id node_id_cnt0 in
-  let* (st1, _) = betree_store_leaf_node id0 content0 st in
-  let* _ = betree_store_leaf_node id1 content1 st1 in
-  Return (st0, ())
-
-(** [betree_main::betree::{betree_main::betree::Leaf#3}::split]: backward function 1
-    Source: 'src/betree.rs', lines 359:4-364:17 *)
-let betree_Leaf_split_back1
-  (self : betree_Leaf_t) (content : betree_List_t (u64 & u64))
-  (params : betree_Params_t) (node_id_cnt : betree_NodeIdCounter_t)
-  (st : state) (st0 : state) :
-  result (state & unit)
+  result (state & (betree_Internal_t & betree_NodeIdCounter_t))
   =
   let* p = betree_List_split_at (u64 & u64) content params.split_size in
   let (content0, content1) = p in
-  let* _ = betree_List_hd (u64 & u64) content1 in
-  let* id0 = betree_NodeIdCounter_fresh_id node_id_cnt in
-  let* node_id_cnt0 = betree_NodeIdCounter_fresh_id_back node_id_cnt in
-  let* id1 = betree_NodeIdCounter_fresh_id node_id_cnt0 in
+  let* p1 = betree_List_hd (u64 & u64) content1 in
+  let (pivot, _) = p1 in
+  let* (id0, nic) = betree_NodeIdCounter_fresh_id node_id_cnt in
+  let* (id1, nic1) = betree_NodeIdCounter_fresh_id nic in
   let* (st1, _) = betree_store_leaf_node id0 content0 st in
-  let* _ = betree_store_leaf_node id1 content1 st1 in
-  Return (st0, ())
-
-(** [betree_main::betree::{betree_main::betree::Leaf#3}::split]: backward function 2
-    Source: 'src/betree.rs', lines 359:4-364:17 *)
-let betree_Leaf_split_back2
-  (self : betree_Leaf_t) (content : betree_List_t (u64 & u64))
-  (params : betree_Params_t) (node_id_cnt : betree_NodeIdCounter_t)
-  (st : state) (st0 : state) :
-  result (state & betree_NodeIdCounter_t)
-  =
-  let* p = betree_List_split_at (u64 & u64) content params.split_size in
-  let (content0, content1) = p in
-  let* _ = betree_List_hd (u64 & u64) content1 in
-  let* id0 = betree_NodeIdCounter_fresh_id node_id_cnt in
-  let* node_id_cnt0 = betree_NodeIdCounter_fresh_id_back node_id_cnt in
-  let* id1 = betree_NodeIdCounter_fresh_id node_id_cnt0 in
-  let* (st1, _) = betree_store_leaf_node id0 content0 st in
-  let* _ = betree_store_leaf_node id1 content1 st1 in
-  let* node_id_cnt1 = betree_NodeIdCounter_fresh_id_back node_id_cnt0 in
-  Return (st0, node_id_cnt1)
+  let* (st2, _) = betree_store_leaf_node id1 content1 st1 in
+  let n = Betree_Node_Leaf { id = id0; size = params.split_size } in
+  let n1 = Betree_Node_Leaf { id = id1; size = params.split_size } in
+  Return (st2, ({ id = self.id; pivot = pivot; left = n; right = n1 }, nic1))
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_first_message_for_key]: forward function
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_first_message_for_key]:
     Source: 'src/betree.rs', lines 789:4-792:34 *)
 let rec betree_Node_lookup_first_message_for_key
   (key : u64) (msgs : betree_List_t (u64 & betree_Message_t)) :
-  Tot (result (betree_List_t (u64 & betree_Message_t)))
+  Tot (result ((betree_List_t (u64 & betree_Message_t)) & (betree_List_t (u64 &
+    betree_Message_t) -> result (betree_List_t (u64 & betree_Message_t)))))
   (decreases (betree_Node_lookup_first_message_for_key_decreases key msgs))
   =
   begin match msgs with
   | Betree_List_Cons x next_msgs ->
     let (i, m) = x in
     if i >= key
-    then Return (Betree_List_Cons (i, m) next_msgs)
-    else betree_Node_lookup_first_message_for_key key next_msgs
-  | Betree_List_Nil -> Return Betree_List_Nil
-  end
-
-(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_first_message_for_key]: backward function 0
-    Source: 'src/betree.rs', lines 789:4-792:34 *)
-let rec betree_Node_lookup_first_message_for_key_back
-  (key : u64) (msgs : betree_List_t (u64 & betree_Message_t))
-  (ret : betree_List_t (u64 & betree_Message_t)) :
-  Tot (result (betree_List_t (u64 & betree_Message_t)))
-  (decreases (betree_Node_lookup_first_message_for_key_decreases key msgs))
-  =
-  begin match msgs with
-  | Betree_List_Cons x next_msgs ->
-    let (i, m) = x in
-    if i >= key
-    then Return ret
+    then
+      let back_'a = fun ret -> Return ret in
+      Return (Betree_List_Cons (i, m) next_msgs, back_'a)
     else
-      let* next_msgs0 =
-        betree_Node_lookup_first_message_for_key_back key next_msgs ret in
-      Return (Betree_List_Cons (i, m) next_msgs0)
-  | Betree_List_Nil -> Return ret
+      let* (l, lookup_first_message_for_key_back) =
+        betree_Node_lookup_first_message_for_key key next_msgs in
+      let back_'a =
+        fun ret ->
+          let* next_msgs1 = lookup_first_message_for_key_back ret in
+          Return (Betree_List_Cons (i, m) next_msgs1) in
+      Return (l, back_'a)
+  | Betree_List_Nil ->
+    let back_'a = fun ret -> Return ret in Return (Betree_List_Nil, back_'a)
   end
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_in_bindings]: forward function
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_in_bindings]:
     Source: 'src/betree.rs', lines 636:4-636:80 *)
 let rec betree_Node_lookup_in_bindings
   (key : u64) (bindings : betree_List_t (u64 & u64)) :
@@ -304,221 +219,110 @@ let rec betree_Node_lookup_in_bindings
   =
   begin match bindings with
   | Betree_List_Cons hd tl ->
-    let (i, i0) = hd in
+    let (i, i1) = hd in
     if i = key
-    then Return (Some i0)
+    then Return (Some i1)
     else if i > key then Return None else betree_Node_lookup_in_bindings key tl
   | Betree_List_Nil -> Return None
   end
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply_upserts]: forward function
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_upserts]:
     Source: 'src/betree.rs', lines 819:4-819:90 *)
 let rec betree_Node_apply_upserts
   (msgs : betree_List_t (u64 & betree_Message_t)) (prev : option u64)
   (key : u64) (st : state) :
-  Tot (result (state & u64))
-  (decreases (betree_Node_apply_upserts_decreases msgs prev key st))
-  =
-  let* b = betree_ListTupleU64T_head_has_key betree_Message_t msgs key in
-  if b
-  then
-    let* msg = betree_List_pop_front (u64 & betree_Message_t) msgs in
-    let (_, m) = msg in
-    begin match m with
-    | Betree_Message_Insert i -> Fail Failure
-    | Betree_Message_Delete -> Fail Failure
-    | Betree_Message_Upsert s ->
-      let* v = betree_upsert_update prev s in
-      let* msgs0 = betree_List_pop_front_back (u64 & betree_Message_t) msgs in
-      betree_Node_apply_upserts msgs0 (Some v) key st
-    end
-  else
-    let* (st0, v) = core_option_Option_unwrap u64 prev st in
-    let* _ =
-      betree_List_push_front (u64 & betree_Message_t) msgs (key,
-        Betree_Message_Insert v) in
-    Return (st0, v)
-
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply_upserts]: backward function 0
-    Source: 'src/betree.rs', lines 819:4-819:90 *)
-let rec betree_Node_apply_upserts_back
-  (msgs : betree_List_t (u64 & betree_Message_t)) (prev : option u64)
-  (key : u64) (st : state) (st0 : state) :
-  Tot (result (state & (betree_List_t (u64 & betree_Message_t))))
+  Tot (result (state & (u64 & (betree_List_t (u64 & betree_Message_t)))))
   (decreases (betree_Node_apply_upserts_decreases msgs prev key st))
   =
   let* b = betree_ListTupleU64T_head_has_key betree_Message_t msgs key in
   if b
   then
-    let* msg = betree_List_pop_front (u64 & betree_Message_t) msgs in
+    let* (msg, l) = betree_List_pop_front (u64 & betree_Message_t) msgs in
     let (_, m) = msg in
     begin match m with
-    | Betree_Message_Insert i -> Fail Failure
+    | Betree_Message_Insert _ -> Fail Failure
     | Betree_Message_Delete -> Fail Failure
     | Betree_Message_Upsert s ->
       let* v = betree_upsert_update prev s in
-      let* msgs0 = betree_List_pop_front_back (u64 & betree_Message_t) msgs in
-      betree_Node_apply_upserts_back msgs0 (Some v) key st st0
+      betree_Node_apply_upserts l (Some v) key st
     end
   else
-    let* (_, v) = core_option_Option_unwrap u64 prev st in
-    let* msgs0 =
+    let* (st1, v) = core_option_Option_unwrap u64 prev st in
+    let* l =
       betree_List_push_front (u64 & betree_Message_t) msgs (key,
         Betree_Message_Insert v) in
-    Return (st0, msgs0)
+    Return (st1, (v, l))
 
-(** [betree_main::betree::{betree_main::betree::Internal#4}::lookup_in_children]: forward function
+(** [betree_main::betree::{betree_main::betree::Internal#4}::lookup_in_children]:
     Source: 'src/betree.rs', lines 395:4-395:63 *)
 let rec betree_Internal_lookup_in_children
   (self : betree_Internal_t) (key : u64) (st : state) :
-  Tot (result (state & (option u64)))
-  (decreases (betree_Internal_lookup_in_children_decreases self key st))
-  =
-  if key < self.pivot
-  then betree_Node_lookup self.left key st
-  else betree_Node_lookup self.right key st
-
-(** [betree_main::betree::{betree_main::betree::Internal#4}::lookup_in_children]: backward function 0
-    Source: 'src/betree.rs', lines 395:4-395:63 *)
-and betree_Internal_lookup_in_children_back
-  (self : betree_Internal_t) (key : u64) (st : state) (st0 : state) :
-  Tot (result (state & betree_Internal_t))
+  Tot (result (state & ((option u64) & betree_Internal_t)))
   (decreases (betree_Internal_lookup_in_children_decreases self key st))
   =
   if key < self.pivot
   then
-    let* (st1, n) = betree_Node_lookup_back self.left key st st0 in
-    Return (st1, { self with left = n })
+    let* (st1, (o, n)) = betree_Node_lookup self.left key st in
+    Return (st1, (o, { self with left = n }))
   else
-    let* (st1, n) = betree_Node_lookup_back self.right key st st0 in
-    Return (st1, { self with right = n })
+    let* (st1, (o, n)) = betree_Node_lookup self.right key st in
+    Return (st1, (o, { self with right = n }))
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::lookup]: forward function
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup]:
     Source: 'src/betree.rs', lines 709:4-709:58 *)
 and betree_Node_lookup
   (self : betree_Node_t) (key : u64) (st : state) :
-  Tot (result (state & (option u64)))
-  (decreases (betree_Node_lookup_decreases self key st))
-  =
-  begin match self with
-  | Betree_Node_Internal node ->
-    let* (st0, msgs) = betree_load_internal_node node.id st in
-    let* pending = betree_Node_lookup_first_message_for_key key msgs in
-    begin match pending with
-    | Betree_List_Cons p l ->
-      let (k, msg) = p in
-      if k <> key
-      then
-        let* (st1, o) = betree_Internal_lookup_in_children node key st0 in
-        let* _ =
-          betree_Node_lookup_first_message_for_key_back key msgs
-            (Betree_List_Cons (k, msg) l) in
-        Return (st1, o)
-      else
-        begin match msg with
-        | Betree_Message_Insert v ->
-          let* _ =
-            betree_Node_lookup_first_message_for_key_back key msgs
-              (Betree_List_Cons (k, Betree_Message_Insert v) l) in
-          Return (st0, Some v)
-        | Betree_Message_Delete ->
-          let* _ =
-            betree_Node_lookup_first_message_for_key_back key msgs
-              (Betree_List_Cons (k, Betree_Message_Delete) l) in
-          Return (st0, None)
-        | Betree_Message_Upsert ufs ->
-          let* (st1, v) = betree_Internal_lookup_in_children node key st0 in
-          let* (st2, v0) =
-            betree_Node_apply_upserts (Betree_List_Cons (k,
-              Betree_Message_Upsert ufs) l) v key st1 in
-          let* (st3, node0) =
-            betree_Internal_lookup_in_children_back node key st0 st2 in
-          let* (st4, pending0) =
-            betree_Node_apply_upserts_back (Betree_List_Cons (k,
-              Betree_Message_Upsert ufs) l) v key st1 st3 in
-          let* msgs0 =
-            betree_Node_lookup_first_message_for_key_back key msgs pending0 in
-          let* (st5, _) = betree_store_internal_node node0.id msgs0 st4 in
-          Return (st5, Some v0)
-        end
-    | Betree_List_Nil ->
-      let* (st1, o) = betree_Internal_lookup_in_children node key st0 in
-      let* _ =
-        betree_Node_lookup_first_message_for_key_back key msgs Betree_List_Nil
-        in
-      Return (st1, o)
-    end
-  | Betree_Node_Leaf node ->
-    let* (st0, bindings) = betree_load_leaf_node node.id st in
-    let* o = betree_Node_lookup_in_bindings key bindings in
-    Return (st0, o)
-  end
-
-(** [betree_main::betree::{betree_main::betree::Node#5}::lookup]: backward function 0
-    Source: 'src/betree.rs', lines 709:4-709:58 *)
-and betree_Node_lookup_back
-  (self : betree_Node_t) (key : u64) (st : state) (st0 : state) :
-  Tot (result (state & betree_Node_t))
+  Tot (result (state & ((option u64) & betree_Node_t)))
   (decreases (betree_Node_lookup_decreases self key st))
   =
   begin match self with
   | Betree_Node_Internal node ->
     let* (st1, msgs) = betree_load_internal_node node.id st in
-    let* pending = betree_Node_lookup_first_message_for_key key msgs in
+    let* (pending, lookup_first_message_for_key_back) =
+      betree_Node_lookup_first_message_for_key key msgs in
     begin match pending with
     | Betree_List_Cons p l ->
       let (k, msg) = p in
       if k <> key
       then
+        let* (st2, (o, i)) = betree_Internal_lookup_in_children node key st1 in
         let* _ =
-          betree_Node_lookup_first_message_for_key_back key msgs
-            (Betree_List_Cons (k, msg) l) in
-        let* (st2, node0) =
-          betree_Internal_lookup_in_children_back node key st1 st0 in
-        Return (st2, Betree_Node_Internal node0)
+          lookup_first_message_for_key_back (Betree_List_Cons (k, msg) l) in
+        Return (st2, (o, Betree_Node_Internal i))
       else
         begin match msg with
         | Betree_Message_Insert v ->
           let* _ =
-            betree_Node_lookup_first_message_for_key_back key msgs
-              (Betree_List_Cons (k, Betree_Message_Insert v) l) in
-          Return (st0, Betree_Node_Internal node)
+            lookup_first_message_for_key_back (Betree_List_Cons (k,
+              Betree_Message_Insert v) l) in
+          Return (st1, (Some v, Betree_Node_Internal node))
         | Betree_Message_Delete ->
           let* _ =
-            betree_Node_lookup_first_message_for_key_back key msgs
-              (Betree_List_Cons (k, Betree_Message_Delete) l) in
-          Return (st0, Betree_Node_Internal node)
+            lookup_first_message_for_key_back (Betree_List_Cons (k,
+              Betree_Message_Delete) l) in
+          Return (st1, (None, Betree_Node_Internal node))
         | Betree_Message_Upsert ufs ->
-          let* (st2, v) = betree_Internal_lookup_in_children node key st1 in
-          let* (st3, _) =
+          let* (st2, (v, i)) = betree_Internal_lookup_in_children node key st1
+            in
+          let* (st3, (v1, l1)) =
             betree_Node_apply_upserts (Betree_List_Cons (k,
               Betree_Message_Upsert ufs) l) v key st2 in
-          let* (st4, node0) =
-            betree_Internal_lookup_in_children_back node key st1 st3 in
-          let* (st5, pending0) =
-            betree_Node_apply_upserts_back (Betree_List_Cons (k,
-              Betree_Message_Upsert ufs) l) v key st2 st4 in
-          let* msgs0 =
-            betree_Node_lookup_first_message_for_key_back key msgs pending0 in
-          let* _ = betree_store_internal_node node0.id msgs0 st5 in
-          Return (st0, Betree_Node_Internal node0)
+          let* msgs1 = lookup_first_message_for_key_back l1 in
+          let* (st4, _) = betree_store_internal_node i.id msgs1 st3 in
+          Return (st4, (Some v1, Betree_Node_Internal i))
         end
     | Betree_List_Nil ->
-      let* _ =
-        betree_Node_lookup_first_message_for_key_back key msgs Betree_List_Nil
-        in
-      let* (st2, node0) =
-        betree_Internal_lookup_in_children_back node key st1 st0 in
-      Return (st2, Betree_Node_Internal node0)
+      let* (st2, (o, i)) = betree_Internal_lookup_in_children node key st1 in
+      let* _ = lookup_first_message_for_key_back Betree_List_Nil in
+      Return (st2, (o, Betree_Node_Internal i))
     end
   | Betree_Node_Leaf node ->
-    let* (_, bindings) = betree_load_leaf_node node.id st in
-    let* _ = betree_Node_lookup_in_bindings key bindings in
-    Return (st0, Betree_Node_Leaf node)
+    let* (st1, bindings) = betree_load_leaf_node node.id st in
+    let* o = betree_Node_lookup_in_bindings key bindings in
+    Return (st1, (o, Betree_Node_Leaf node))
   end
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::filter_messages_for_key]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [betree_main::betree::{betree_main::betree::Node#5}::filter_messages_for_key]:
     Source: 'src/betree.rs', lines 674:4-674:77 *)
 let rec betree_Node_filter_messages_for_key
   (key : u64) (msgs : betree_List_t (u64 & betree_Message_t)) :
@@ -530,36 +334,20 @@ let rec betree_Node_filter_messages_for_key
     let (k, m) = p in
     if k = key
     then
-      let* msgs0 =
-        betree_List_pop_front_back (u64 & betree_Message_t) (Betree_List_Cons
-          (k, m) l) in
-      betree_Node_filter_messages_for_key key msgs0
+      let* (_, l1) =
+        betree_List_pop_front (u64 & betree_Message_t) (Betree_List_Cons (k, m)
+          l) in
+      betree_Node_filter_messages_for_key key l1
     else Return (Betree_List_Cons (k, m) l)
   | Betree_List_Nil -> Return Betree_List_Nil
   end
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_first_message_after_key]: forward function
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_first_message_after_key]:
     Source: 'src/betree.rs', lines 689:4-692:34 *)
 let rec betree_Node_lookup_first_message_after_key
   (key : u64) (msgs : betree_List_t (u64 & betree_Message_t)) :
-  Tot (result (betree_List_t (u64 & betree_Message_t)))
-  (decreases (betree_Node_lookup_first_message_after_key_decreases key msgs))
-  =
-  begin match msgs with
-  | Betree_List_Cons p next_msgs ->
-    let (k, m) = p in
-    if k = key
-    then betree_Node_lookup_first_message_after_key key next_msgs
-    else Return (Betree_List_Cons (k, m) next_msgs)
-  | Betree_List_Nil -> Return Betree_List_Nil
-  end
-
-(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_first_message_after_key]: backward function 0
-    Source: 'src/betree.rs', lines 689:4-692:34 *)
-let rec betree_Node_lookup_first_message_after_key_back
-  (key : u64) (msgs : betree_List_t (u64 & betree_Message_t))
-  (ret : betree_List_t (u64 & betree_Message_t)) :
-  Tot (result (betree_List_t (u64 & betree_Message_t)))
+  Tot (result ((betree_List_t (u64 & betree_Message_t)) & (betree_List_t (u64 &
+    betree_Message_t) -> result (betree_List_t (u64 & betree_Message_t)))))
   (decreases (betree_Node_lookup_first_message_after_key_decreases key msgs))
   =
   begin match msgs with
@@ -567,75 +355,79 @@ let rec betree_Node_lookup_first_message_after_key_back
     let (k, m) = p in
     if k = key
     then
-      let* next_msgs0 =
-        betree_Node_lookup_first_message_after_key_back key next_msgs ret in
-      Return (Betree_List_Cons (k, m) next_msgs0)
-    else Return ret
-  | Betree_List_Nil -> Return ret
+      let* (l, lookup_first_message_after_key_back) =
+        betree_Node_lookup_first_message_after_key key next_msgs in
+      let back_'a =
+        fun ret ->
+          let* next_msgs1 = lookup_first_message_after_key_back ret in
+          Return (Betree_List_Cons (k, m) next_msgs1) in
+      Return (l, back_'a)
+    else
+      let back_'a = fun ret -> Return ret in
+      Return (Betree_List_Cons (k, m) next_msgs, back_'a)
+  | Betree_List_Nil ->
+    let back_'a = fun ret -> Return ret in Return (Betree_List_Nil, back_'a)
   end
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply_to_internal]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_to_internal]:
     Source: 'src/betree.rs', lines 521:4-521:89 *)
 let betree_Node_apply_to_internal
   (msgs : betree_List_t (u64 & betree_Message_t)) (key : u64)
   (new_msg : betree_Message_t) :
   result (betree_List_t (u64 & betree_Message_t))
   =
-  let* msgs0 = betree_Node_lookup_first_message_for_key key msgs in
-  let* b = betree_ListTupleU64T_head_has_key betree_Message_t msgs0 key in
+  let* (msgs1, lookup_first_message_for_key_back) =
+    betree_Node_lookup_first_message_for_key key msgs in
+  let* b = betree_ListTupleU64T_head_has_key betree_Message_t msgs1 key in
   if b
   then
     begin match new_msg with
     | Betree_Message_Insert i ->
-      let* msgs1 = betree_Node_filter_messages_for_key key msgs0 in
-      let* msgs2 =
-        betree_List_push_front (u64 & betree_Message_t) msgs1 (key,
+      let* l = betree_Node_filter_messages_for_key key msgs1 in
+      let* l1 =
+        betree_List_push_front (u64 & betree_Message_t) l (key,
           Betree_Message_Insert i) in
-      betree_Node_lookup_first_message_for_key_back key msgs msgs2
+      lookup_first_message_for_key_back l1
     | Betree_Message_Delete ->
-      let* msgs1 = betree_Node_filter_messages_for_key key msgs0 in
-      let* msgs2 =
-        betree_List_push_front (u64 & betree_Message_t) msgs1 (key,
+      let* l = betree_Node_filter_messages_for_key key msgs1 in
+      let* l1 =
+        betree_List_push_front (u64 & betree_Message_t) l (key,
           Betree_Message_Delete) in
-      betree_Node_lookup_first_message_for_key_back key msgs msgs2
+      lookup_first_message_for_key_back l1
     | Betree_Message_Upsert s ->
-      let* p = betree_List_hd (u64 & betree_Message_t) msgs0 in
+      let* p = betree_List_hd (u64 & betree_Message_t) msgs1 in
       let (_, m) = p in
       begin match m with
       | Betree_Message_Insert prev ->
         let* v = betree_upsert_update (Some prev) s in
-        let* msgs1 = betree_List_pop_front_back (u64 & betree_Message_t) msgs0
-          in
-        let* msgs2 =
-          betree_List_push_front (u64 & betree_Message_t) msgs1 (key,
+        let* (_, l) = betree_List_pop_front (u64 & betree_Message_t) msgs1 in
+        let* l1 =
+          betree_List_push_front (u64 & betree_Message_t) l (key,
             Betree_Message_Insert v) in
-        betree_Node_lookup_first_message_for_key_back key msgs msgs2
+        lookup_first_message_for_key_back l1
       | Betree_Message_Delete ->
+        let* (_, l) = betree_List_pop_front (u64 & betree_Message_t) msgs1 in
         let* v = betree_upsert_update None s in
-        let* msgs1 = betree_List_pop_front_back (u64 & betree_Message_t) msgs0
-          in
-        let* msgs2 =
-          betree_List_push_front (u64 & betree_Message_t) msgs1 (key,
+        let* l1 =
+          betree_List_push_front (u64 & betree_Message_t) l (key,
             Betree_Message_Insert v) in
-        betree_Node_lookup_first_message_for_key_back key msgs msgs2
-      | Betree_Message_Upsert ufs ->
-        let* msgs1 = betree_Node_lookup_first_message_after_key key msgs0 in
-        let* msgs2 =
-          betree_List_push_front (u64 & betree_Message_t) msgs1 (key,
+        lookup_first_message_for_key_back l1
+      | Betree_Message_Upsert _ ->
+        let* (msgs2, lookup_first_message_after_key_back) =
+          betree_Node_lookup_first_message_after_key key msgs1 in
+        let* l =
+          betree_List_push_front (u64 & betree_Message_t) msgs2 (key,
             Betree_Message_Upsert s) in
-        let* msgs3 =
-          betree_Node_lookup_first_message_after_key_back key msgs0 msgs2 in
-        betree_Node_lookup_first_message_for_key_back key msgs msgs3
+        let* msgs3 = lookup_first_message_after_key_back l in
+        lookup_first_message_for_key_back msgs3
       end
     end
   else
-    let* msgs1 =
-      betree_List_push_front (u64 & betree_Message_t) msgs0 (key, new_msg) in
-    betree_Node_lookup_first_message_for_key_back key msgs msgs1
+    let* l =
+      betree_List_push_front (u64 & betree_Message_t) msgs1 (key, new_msg) in
+    lookup_first_message_for_key_back l
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages_to_internal]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages_to_internal]:
     Source: 'src/betree.rs', lines 502:4-505:5 *)
 let rec betree_Node_apply_messages_to_internal
   (msgs : betree_List_t (u64 & betree_Message_t))
@@ -646,89 +438,75 @@ let rec betree_Node_apply_messages_to_internal
   begin match new_msgs with
   | Betree_List_Cons new_msg new_msgs_tl ->
     let (i, m) = new_msg in
-    let* msgs0 = betree_Node_apply_to_internal msgs i m in
-    betree_Node_apply_messages_to_internal msgs0 new_msgs_tl
+    let* l = betree_Node_apply_to_internal msgs i m in
+    betree_Node_apply_messages_to_internal l new_msgs_tl
   | Betree_List_Nil -> Return msgs
   end
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_mut_in_bindings]: forward function
+(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_mut_in_bindings]:
     Source: 'src/betree.rs', lines 653:4-656:32 *)
 let rec betree_Node_lookup_mut_in_bindings
   (key : u64) (bindings : betree_List_t (u64 & u64)) :
-  Tot (result (betree_List_t (u64 & u64)))
+  Tot (result ((betree_List_t (u64 & u64)) & (betree_List_t (u64 & u64) ->
+    result (betree_List_t (u64 & u64)))))
   (decreases (betree_Node_lookup_mut_in_bindings_decreases key bindings))
   =
   begin match bindings with
   | Betree_List_Cons hd tl ->
-    let (i, i0) = hd in
+    let (i, i1) = hd in
     if i >= key
-    then Return (Betree_List_Cons (i, i0) tl)
-    else betree_Node_lookup_mut_in_bindings key tl
-  | Betree_List_Nil -> Return Betree_List_Nil
-  end
-
-(** [betree_main::betree::{betree_main::betree::Node#5}::lookup_mut_in_bindings]: backward function 0
-    Source: 'src/betree.rs', lines 653:4-656:32 *)
-let rec betree_Node_lookup_mut_in_bindings_back
-  (key : u64) (bindings : betree_List_t (u64 & u64))
-  (ret : betree_List_t (u64 & u64)) :
-  Tot (result (betree_List_t (u64 & u64)))
-  (decreases (betree_Node_lookup_mut_in_bindings_decreases key bindings))
-  =
-  begin match bindings with
-  | Betree_List_Cons hd tl ->
-    let (i, i0) = hd in
-    if i >= key
-    then Return ret
+    then
+      let back_'a = fun ret -> Return ret in
+      Return (Betree_List_Cons (i, i1) tl, back_'a)
     else
-      let* tl0 = betree_Node_lookup_mut_in_bindings_back key tl ret in
-      Return (Betree_List_Cons (i, i0) tl0)
-  | Betree_List_Nil -> Return ret
+      let* (l, lookup_mut_in_bindings_back) =
+        betree_Node_lookup_mut_in_bindings key tl in
+      let back_'a =
+        fun ret ->
+          let* tl1 = lookup_mut_in_bindings_back ret in
+          Return (Betree_List_Cons (i, i1) tl1) in
+      Return (l, back_'a)
+  | Betree_List_Nil ->
+    let back_'a = fun ret -> Return ret in Return (Betree_List_Nil, back_'a)
   end
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply_to_leaf]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_to_leaf]:
     Source: 'src/betree.rs', lines 460:4-460:87 *)
 let betree_Node_apply_to_leaf
   (bindings : betree_List_t (u64 & u64)) (key : u64)
   (new_msg : betree_Message_t) :
   result (betree_List_t (u64 & u64))
   =
-  let* bindings0 = betree_Node_lookup_mut_in_bindings key bindings in
-  let* b = betree_ListTupleU64T_head_has_key u64 bindings0 key in
+  let* (bindings1, lookup_mut_in_bindings_back) =
+    betree_Node_lookup_mut_in_bindings key bindings in
+  let* b = betree_ListTupleU64T_head_has_key u64 bindings1 key in
   if b
   then
-    let* hd = betree_List_pop_front (u64 & u64) bindings0 in
+    let* (hd, l) = betree_List_pop_front (u64 & u64) bindings1 in
     begin match new_msg with
     | Betree_Message_Insert v ->
-      let* bindings1 = betree_List_pop_front_back (u64 & u64) bindings0 in
-      let* bindings2 = betree_List_push_front (u64 & u64) bindings1 (key, v) in
-      betree_Node_lookup_mut_in_bindings_back key bindings bindings2
-    | Betree_Message_Delete ->
-      let* bindings1 = betree_List_pop_front_back (u64 & u64) bindings0 in
-      betree_Node_lookup_mut_in_bindings_back key bindings bindings1
+      let* l1 = betree_List_push_front (u64 & u64) l (key, v) in
+      lookup_mut_in_bindings_back l1
+    | Betree_Message_Delete -> lookup_mut_in_bindings_back l
     | Betree_Message_Upsert s ->
       let (_, i) = hd in
       let* v = betree_upsert_update (Some i) s in
-      let* bindings1 = betree_List_pop_front_back (u64 & u64) bindings0 in
-      let* bindings2 = betree_List_push_front (u64 & u64) bindings1 (key, v) in
-      betree_Node_lookup_mut_in_bindings_back key bindings bindings2
+      let* l1 = betree_List_push_front (u64 & u64) l (key, v) in
+      lookup_mut_in_bindings_back l1
     end
   else
     begin match new_msg with
     | Betree_Message_Insert v ->
-      let* bindings1 = betree_List_push_front (u64 & u64) bindings0 (key, v) in
-      betree_Node_lookup_mut_in_bindings_back key bindings bindings1
-    | Betree_Message_Delete ->
-      betree_Node_lookup_mut_in_bindings_back key bindings bindings0
+      let* l = betree_List_push_front (u64 & u64) bindings1 (key, v) in
+      lookup_mut_in_bindings_back l
+    | Betree_Message_Delete -> lookup_mut_in_bindings_back bindings1
     | Betree_Message_Upsert s ->
       let* v = betree_upsert_update None s in
-      let* bindings1 = betree_List_push_front (u64 & u64) bindings0 (key, v) in
-      betree_Node_lookup_mut_in_bindings_back key bindings bindings1
+      let* l = betree_List_push_front (u64 & u64) bindings1 (key, v) in
+      lookup_mut_in_bindings_back l
     end
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages_to_leaf]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages_to_leaf]:
     Source: 'src/betree.rs', lines 444:4-447:5 *)
 let rec betree_Node_apply_messages_to_leaf
   (bindings : betree_List_t (u64 & u64))
@@ -739,69 +517,19 @@ let rec betree_Node_apply_messages_to_leaf
   begin match new_msgs with
   | Betree_List_Cons new_msg new_msgs_tl ->
     let (i, m) = new_msg in
-    let* bindings0 = betree_Node_apply_to_leaf bindings i m in
-    betree_Node_apply_messages_to_leaf bindings0 new_msgs_tl
+    let* l = betree_Node_apply_to_leaf bindings i m in
+    betree_Node_apply_messages_to_leaf l new_msgs_tl
   | Betree_List_Nil -> Return bindings
   end
 
-(** [betree_main::betree::{betree_main::betree::Internal#4}::flush]: forward function
+(** [betree_main::betree::{betree_main::betree::Internal#4}::flush]:
     Source: 'src/betree.rs', lines 410:4-415:26 *)
 let rec betree_Internal_flush
   (self : betree_Internal_t) (params : betree_Params_t)
   (node_id_cnt : betree_NodeIdCounter_t)
   (content : betree_List_t (u64 & betree_Message_t)) (st : state) :
-  Tot (result (state & (betree_List_t (u64 & betree_Message_t))))
-  (decreases (
-    betree_Internal_flush_decreases self params node_id_cnt content st))
-  =
-  let* p =
-    betree_ListTupleU64T_partition_at_pivot betree_Message_t content self.pivot
-    in
-  let (msgs_left, msgs_right) = p in
-  let* len_left = betree_List_len (u64 & betree_Message_t) msgs_left in
-  if len_left >= params.min_flush_size
-  then
-    let* (st0, _) =
-      betree_Node_apply_messages self.left params node_id_cnt msgs_left st in
-    let* (st1, (_, node_id_cnt0)) =
-      betree_Node_apply_messages_back'a self.left params node_id_cnt msgs_left
-        st st0 in
-    let* (st2, ()) =
-      betree_Node_apply_messages_back1 self.left params node_id_cnt msgs_left
-        st st1 in
-    let* len_right = betree_List_len (u64 & betree_Message_t) msgs_right in
-    if len_right >= params.min_flush_size
-    then
-      let* (st3, _) =
-        betree_Node_apply_messages self.right params node_id_cnt0 msgs_right
-          st2 in
-      let* (st4, (_, _)) =
-        betree_Node_apply_messages_back'a self.right params node_id_cnt0
-          msgs_right st2 st3 in
-      let* (st5, ()) =
-        betree_Node_apply_messages_back1 self.right params node_id_cnt0
-          msgs_right st2 st4 in
-      Return (st5, Betree_List_Nil)
-    else Return (st2, msgs_right)
-  else
-    let* (st0, _) =
-      betree_Node_apply_messages self.right params node_id_cnt msgs_right st in
-    let* (st1, (_, _)) =
-      betree_Node_apply_messages_back'a self.right params node_id_cnt
-        msgs_right st st0 in
-    let* (st2, ()) =
-      betree_Node_apply_messages_back1 self.right params node_id_cnt msgs_right
-        st st1 in
-    Return (st2, msgs_left)
-
-(** [betree_main::betree::{betree_main::betree::Internal#4}::flush]: backward function 0
-    Source: 'src/betree.rs', lines 410:4-415:26 *)
-and betree_Internal_flush_back'a
-  (self : betree_Internal_t) (params : betree_Params_t)
-  (node_id_cnt : betree_NodeIdCounter_t)
-  (content : betree_List_t (u64 & betree_Message_t)) (st : state) (st0 : state)
-  :
-  Tot (result (state & (betree_Internal_t & betree_NodeIdCounter_t)))
+  Tot (result (state & ((betree_List_t (u64 & betree_Message_t)) &
+    (betree_Internal_t & betree_NodeIdCounter_t))))
   (decreases (
     betree_Internal_flush_decreases self params node_id_cnt content st))
   =
@@ -812,138 +540,31 @@ and betree_Internal_flush_back'a
   let* len_left = betree_List_len (u64 & betree_Message_t) msgs_left in
   if len_left >= params.min_flush_size
   then
-    let* (st1, _) =
+    let* (st1, p1) =
       betree_Node_apply_messages self.left params node_id_cnt msgs_left st in
-    let* (st2, (n, node_id_cnt0)) =
-      betree_Node_apply_messages_back'a self.left params node_id_cnt msgs_left
-        st st1 in
-    let* (st3, ()) =
-      betree_Node_apply_messages_back1 self.left params node_id_cnt msgs_left
-        st st2 in
+    let (n, node_id_cnt1) = p1 in
     let* len_right = betree_List_len (u64 & betree_Message_t) msgs_right in
     if len_right >= params.min_flush_size
     then
-      let* (st4, _) =
-        betree_Node_apply_messages self.right params node_id_cnt0 msgs_right
-          st3 in
-      let* (st5, (n0, node_id_cnt1)) =
-        betree_Node_apply_messages_back'a self.right params node_id_cnt0
-          msgs_right st3 st4 in
-      let* _ =
-        betree_Node_apply_messages_back1 self.right params node_id_cnt0
-          msgs_right st3 st5 in
-      Return (st0, ({ self with left = n; right = n0 }, node_id_cnt1))
-    else Return (st0, ({ self with left = n }, node_id_cnt0))
+      let* (st2, p2) =
+        betree_Node_apply_messages self.right params node_id_cnt1 msgs_right
+          st1 in
+      let (n1, node_id_cnt2) = p2 in
+      Return (st2, (Betree_List_Nil, ({ self with left = n; right = n1 },
+        node_id_cnt2)))
+    else Return (st1, (msgs_right, ({ self with left = n }, node_id_cnt1)))
   else
-    let* (st1, _) =
+    let* (st1, p1) =
       betree_Node_apply_messages self.right params node_id_cnt msgs_right st in
-    let* (st2, (n, node_id_cnt0)) =
-      betree_Node_apply_messages_back'a self.right params node_id_cnt
-        msgs_right st st1 in
-    let* _ =
-      betree_Node_apply_messages_back1 self.right params node_id_cnt msgs_right
-        st st2 in
-    Return (st0, ({ self with right = n }, node_id_cnt0))
+    let (n, node_id_cnt1) = p1 in
+    Return (st1, (msgs_left, ({ self with right = n }, node_id_cnt1)))
 
-(** [betree_main::betree::{betree_main::betree::Internal#4}::flush]: backward function 1
-    Source: 'src/betree.rs', lines 410:4-415:26 *)
-and betree_Internal_flush_back1
-  (self : betree_Internal_t) (params : betree_Params_t)
-  (node_id_cnt : betree_NodeIdCounter_t)
-  (content : betree_List_t (u64 & betree_Message_t)) (st : state) (st0 : state)
-  :
-  Tot (result (state & unit))
-  (decreases (
-    betree_Internal_flush_decreases self params node_id_cnt content st))
-  =
-  let* p =
-    betree_ListTupleU64T_partition_at_pivot betree_Message_t content self.pivot
-    in
-  let (msgs_left, msgs_right) = p in
-  let* len_left = betree_List_len (u64 & betree_Message_t) msgs_left in
-  if len_left >= params.min_flush_size
-  then
-    let* (st1, _) =
-      betree_Node_apply_messages self.left params node_id_cnt msgs_left st in
-    let* (st2, (_, node_id_cnt0)) =
-      betree_Node_apply_messages_back'a self.left params node_id_cnt msgs_left
-        st st1 in
-    let* (st3, ()) =
-      betree_Node_apply_messages_back1 self.left params node_id_cnt msgs_left
-        st st2 in
-    let* len_right = betree_List_len (u64 & betree_Message_t) msgs_right in
-    if len_right >= params.min_flush_size
-    then
-      let* (st4, _) =
-        betree_Node_apply_messages self.right params node_id_cnt0 msgs_right
-          st3 in
-      let* (st5, (_, _)) =
-        betree_Node_apply_messages_back'a self.right params node_id_cnt0
-          msgs_right st3 st4 in
-      let* _ =
-        betree_Node_apply_messages_back1 self.right params node_id_cnt0
-          msgs_right st3 st5 in
-      Return (st0, ())
-    else Return (st0, ())
-  else
-    let* (st1, _) =
-      betree_Node_apply_messages self.right params node_id_cnt msgs_right st in
-    let* (st2, (_, _)) =
-      betree_Node_apply_messages_back'a self.right params node_id_cnt
-        msgs_right st st1 in
-    let* _ =
-      betree_Node_apply_messages_back1 self.right params node_id_cnt msgs_right
-        st st2 in
-    Return (st0, ())
-
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages]: forward function
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages]:
     Source: 'src/betree.rs', lines 588:4-593:5 *)
 and betree_Node_apply_messages
   (self : betree_Node_t) (params : betree_Params_t)
   (node_id_cnt : betree_NodeIdCounter_t)
   (msgs : betree_List_t (u64 & betree_Message_t)) (st : state) :
-  Tot (result (state & unit))
-  (decreases (
-    betree_Node_apply_messages_decreases self params node_id_cnt msgs st))
-  =
-  begin match self with
-  | Betree_Node_Internal node ->
-    let* (st0, content) = betree_load_internal_node node.id st in
-    let* content0 = betree_Node_apply_messages_to_internal content msgs in
-    let* num_msgs = betree_List_len (u64 & betree_Message_t) content0 in
-    if num_msgs >= params.min_flush_size
-    then
-      let* (st1, content1) =
-        betree_Internal_flush node params node_id_cnt content0 st0 in
-      let* (st2, (node0, _)) =
-        betree_Internal_flush_back'a node params node_id_cnt content0 st0 st1
-        in
-      let* (st3, _) = betree_store_internal_node node0.id content1 st2 in
-      Return (st3, ())
-    else
-      let* (st1, _) = betree_store_internal_node node.id content0 st0 in
-      Return (st1, ())
-  | Betree_Node_Leaf node ->
-    let* (st0, content) = betree_load_leaf_node node.id st in
-    let* content0 = betree_Node_apply_messages_to_leaf content msgs in
-    let* len = betree_List_len (u64 & u64) content0 in
-    let* i = u64_mul 2 params.split_size in
-    if len >= i
-    then
-      let* (st1, _) = betree_Leaf_split node content0 params node_id_cnt st0 in
-      let* (st2, _) = betree_store_leaf_node node.id Betree_List_Nil st1 in
-      betree_Leaf_split_back0 node content0 params node_id_cnt st0 st2
-    else
-      let* (st1, _) = betree_store_leaf_node node.id content0 st0 in
-      Return (st1, ())
-  end
-
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages]: backward function 0
-    Source: 'src/betree.rs', lines 588:4-593:5 *)
-and betree_Node_apply_messages_back'a
-  (self : betree_Node_t) (params : betree_Params_t)
-  (node_id_cnt : betree_NodeIdCounter_t)
-  (msgs : betree_List_t (u64 & betree_Message_t)) (st : state) (st0 : state) :
   Tot (result (state & (betree_Node_t & betree_NodeIdCounter_t)))
   (decreases (
     betree_Node_apply_messages_decreases self params node_id_cnt msgs st))
@@ -951,277 +572,111 @@ and betree_Node_apply_messages_back'a
   begin match self with
   | Betree_Node_Internal node ->
     let* (st1, content) = betree_load_internal_node node.id st in
-    let* content0 = betree_Node_apply_messages_to_internal content msgs in
-    let* num_msgs = betree_List_len (u64 & betree_Message_t) content0 in
-    if num_msgs >= params.min_flush_size
-    then
-      let* (st2, content1) =
-        betree_Internal_flush node params node_id_cnt content0 st1 in
-      let* (st3, (node0, node_id_cnt0)) =
-        betree_Internal_flush_back'a node params node_id_cnt content0 st1 st2
-        in
-      let* _ = betree_store_internal_node node0.id content1 st3 in
-      Return (st0, (Betree_Node_Internal node0, node_id_cnt0))
-    else
-      let* _ = betree_store_internal_node node.id content0 st1 in
-      Return (st0, (Betree_Node_Internal node, node_id_cnt))
-  | Betree_Node_Leaf node ->
-    let* (st1, content) = betree_load_leaf_node node.id st in
-    let* content0 = betree_Node_apply_messages_to_leaf content msgs in
-    let* len = betree_List_len (u64 & u64) content0 in
-    let* i = u64_mul 2 params.split_size in
-    if len >= i
-    then
-      let* (st2, new_node) =
-        betree_Leaf_split node content0 params node_id_cnt st1 in
-      let* (st3, _) = betree_store_leaf_node node.id Betree_List_Nil st2 in
-      let* _ = betree_Leaf_split_back0 node content0 params node_id_cnt st1 st3
-        in
-      let* (st4, node_id_cnt0) =
-        betree_Leaf_split_back2 node content0 params node_id_cnt st1 st0 in
-      Return (st4, (Betree_Node_Internal new_node, node_id_cnt0))
-    else
-      let* _ = betree_store_leaf_node node.id content0 st1 in
-      Return (st0, (Betree_Node_Leaf { node with size = len }, node_id_cnt))
-  end
-
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply_messages]: backward function 1
-    Source: 'src/betree.rs', lines 588:4-593:5 *)
-and betree_Node_apply_messages_back1
-  (self : betree_Node_t) (params : betree_Params_t)
-  (node_id_cnt : betree_NodeIdCounter_t)
-  (msgs : betree_List_t (u64 & betree_Message_t)) (st : state) (st0 : state) :
-  Tot (result (state & unit))
-  (decreases (
-    betree_Node_apply_messages_decreases self params node_id_cnt msgs st))
-  =
-  begin match self with
-  | Betree_Node_Internal node ->
-    let* (st1, content) = betree_load_internal_node node.id st in
-    let* content0 = betree_Node_apply_messages_to_internal content msgs in
-    let* num_msgs = betree_List_len (u64 & betree_Message_t) content0 in
+    let* l = betree_Node_apply_messages_to_internal content msgs in
+    let* num_msgs = betree_List_len (u64 & betree_Message_t) l in
     if num_msgs >= params.min_flush_size
     then
-      let* (st2, content1) =
-        betree_Internal_flush node params node_id_cnt content0 st1 in
-      let* (st3, (node0, _)) =
-        betree_Internal_flush_back'a node params node_id_cnt content0 st1 st2
-        in
-      let* _ = betree_store_internal_node node0.id content1 st3 in
-      betree_Internal_flush_back1 node params node_id_cnt content0 st1 st0
+      let* (st2, (content1, p)) =
+        betree_Internal_flush node params node_id_cnt l st1 in
+      let (node1, node_id_cnt1) = p in
+      let* (st3, _) = betree_store_internal_node node1.id content1 st2 in
+      Return (st3, (Betree_Node_Internal node1, node_id_cnt1))
     else
-      let* _ = betree_store_internal_node node.id content0 st1 in
-      Return (st0, ())
+      let* (st2, _) = betree_store_internal_node node.id l st1 in
+      Return (st2, (Betree_Node_Internal node, node_id_cnt))
   | Betree_Node_Leaf node ->
     let* (st1, content) = betree_load_leaf_node node.id st in
-    let* content0 = betree_Node_apply_messages_to_leaf content msgs in
-    let* len = betree_List_len (u64 & u64) content0 in
+    let* l = betree_Node_apply_messages_to_leaf content msgs in
+    let* len = betree_List_len (u64 & u64) l in
     let* i = u64_mul 2 params.split_size in
     if len >= i
     then
-      let* (st2, _) = betree_Leaf_split node content0 params node_id_cnt st1 in
+      let* (st2, (new_node, nic)) =
+        betree_Leaf_split node l params node_id_cnt st1 in
       let* (st3, _) = betree_store_leaf_node node.id Betree_List_Nil st2 in
-      let* _ = betree_Leaf_split_back0 node content0 params node_id_cnt st1 st3
-        in
-      betree_Leaf_split_back1 node content0 params node_id_cnt st1 st0
+      Return (st3, (Betree_Node_Internal new_node, nic))
     else
-      let* _ = betree_store_leaf_node node.id content0 st1 in Return (st0, ())
+      let* (st2, _) = betree_store_leaf_node node.id l st1 in
+      Return (st2, (Betree_Node_Leaf { node with size = len }, node_id_cnt))
   end
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply]: forward function
+(** [betree_main::betree::{betree_main::betree::Node#5}::apply]:
     Source: 'src/betree.rs', lines 576:4-582:5 *)
 let betree_Node_apply
   (self : betree_Node_t) (params : betree_Params_t)
   (node_id_cnt : betree_NodeIdCounter_t) (key : u64)
   (new_msg : betree_Message_t) (st : state) :
-  result (state & unit)
-  =
-  let l = Betree_List_Nil in
-  let* (st0, _) =
-    betree_Node_apply_messages self params node_id_cnt (Betree_List_Cons (key,
-      new_msg) l) st in
-  let* (st1, (_, _)) =
-    betree_Node_apply_messages_back'a self params node_id_cnt (Betree_List_Cons
-      (key, new_msg) l) st st0 in
-  betree_Node_apply_messages_back1 self params node_id_cnt (Betree_List_Cons
-    (key, new_msg) l) st st1
-
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply]: backward function 0
-    Source: 'src/betree.rs', lines 576:4-582:5 *)
-let betree_Node_apply_back'a
-  (self : betree_Node_t) (params : betree_Params_t)
-  (node_id_cnt : betree_NodeIdCounter_t) (key : u64)
-  (new_msg : betree_Message_t) (st : state) (st0 : state) :
   result (state & (betree_Node_t & betree_NodeIdCounter_t))
   =
   let l = Betree_List_Nil in
-  let* (st1, _) =
+  let* (st1, p) =
     betree_Node_apply_messages self params node_id_cnt (Betree_List_Cons (key,
       new_msg) l) st in
-  let* (st2, (self0, node_id_cnt0)) =
-    betree_Node_apply_messages_back'a self params node_id_cnt (Betree_List_Cons
-      (key, new_msg) l) st st1 in
-  let* _ =
-    betree_Node_apply_messages_back1 self params node_id_cnt (Betree_List_Cons
-      (key, new_msg) l) st st2 in
-  Return (st0, (self0, node_id_cnt0))
+  let (self1, node_id_cnt1) = p in
+  Return (st1, (self1, node_id_cnt1))
 
-(** [betree_main::betree::{betree_main::betree::Node#5}::apply]: backward function 1
-    Source: 'src/betree.rs', lines 576:4-582:5 *)
-let betree_Node_apply_back1
-  (self : betree_Node_t) (params : betree_Params_t)
-  (node_id_cnt : betree_NodeIdCounter_t) (key : u64)
-  (new_msg : betree_Message_t) (st : state) (st0 : state) :
-  result (state & unit)
-  =
-  let l = Betree_List_Nil in
-  let* (st1, _) =
-    betree_Node_apply_messages self params node_id_cnt (Betree_List_Cons (key,
-      new_msg) l) st in
-  let* (st2, (_, _)) =
-    betree_Node_apply_messages_back'a self params node_id_cnt (Betree_List_Cons
-      (key, new_msg) l) st st1 in
-  let* _ =
-    betree_Node_apply_messages_back1 self params node_id_cnt (Betree_List_Cons
-      (key, new_msg) l) st st2 in
-  Return (st0, ())
-
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::new]: forward function
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::new]:
     Source: 'src/betree.rs', lines 849:4-849:60 *)
 let betree_BeTree_new
   (min_flush_size : u64) (split_size : u64) (st : state) :
   result (state & betree_BeTree_t)
   =
   let* node_id_cnt = betree_NodeIdCounter_new in
-  let* id = betree_NodeIdCounter_fresh_id node_id_cnt in
-  let* (st0, _) = betree_store_leaf_node id Betree_List_Nil st in
-  let* node_id_cnt0 = betree_NodeIdCounter_fresh_id_back node_id_cnt in
-  Return (st0,
+  let* (id, nic) = betree_NodeIdCounter_fresh_id node_id_cnt in
+  let* (st1, _) = betree_store_leaf_node id Betree_List_Nil st in
+  Return (st1,
     {
       params = { min_flush_size = min_flush_size; split_size = split_size };
-      node_id_cnt = node_id_cnt0;
+      node_id_cnt = nic;
       root = (Betree_Node_Leaf { id = id; size = 0 })
     })
 
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::apply]: forward function
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::apply]:
     Source: 'src/betree.rs', lines 868:4-868:47 *)
 let betree_BeTree_apply
   (self : betree_BeTree_t) (key : u64) (msg : betree_Message_t) (st : state) :
-  result (state & unit)
-  =
-  let* (st0, _) =
-    betree_Node_apply self.root self.params self.node_id_cnt key msg st in
-  let* (st1, (_, _)) =
-    betree_Node_apply_back'a self.root self.params self.node_id_cnt key msg st
-      st0 in
-  betree_Node_apply_back1 self.root self.params self.node_id_cnt key msg st st1
-
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::apply]: backward function 0
-    Source: 'src/betree.rs', lines 868:4-868:47 *)
-let betree_BeTree_apply_back
-  (self : betree_BeTree_t) (key : u64) (msg : betree_Message_t) (st : state)
-  (st0 : state) :
   result (state & betree_BeTree_t)
   =
-  let* (st1, _) =
+  let* (st1, p) =
     betree_Node_apply self.root self.params self.node_id_cnt key msg st in
-  let* (st2, (n, nic)) =
-    betree_Node_apply_back'a self.root self.params self.node_id_cnt key msg st
-      st1 in
-  let* _ =
-    betree_Node_apply_back1 self.root self.params self.node_id_cnt key msg st
-      st2 in
-  Return (st0, { self with node_id_cnt = nic; root = n })
+  let (n, nic) = p in
+  Return (st1, { self with node_id_cnt = nic; root = n })
 
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::insert]: forward function
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::insert]:
     Source: 'src/betree.rs', lines 874:4-874:52 *)
 let betree_BeTree_insert
   (self : betree_BeTree_t) (key : u64) (value : u64) (st : state) :
-  result (state & unit)
-  =
-  let* (st0, _) = betree_BeTree_apply self key (Betree_Message_Insert value) st
-    in
-  let* (st1, _) =
-    betree_BeTree_apply_back self key (Betree_Message_Insert value) st st0 in
-  Return (st1, ())
-
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::insert]: backward function 0
-    Source: 'src/betree.rs', lines 874:4-874:52 *)
-let betree_BeTree_insert_back
-  (self : betree_BeTree_t) (key : u64) (value : u64) (st : state) (st0 : state)
-  :
   result (state & betree_BeTree_t)
   =
-  let* (st1, _) = betree_BeTree_apply self key (Betree_Message_Insert value) st
-    in
-  let* (_, self0) =
-    betree_BeTree_apply_back self key (Betree_Message_Insert value) st st1 in
-  Return (st0, self0)
+  betree_BeTree_apply self key (Betree_Message_Insert value) st
 
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::delete]: forward function
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::delete]:
     Source: 'src/betree.rs', lines 880:4-880:38 *)
 let betree_BeTree_delete
-  (self : betree_BeTree_t) (key : u64) (st : state) : result (state & unit) =
-  let* (st0, _) = betree_BeTree_apply self key Betree_Message_Delete st in
-  let* (st1, _) =
-    betree_BeTree_apply_back self key Betree_Message_Delete st st0 in
-  Return (st1, ())
-
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::delete]: backward function 0
-    Source: 'src/betree.rs', lines 880:4-880:38 *)
-let betree_BeTree_delete_back
-  (self : betree_BeTree_t) (key : u64) (st : state) (st0 : state) :
+  (self : betree_BeTree_t) (key : u64) (st : state) :
   result (state & betree_BeTree_t)
   =
-  let* (st1, _) = betree_BeTree_apply self key Betree_Message_Delete st in
-  let* (_, self0) =
-    betree_BeTree_apply_back self key Betree_Message_Delete st st1 in
-  Return (st0, self0)
+  betree_BeTree_apply self key Betree_Message_Delete st
 
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::upsert]: forward function
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::upsert]:
     Source: 'src/betree.rs', lines 886:4-886:59 *)
 let betree_BeTree_upsert
   (self : betree_BeTree_t) (key : u64) (upd : betree_UpsertFunState_t)
   (st : state) :
-  result (state & unit)
-  =
-  let* (st0, _) = betree_BeTree_apply self key (Betree_Message_Upsert upd) st
-    in
-  let* (st1, _) =
-    betree_BeTree_apply_back self key (Betree_Message_Upsert upd) st st0 in
-  Return (st1, ())
-
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::upsert]: backward function 0
-    Source: 'src/betree.rs', lines 886:4-886:59 *)
-let betree_BeTree_upsert_back
-  (self : betree_BeTree_t) (key : u64) (upd : betree_UpsertFunState_t)
-  (st : state) (st0 : state) :
   result (state & betree_BeTree_t)
   =
-  let* (st1, _) = betree_BeTree_apply self key (Betree_Message_Upsert upd) st
-    in
-  let* (_, self0) =
-    betree_BeTree_apply_back self key (Betree_Message_Upsert upd) st st1 in
-  Return (st0, self0)
+  betree_BeTree_apply self key (Betree_Message_Upsert upd) st
 
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::lookup]: forward function
+(** [betree_main::betree::{betree_main::betree::BeTree#6}::lookup]:
     Source: 'src/betree.rs', lines 895:4-895:62 *)
 let betree_BeTree_lookup
   (self : betree_BeTree_t) (key : u64) (st : state) :
-  result (state & (option u64))
-  =
-  betree_Node_lookup self.root key st
-
-(** [betree_main::betree::{betree_main::betree::BeTree#6}::lookup]: backward function 0
-    Source: 'src/betree.rs', lines 895:4-895:62 *)
-let betree_BeTree_lookup_back
-  (self : betree_BeTree_t) (key : u64) (st : state) (st0 : state) :
-  result (state & betree_BeTree_t)
+  result (state & ((option u64) & betree_BeTree_t))
   =
-  let* (st1, n) = betree_Node_lookup_back self.root key st st0 in
-  Return (st1, { self with root = n })
+  let* (st1, (o, n)) = betree_Node_lookup self.root key st in
+  Return (st1, (o, { self with root = n }))
 
-(** [betree_main::main]: forward function
+(** [betree_main::main]:
     Source: 'src/betree_main.rs', lines 5:0-5:9 *)
 let main : result unit =
   Return ()
diff --git a/tests/fstar/betree_back_stateful/BetreeMain.FunsExternal.fsti b/tests/fstar/betree_back_stateful/BetreeMain.FunsExternal.fsti
index cd2f956f..de9b96fd 100644
--- a/tests/fstar/betree_back_stateful/BetreeMain.FunsExternal.fsti
+++ b/tests/fstar/betree_back_stateful/BetreeMain.FunsExternal.fsti
@@ -6,29 +6,29 @@ include BetreeMain.Types
 
 #set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
 
-(** [betree_main::betree_utils::load_internal_node]: forward function
+(** [betree_main::betree_utils::load_internal_node]:
     Source: 'src/betree_utils.rs', lines 98:0-98:63 *)
 val betree_utils_load_internal_node
   : u64 -> state -> result (state & (betree_List_t (u64 & betree_Message_t)))
 
-(** [betree_main::betree_utils::store_internal_node]: forward function
+(** [betree_main::betree_utils::store_internal_node]:
     Source: 'src/betree_utils.rs', lines 115:0-115:71 *)
 val betree_utils_store_internal_node
   :
   u64 -> betree_List_t (u64 & betree_Message_t) -> state -> result (state &
     unit)
 
-(** [betree_main::betree_utils::load_leaf_node]: forward function
+(** [betree_main::betree_utils::load_leaf_node]:
     Source: 'src/betree_utils.rs', lines 132:0-132:55 *)
 val betree_utils_load_leaf_node
   : u64 -> state -> result (state & (betree_List_t (u64 & u64)))
 
-(** [betree_main::betree_utils::store_leaf_node]: forward function
+(** [betree_main::betree_utils::store_leaf_node]:
     Source: 'src/betree_utils.rs', lines 145:0-145:63 *)
 val betree_utils_store_leaf_node
   : u64 -> betree_List_t (u64 & u64) -> state -> result (state & unit)
 
-(** [core::option::{core::option::Option<T>}::unwrap]: forward function
+(** [core::option::{core::option::Option<T>}::unwrap]:
     Source: '/rustc/d59363ad0b6391b7fc5bbb02c9ccf9300eef3753/library/core/src/option.rs', lines 932:4-932:34 *)
 val core_option_Option_unwrap
   (t : Type0) : option t -> state -> result (state & t)
diff --git a/tests/fstar/betree_back_stateful/Primitives.fst b/tests/fstar/betree_back_stateful/Primitives.fst
index a3ffbde4..fca80829 100644
--- a/tests/fstar/betree_back_stateful/Primitives.fst
+++ b/tests/fstar/betree_back_stateful/Primitives.fst
@@ -55,8 +55,7 @@ type string = string
 let is_zero (n: nat) : bool = n = 0
 let decrease (n: nat{n > 0}) : nat = n - 1
 
-let core_mem_replace (a : Type0) (x : a) (y : a) : a = x
-let core_mem_replace_back (a : Type0) (x : a) (y : a) : a = y
+let core_mem_replace (a : Type0) (x : a) (y : a) : a & a = (x, x)
 
 // We don't really use raw pointers for now
 type mut_raw_ptr (t : Type0) = { v : t }
@@ -477,8 +476,7 @@ noeq type core_ops_index_Index (self idx : Type0) = {
 // Trait declaration: [core::ops::index::IndexMut]
 noeq type core_ops_index_IndexMut (self idx : Type0) = {
   indexInst : core_ops_index_Index self idx;
-  index_mut : self → idx → result indexInst.output;
-  index_mut_back : self → idx → indexInst.output → result self;
+  index_mut : self → idx → result (indexInst.output & (indexInst.output → result self));
 }
 
 // Trait declaration [core::ops::deref::Deref]
@@ -490,8 +488,7 @@ noeq type core_ops_deref_Deref (self : Type0) = {
 // Trait declaration [core::ops::deref::DerefMut]
 noeq type core_ops_deref_DerefMut (self : Type0) = {
   derefInst : core_ops_deref_Deref self;
-  deref_mut : self → result derefInst.target;
-  deref_mut_back : self → derefInst.target → result self;
+  deref_mut : self → result (derefInst.target & (derefInst.target → result self));
 }
 
 type core_ops_range_Range (a : Type0) = {
@@ -502,8 +499,8 @@ type core_ops_range_Range (a : Type0) = {
 (*** [alloc] *)
 
 let alloc_boxed_Box_deref (t : Type0) (x : t) : result t = Return x
-let alloc_boxed_Box_deref_mut (t : Type0) (x : t) : result t = Return x
-let alloc_boxed_Box_deref_mut_back (t : Type) (_ : t) (x : t) : result t = Return x
+let alloc_boxed_Box_deref_mut (t : Type0) (x : t) : result (t & (t -> result t)) =
+  Return (x, (fun x -> Return x))
 
 // Trait instance
 let alloc_boxed_Box_coreopsDerefInst (self : Type0) : core_ops_deref_Deref self = {
@@ -515,7 +512,6 @@ let alloc_boxed_Box_coreopsDerefInst (self : Type0) : core_ops_deref_Deref self
 let alloc_boxed_Box_coreopsDerefMutInst (self : Type0) : core_ops_deref_DerefMut self = {
   derefInst = alloc_boxed_Box_coreopsDerefInst self;
   deref_mut = alloc_boxed_Box_deref_mut self;
-  deref_mut_back = alloc_boxed_Box_deref_mut_back self;
 }
 
 (*** Array *)
@@ -535,10 +531,18 @@ let array_index_usize (a : Type0) (n : usize) (x : array a n) (i : usize) : resu
   if i < length x then Return (index x i)
   else Fail Failure
 
-let array_update_usize (a : Type0) (n : usize) (x : array a n) (i : usize) (nx : a) : result (array a n) =
+let array_update_usize (a : Type0) (n : usize) (x : array a n) (i : usize) (nx : a) :
+  result (array a n) =
   if i < length x then Return (list_update x i nx)
   else Fail Failure
 
+let array_index_mut_usize (a : Type0) (n : usize) (x : array a n) (i : usize) :
+  result (a & (a -> result (array a n))) =
+  match array_index_usize a n x i with
+  | Fail e -> Fail e
+  | Return v ->
+    Return (v, array_update_usize a n x i)
+
 (*** Slice *)
 type slice (a : Type0) = s:list a{length s <= usize_max}
 
@@ -552,6 +556,13 @@ let slice_update_usize (a : Type0) (x : slice a) (i : usize) (nx : a) : result (
   if i < length x then Return (list_update x i nx)
   else Fail Failure
 
+let slice_index_mut_usize (a : Type0) (s : slice a) (i : usize) :
+  result (a & (a -> result (slice a))) =
+  match slice_index_usize a s i with
+  | Fail e -> Fail e
+  | Return x ->
+    Return (x, slice_update_usize a s i)
+
 (*** Subslices *)
 
 let array_to_slice (a : Type0) (n : usize) (x : array a n) : result (slice a) = Return x
@@ -559,6 +570,10 @@ let array_from_slice (a : Type0) (n : usize) (x : array a n) (s : slice a) : res
   if length s = n then Return s
   else Fail Failure
 
+let array_to_slice_mut (a : Type0) (n : usize) (x : array a n) :
+  result (slice a & (slice a -> result (array a n))) =
+  Return (x, array_from_slice a n x)
+
 // TODO: finish the definitions below (there lacks [List.drop] and [List.take] in the standard library *)
 let array_subslice (a : Type0) (n : usize) (x : array a n) (r : core_ops_range_Range usize) : result (slice a) =
   admit()
@@ -588,8 +603,13 @@ let alloc_vec_Vec_index_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) : r
 let alloc_vec_Vec_update_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
   if i < length v then Return (list_update v i x) else Fail Failure
 
-// The **forward** function shouldn't be used
-let alloc_vec_Vec_push_fwd (a  : Type0) (v : alloc_vec_Vec a) (x : a) : unit = ()
+let alloc_vec_Vec_index_mut_usize (#a : Type0) (v: alloc_vec_Vec a) (i: usize) :
+  result (a & (a → result (alloc_vec_Vec a))) =
+  match alloc_vec_Vec_index_usize v i with
+  | Return x ->
+    Return (x, alloc_vec_Vec_update_usize v i)
+  | Fail e -> Fail e
+
 let alloc_vec_Vec_push (a  : Type0) (v : alloc_vec_Vec a) (x : a) :
   Pure (result (alloc_vec_Vec a))
   (requires True)
@@ -605,9 +625,6 @@ let alloc_vec_Vec_push (a  : Type0) (v : alloc_vec_Vec a) (x : a) :
     end
   else Fail Failure
 
-// The **forward** function shouldn't be used
-let alloc_vec_Vec_insert_fwd (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result unit =
-  if i < length v then Return () else Fail Failure
 let alloc_vec_Vec_insert (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
   if i < length v then Return (list_update v i x) else Fail Failure
 
@@ -619,13 +636,11 @@ noeq type core_slice_index_SliceIndex (self t : Type0) = {
   sealedInst : core_slice_index_private_slice_index_Sealed self;
   output : Type0;
   get : self → t → result (option output);
-  get_mut : self → t → result (option output);
-  get_mut_back : self → t → option output → result t;
+  get_mut : self → t → result (option output & (option output -> result t));
   get_unchecked : self → const_raw_ptr t → result (const_raw_ptr output);
   get_unchecked_mut : self → mut_raw_ptr t → result (mut_raw_ptr output);
   index : self → t → result output;
-  index_mut : self → t → result output;
-  index_mut_back : self → t → output → result t;
+  index_mut : self → t → result (output & (output -> result t));
 }
 
 // [core::slice::index::[T]::index]: forward function
@@ -643,14 +658,8 @@ let core_slice_index_RangeUsize_get (t : Type0) (i : core_ops_range_Range usize)
   admit () // TODO
 
 // [core::slice::index::Range::get_mut]: forward function
-let core_slice_index_RangeUsize_get_mut
-  (t : Type0) : core_ops_range_Range usize → slice t → result (option (slice t)) =
-  admit () // TODO
-
-// [core::slice::index::Range::get_mut]: backward function 0
-let core_slice_index_RangeUsize_get_mut_back
-  (t : Type0) :
-  core_ops_range_Range usize → slice t → option (slice t) → result (slice t) =
+let core_slice_index_RangeUsize_get_mut (t : Type0) :
+  core_ops_range_Range usize → slice t → result (option (slice t) & (option (slice t) -> result (slice t))) =
   admit () // TODO
 
 // [core::slice::index::Range::get_unchecked]: forward function
@@ -675,27 +684,16 @@ let core_slice_index_RangeUsize_index
   admit () // TODO
 
 // [core::slice::index::Range::index_mut]: forward function
-let core_slice_index_RangeUsize_index_mut
-  (t : Type0) : core_ops_range_Range usize → slice t → result (slice t) =
-  admit () // TODO
-
-// [core::slice::index::Range::index_mut]: backward function 0
-let core_slice_index_RangeUsize_index_mut_back
-  (t : Type0) : core_ops_range_Range usize → slice t → slice t → result (slice t) =
+let core_slice_index_RangeUsize_index_mut (t : Type0) :
+  core_ops_range_Range usize → slice t → result (slice t & (slice t -> result (slice t))) =
   admit () // TODO
 
 // [core::slice::index::[T]::index_mut]: forward function
 let core_slice_index_Slice_index_mut
   (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
-  slice t → idx → result inst.output =
+  slice t → idx → result (inst.output & (inst.output -> result (slice t))) =
   admit () // 
 
-// [core::slice::index::[T]::index_mut]: backward function 0
-let core_slice_index_Slice_index_mut_back
-  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
-  slice t → idx → inst.output → result (slice t) =
-  admit () // TODO
-
 // [core::array::[T; N]::index]: forward function
 let core_array_Array_index
   (t idx : Type0) (n : usize) (inst : core_ops_index_Index (slice t) idx)
@@ -705,13 +703,8 @@ let core_array_Array_index
 // [core::array::[T; N]::index_mut]: forward function
 let core_array_Array_index_mut
   (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
-  (a : array t n) (i : idx) : result inst.indexInst.output =
-  admit () // TODO
-
-// [core::array::[T; N]::index_mut]: backward function 0
-let core_array_Array_index_mut_back
-  (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
-  (a : array t n) (i : idx) (x : inst.indexInst.output) : result (array t n) =
+  (a : array t n) (i : idx) :
+  result (inst.indexInst.output & (inst.indexInst.output -> result (array t n))) =
   admit () // TODO
 
 // Trait implementation: [core::slice::index::private_slice_index::Range]
@@ -725,12 +718,10 @@ let core_slice_index_SliceIndexRangeUsizeSliceTInst (t : Type0) :
   output = slice t;
   get = core_slice_index_RangeUsize_get t;
   get_mut = core_slice_index_RangeUsize_get_mut t;
-  get_mut_back = core_slice_index_RangeUsize_get_mut_back t;
   get_unchecked = core_slice_index_RangeUsize_get_unchecked t;
   get_unchecked_mut = core_slice_index_RangeUsize_get_unchecked_mut t;
   index = core_slice_index_RangeUsize_index t;
   index_mut = core_slice_index_RangeUsize_index_mut t;
-  index_mut_back = core_slice_index_RangeUsize_index_mut_back t;
 }
 
 // Trait implementation: [core::slice::index::[T]]
@@ -747,7 +738,6 @@ let core_ops_index_IndexMutSliceTIInst (t idx : Type0)
   core_ops_index_IndexMut (slice t) idx = {
   indexInst = core_ops_index_IndexSliceTIInst t idx inst;
   index_mut = core_slice_index_Slice_index_mut t idx inst;
-  index_mut_back = core_slice_index_Slice_index_mut_back t idx inst;
 }
 
 // Trait implementation: [core::array::[T; N]]
@@ -764,7 +754,6 @@ let core_ops_index_IndexMutArrayIInst (t idx : Type0) (n : usize)
   core_ops_index_IndexMut (array t n) idx = {
   indexInst = core_ops_index_IndexArrayInst t idx n inst.indexInst;
   index_mut = core_array_Array_index_mut t idx n inst;
-  index_mut_back = core_array_Array_index_mut_back t idx n inst;
 }
 
 // [core::slice::index::usize::get]: forward function
@@ -773,13 +762,8 @@ let core_slice_index_usize_get
   admit () // TODO
 
 // [core::slice::index::usize::get_mut]: forward function
-let core_slice_index_usize_get_mut
-  (t : Type0) : usize → slice t → result (option t) =
-  admit () // TODO
-
-// [core::slice::index::usize::get_mut]: backward function 0
-let core_slice_index_usize_get_mut_back
-  (t : Type0) : usize → slice t → option t → result (slice t) =
+let core_slice_index_usize_get_mut (t : Type0) :
+  usize → slice t → result (option t & (option t -> result (slice t))) =
   admit () // TODO
 
 // [core::slice::index::usize::get_unchecked]: forward function
@@ -797,12 +781,8 @@ let core_slice_index_usize_index (t : Type0) : usize → slice t → result t =
   admit () // TODO
 
 // [core::slice::index::usize::index_mut]: forward function
-let core_slice_index_usize_index_mut (t : Type0) : usize → slice t → result t =
-  admit () // TODO
-
-// [core::slice::index::usize::index_mut]: backward function 0
-let core_slice_index_usize_index_mut_back
-  (t : Type0) : usize → slice t → t → result (slice t) =
+let core_slice_index_usize_index_mut (t : Type0) :
+  usize → slice t → result (t & (t -> result (slice t))) =
   admit () // TODO
 
 // Trait implementation: [core::slice::index::private_slice_index::usize]
@@ -816,12 +796,10 @@ let core_slice_index_SliceIndexUsizeSliceTInst (t : Type0) :
   output = t;
   get = core_slice_index_usize_get t;
   get_mut = core_slice_index_usize_get_mut t;
-  get_mut_back = core_slice_index_usize_get_mut_back t;
   get_unchecked = core_slice_index_usize_get_unchecked t;
   get_unchecked_mut = core_slice_index_usize_get_unchecked_mut t;
   index = core_slice_index_usize_index t;
   index_mut = core_slice_index_usize_index_mut t;
-  index_mut_back = core_slice_index_usize_index_mut_back t;
 }
 
 // [alloc::vec::Vec::index]: forward function
@@ -831,13 +809,8 @@ let alloc_vec_Vec_index (t idx : Type0) (inst : core_slice_index_SliceIndex idx
 
 // [alloc::vec::Vec::index_mut]: forward function
 let alloc_vec_Vec_index_mut (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
-  (self : alloc_vec_Vec t) (i : idx) : result inst.output =
-  admit () // TODO
-
-// [alloc::vec::Vec::index_mut]: backward function 0
-let alloc_vec_Vec_index_mut_back
-  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
-  (self : alloc_vec_Vec t) (i : idx) (x : inst.output) : result (alloc_vec_Vec t) =
+  (self : alloc_vec_Vec t) (i : idx) :
+  result (inst.output & (inst.output -> result (alloc_vec_Vec t))) =
   admit () // TODO
 
 // Trait implementation: [alloc::vec::Vec]
@@ -854,7 +827,6 @@ let alloc_vec_Vec_coreopsindexIndexMutInst (t idx : Type0)
   core_ops_index_IndexMut (alloc_vec_Vec t) idx = {
   indexInst = alloc_vec_Vec_coreopsindexIndexInst t idx inst;
   index_mut = alloc_vec_Vec_index_mut t idx inst;
-  index_mut_back = alloc_vec_Vec_index_mut_back t idx inst;
 }
 
 (*** Theorems *)
@@ -870,15 +842,7 @@ let alloc_vec_Vec_index_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
 let alloc_vec_Vec_index_mut_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
   Lemma (
     alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i ==
-      alloc_vec_Vec_index_usize v i)
+      alloc_vec_Vec_index_mut_usize v i)
   [SMTPat (alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i)]
   =
   admit()
-
-let alloc_vec_Vec_index_mut_back_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) :
-  Lemma (
-    alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x ==
-      alloc_vec_Vec_update_usize v i x)
-  [SMTPat (alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x)]
-  =
-  admit()
diff --git a/tests/fstar/hashmap/Hashmap.Funs.fst b/tests/fstar/hashmap/Hashmap.Funs.fst
index e6cd1411..9fc5d8a0 100644
--- a/tests/fstar/hashmap/Hashmap.Funs.fst
+++ b/tests/fstar/hashmap/Hashmap.Funs.fst
@@ -7,12 +7,12 @@ include Hashmap.Clauses
 
 #set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
 
-(** [hashmap::hash_key]: forward function
+(** [hashmap::hash_key]:
     Source: 'src/hashmap.rs', lines 27:0-27:32 *)
 let hash_key (k : usize) : result usize =
   Return k
 
-(** [hashmap::{hashmap::HashMap<T>}::allocate_slots]: loop 0: forward function
+(** [hashmap::{hashmap::HashMap<T>}::allocate_slots]: loop 0:
     Source: 'src/hashmap.rs', lines 50:4-56:5 *)
 let rec hashMap_allocate_slots_loop
   (t : Type0) (slots : alloc_vec_Vec (list_t t)) (n : usize) :
@@ -21,12 +21,12 @@ let rec hashMap_allocate_slots_loop
   =
   if n > 0
   then
-    let* slots0 = alloc_vec_Vec_push (list_t t) slots List_Nil in
-    let* n0 = usize_sub n 1 in
-    hashMap_allocate_slots_loop t slots0 n0
+    let* v = alloc_vec_Vec_push (list_t t) slots List_Nil in
+    let* n1 = usize_sub n 1 in
+    hashMap_allocate_slots_loop t v n1
   else Return slots
 
-(** [hashmap::{hashmap::HashMap<T>}::allocate_slots]: forward function
+(** [hashmap::{hashmap::HashMap<T>}::allocate_slots]:
     Source: 'src/hashmap.rs', lines 50:4-50:76 *)
 let hashMap_allocate_slots
   (t : Type0) (slots : alloc_vec_Vec (list_t t)) (n : usize) :
@@ -34,7 +34,7 @@ let hashMap_allocate_slots
   =
   hashMap_allocate_slots_loop t slots n
 
-(** [hashmap::{hashmap::HashMap<T>}::new_with_capacity]: forward function
+(** [hashmap::{hashmap::HashMap<T>}::new_with_capacity]:
     Source: 'src/hashmap.rs', lines 59:4-63:13 *)
 let hashMap_new_with_capacity
   (t : Type0) (capacity : usize) (max_load_dividend : usize)
@@ -44,97 +44,75 @@ let hashMap_new_with_capacity
   let v = alloc_vec_Vec_new (list_t t) in
   let* slots = hashMap_allocate_slots t v capacity in
   let* i = usize_mul capacity max_load_dividend in
-  let* i0 = usize_div i max_load_divisor in
+  let* i1 = usize_div i max_load_divisor in
   Return
     {
       num_entries = 0;
       max_load_factor = (max_load_dividend, max_load_divisor);
-      max_load = i0;
+      max_load = i1;
       slots = slots
     }
 
-(** [hashmap::{hashmap::HashMap<T>}::new]: forward function
+(** [hashmap::{hashmap::HashMap<T>}::new]:
     Source: 'src/hashmap.rs', lines 75:4-75:24 *)
 let hashMap_new (t : Type0) : result (hashMap_t t) =
   hashMap_new_with_capacity t 32 4 5
 
-(** [hashmap::{hashmap::HashMap<T>}::clear]: loop 0: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [hashmap::{hashmap::HashMap<T>}::clear]: loop 0:
     Source: 'src/hashmap.rs', lines 80:4-88:5 *)
 let rec hashMap_clear_loop
   (t : Type0) (slots : alloc_vec_Vec (list_t t)) (i : usize) :
   Tot (result (alloc_vec_Vec (list_t t)))
   (decreases (hashMap_clear_loop_decreases t slots i))
   =
-  let i0 = alloc_vec_Vec_len (list_t t) slots in
-  if i < i0
+  let i1 = alloc_vec_Vec_len (list_t t) slots in
+  if i < i1
   then
-    let* i1 = usize_add i 1 in
-    let* slots0 =
-      alloc_vec_Vec_index_mut_back (list_t t) usize
-        (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) slots i
-        List_Nil in
-    hashMap_clear_loop t slots0 i1
+    let* (_, index_mut_back) =
+      alloc_vec_Vec_index_mut (list_t t) usize
+        (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) slots i in
+    let* i2 = usize_add i 1 in
+    let* slots1 = index_mut_back List_Nil in
+    hashMap_clear_loop t slots1 i2
   else Return slots
 
-(** [hashmap::{hashmap::HashMap<T>}::clear]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [hashmap::{hashmap::HashMap<T>}::clear]:
     Source: 'src/hashmap.rs', lines 80:4-80:27 *)
 let hashMap_clear (t : Type0) (self : hashMap_t t) : result (hashMap_t t) =
-  let* v = hashMap_clear_loop t self.slots 0 in
-  Return { self with num_entries = 0; slots = v }
+  let* back = hashMap_clear_loop t self.slots 0 in
+  Return { self with num_entries = 0; slots = back }
 
-(** [hashmap::{hashmap::HashMap<T>}::len]: forward function
+(** [hashmap::{hashmap::HashMap<T>}::len]:
     Source: 'src/hashmap.rs', lines 90:4-90:30 *)
 let hashMap_len (t : Type0) (self : hashMap_t t) : result usize =
   Return self.num_entries
 
-(** [hashmap::{hashmap::HashMap<T>}::insert_in_list]: loop 0: forward function
+(** [hashmap::{hashmap::HashMap<T>}::insert_in_list]: loop 0:
     Source: 'src/hashmap.rs', lines 97:4-114:5 *)
 let rec hashMap_insert_in_list_loop
   (t : Type0) (key : usize) (value : t) (ls : list_t t) :
-  Tot (result bool)
+  Tot (result (bool & (list_t t)))
   (decreases (hashMap_insert_in_list_loop_decreases t key value ls))
   =
   begin match ls with
   | List_Cons ckey cvalue tl ->
     if ckey = key
-    then Return false
-    else hashMap_insert_in_list_loop t key value tl
-  | List_Nil -> Return true
+    then Return (false, List_Cons ckey value tl)
+    else
+      let* (b, back) = hashMap_insert_in_list_loop t key value tl in
+      Return (b, List_Cons ckey cvalue back)
+  | List_Nil -> let l = List_Nil in Return (true, List_Cons key value l)
   end
 
-(** [hashmap::{hashmap::HashMap<T>}::insert_in_list]: forward function
+(** [hashmap::{hashmap::HashMap<T>}::insert_in_list]:
     Source: 'src/hashmap.rs', lines 97:4-97:71 *)
 let hashMap_insert_in_list
-  (t : Type0) (key : usize) (value : t) (ls : list_t t) : result bool =
-  hashMap_insert_in_list_loop t key value ls
-
-(** [hashmap::{hashmap::HashMap<T>}::insert_in_list]: loop 0: backward function 0
-    Source: 'src/hashmap.rs', lines 97:4-114:5 *)
-let rec hashMap_insert_in_list_loop_back
   (t : Type0) (key : usize) (value : t) (ls : list_t t) :
-  Tot (result (list_t t))
-  (decreases (hashMap_insert_in_list_loop_decreases t key value ls))
+  result (bool & (list_t t))
   =
-  begin match ls with
-  | List_Cons ckey cvalue tl ->
-    if ckey = key
-    then Return (List_Cons ckey value tl)
-    else
-      let* tl0 = hashMap_insert_in_list_loop_back t key value tl in
-      Return (List_Cons ckey cvalue tl0)
-  | List_Nil -> let l = List_Nil in Return (List_Cons key value l)
-  end
-
-(** [hashmap::{hashmap::HashMap<T>}::insert_in_list]: backward function 0
-    Source: 'src/hashmap.rs', lines 97:4-97:71 *)
-let hashMap_insert_in_list_back
-  (t : Type0) (key : usize) (value : t) (ls : list_t t) : result (list_t t) =
-  hashMap_insert_in_list_loop_back t key value ls
+  hashMap_insert_in_list_loop t key value ls
 
-(** [hashmap::{hashmap::HashMap<T>}::insert_no_resize]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [hashmap::{hashmap::HashMap<T>}::insert_no_resize]:
     Source: 'src/hashmap.rs', lines 117:4-117:54 *)
 let hashMap_insert_no_resize
   (t : Type0) (self : hashMap_t t) (key : usize) (value : t) :
@@ -143,30 +121,19 @@ let hashMap_insert_no_resize
   let* hash = hash_key key in
   let i = alloc_vec_Vec_len (list_t t) self.slots in
   let* hash_mod = usize_rem hash i in
-  let* l =
+  let* (l, index_mut_back) =
     alloc_vec_Vec_index_mut (list_t t) usize
       (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
       hash_mod in
-  let* inserted = hashMap_insert_in_list t key value l in
+  let* (inserted, l1) = hashMap_insert_in_list t key value l in
   if inserted
   then
-    let* i0 = usize_add self.num_entries 1 in
-    let* l0 = hashMap_insert_in_list_back t key value l in
-    let* v =
-      alloc_vec_Vec_index_mut_back (list_t t) usize
-        (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
-        hash_mod l0 in
-    Return { self with num_entries = i0; slots = v }
-  else
-    let* l0 = hashMap_insert_in_list_back t key value l in
-    let* v =
-      alloc_vec_Vec_index_mut_back (list_t t) usize
-        (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
-        hash_mod l0 in
-    Return { self with slots = v }
-
-(** [hashmap::{hashmap::HashMap<T>}::move_elements_from_list]: loop 0: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+    let* i1 = usize_add self.num_entries 1 in
+    let* v = index_mut_back l1 in
+    Return { self with num_entries = i1; slots = v }
+  else let* v = index_mut_back l1 in Return { self with slots = v }
+
+(** [hashmap::{hashmap::HashMap<T>}::move_elements_from_list]: loop 0:
     Source: 'src/hashmap.rs', lines 183:4-196:5 *)
 let rec hashMap_move_elements_from_list_loop
   (t : Type0) (ntable : hashMap_t t) (ls : list_t t) :
@@ -175,20 +142,18 @@ let rec hashMap_move_elements_from_list_loop
   =
   begin match ls with
   | List_Cons k v tl ->
-    let* ntable0 = hashMap_insert_no_resize t ntable k v in
-    hashMap_move_elements_from_list_loop t ntable0 tl
+    let* hm = hashMap_insert_no_resize t ntable k v in
+    hashMap_move_elements_from_list_loop t hm tl
   | List_Nil -> Return ntable
   end
 
-(** [hashmap::{hashmap::HashMap<T>}::move_elements_from_list]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [hashmap::{hashmap::HashMap<T>}::move_elements_from_list]:
     Source: 'src/hashmap.rs', lines 183:4-183:72 *)
 let hashMap_move_elements_from_list
   (t : Type0) (ntable : hashMap_t t) (ls : list_t t) : result (hashMap_t t) =
   hashMap_move_elements_from_list_loop t ntable ls
 
-(** [hashmap::{hashmap::HashMap<T>}::move_elements]: loop 0: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [hashmap::{hashmap::HashMap<T>}::move_elements]: loop 0:
     Source: 'src/hashmap.rs', lines 171:4-180:5 *)
 let rec hashMap_move_elements_loop
   (t : Type0) (ntable : hashMap_t t) (slots : alloc_vec_Vec (list_t t))
@@ -196,64 +161,63 @@ let rec hashMap_move_elements_loop
   Tot (result ((hashMap_t t) & (alloc_vec_Vec (list_t t))))
   (decreases (hashMap_move_elements_loop_decreases t ntable slots i))
   =
-  let i0 = alloc_vec_Vec_len (list_t t) slots in
-  if i < i0
+  let i1 = alloc_vec_Vec_len (list_t t) slots in
+  if i < i1
   then
-    let* l =
+    let* (l, index_mut_back) =
       alloc_vec_Vec_index_mut (list_t t) usize
         (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) slots i in
-    let ls = core_mem_replace (list_t t) l List_Nil in
-    let* ntable0 = hashMap_move_elements_from_list t ntable ls in
-    let* i1 = usize_add i 1 in
-    let l0 = core_mem_replace_back (list_t t) l List_Nil in
-    let* slots0 =
-      alloc_vec_Vec_index_mut_back (list_t t) usize
-        (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) slots i l0 in
-    hashMap_move_elements_loop t ntable0 slots0 i1
+    let (ls, l1) = core_mem_replace (list_t t) l List_Nil in
+    let* hm = hashMap_move_elements_from_list t ntable ls in
+    let* i2 = usize_add i 1 in
+    let* slots1 = index_mut_back l1 in
+    let* back_'a = hashMap_move_elements_loop t hm slots1 i2 in
+    let (hm1, v) = back_'a in
+    Return (hm1, v)
   else Return (ntable, slots)
 
-(** [hashmap::{hashmap::HashMap<T>}::move_elements]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [hashmap::{hashmap::HashMap<T>}::move_elements]:
     Source: 'src/hashmap.rs', lines 171:4-171:95 *)
 let hashMap_move_elements
   (t : Type0) (ntable : hashMap_t t) (slots : alloc_vec_Vec (list_t t))
   (i : usize) :
   result ((hashMap_t t) & (alloc_vec_Vec (list_t t)))
   =
-  hashMap_move_elements_loop t ntable slots i
+  let* back_'a = hashMap_move_elements_loop t ntable slots i in
+  let (hm, v) = back_'a in
+  Return (hm, v)
 
-(** [hashmap::{hashmap::HashMap<T>}::try_resize]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [hashmap::{hashmap::HashMap<T>}::try_resize]:
     Source: 'src/hashmap.rs', lines 140:4-140:28 *)
 let hashMap_try_resize
   (t : Type0) (self : hashMap_t t) : result (hashMap_t t) =
   let* max_usize = scalar_cast U32 Usize core_u32_max in
   let capacity = alloc_vec_Vec_len (list_t t) self.slots in
   let* n1 = usize_div max_usize 2 in
-  let (i, i0) = self.max_load_factor in
-  let* i1 = usize_div n1 i in
-  if capacity <= i1
+  let (i, i1) = self.max_load_factor in
+  let* i2 = usize_div n1 i in
+  if capacity <= i2
   then
-    let* i2 = usize_mul capacity 2 in
-    let* ntable = hashMap_new_with_capacity t i2 i i0 in
-    let* (ntable0, _) = hashMap_move_elements t ntable self.slots 0 in
+    let* i3 = usize_mul capacity 2 in
+    let* ntable = hashMap_new_with_capacity t i3 i i1 in
+    let* p = hashMap_move_elements t ntable self.slots 0 in
+    let (ntable1, _) = p in
     Return
-      { ntable0 with num_entries = self.num_entries; max_load_factor = (i, i0)
+      { ntable1 with num_entries = self.num_entries; max_load_factor = (i, i1)
       }
-  else Return { self with max_load_factor = (i, i0) }
+  else Return { self with max_load_factor = (i, i1) }
 
-(** [hashmap::{hashmap::HashMap<T>}::insert]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [hashmap::{hashmap::HashMap<T>}::insert]:
     Source: 'src/hashmap.rs', lines 129:4-129:48 *)
 let hashMap_insert
   (t : Type0) (self : hashMap_t t) (key : usize) (value : t) :
   result (hashMap_t t)
   =
-  let* self0 = hashMap_insert_no_resize t self key value in
-  let* i = hashMap_len t self0 in
-  if i > self0.max_load then hashMap_try_resize t self0 else Return self0
+  let* hm = hashMap_insert_no_resize t self key value in
+  let* i = hashMap_len t hm in
+  if i > hm.max_load then hashMap_try_resize t hm else Return hm
 
-(** [hashmap::{hashmap::HashMap<T>}::contains_key_in_list]: loop 0: forward function
+(** [hashmap::{hashmap::HashMap<T>}::contains_key_in_list]: loop 0:
     Source: 'src/hashmap.rs', lines 206:4-219:5 *)
 let rec hashMap_contains_key_in_list_loop
   (t : Type0) (key : usize) (ls : list_t t) :
@@ -261,20 +225,20 @@ let rec hashMap_contains_key_in_list_loop
   (decreases (hashMap_contains_key_in_list_loop_decreases t key ls))
   =
   begin match ls with
-  | List_Cons ckey x tl ->
+  | List_Cons ckey _ tl ->
     if ckey = key
     then Return true
     else hashMap_contains_key_in_list_loop t key tl
   | List_Nil -> Return false
   end
 
-(** [hashmap::{hashmap::HashMap<T>}::contains_key_in_list]: forward function
+(** [hashmap::{hashmap::HashMap<T>}::contains_key_in_list]:
     Source: 'src/hashmap.rs', lines 206:4-206:68 *)
 let hashMap_contains_key_in_list
   (t : Type0) (key : usize) (ls : list_t t) : result bool =
   hashMap_contains_key_in_list_loop t key ls
 
-(** [hashmap::{hashmap::HashMap<T>}::contains_key]: forward function
+(** [hashmap::{hashmap::HashMap<T>}::contains_key]:
     Source: 'src/hashmap.rs', lines 199:4-199:49 *)
 let hashMap_contains_key
   (t : Type0) (self : hashMap_t t) (key : usize) : result bool =
@@ -287,7 +251,7 @@ let hashMap_contains_key
       hash_mod in
   hashMap_contains_key_in_list t key l
 
-(** [hashmap::{hashmap::HashMap<T>}::get_in_list]: loop 0: forward function
+(** [hashmap::{hashmap::HashMap<T>}::get_in_list]: loop 0:
     Source: 'src/hashmap.rs', lines 224:4-237:5 *)
 let rec hashMap_get_in_list_loop
   (t : Type0) (key : usize) (ls : list_t t) :
@@ -299,12 +263,12 @@ let rec hashMap_get_in_list_loop
   | List_Nil -> Fail Failure
   end
 
-(** [hashmap::{hashmap::HashMap<T>}::get_in_list]: forward function
+(** [hashmap::{hashmap::HashMap<T>}::get_in_list]:
     Source: 'src/hashmap.rs', lines 224:4-224:70 *)
 let hashMap_get_in_list (t : Type0) (key : usize) (ls : list_t t) : result t =
   hashMap_get_in_list_loop t key ls
 
-(** [hashmap::{hashmap::HashMap<T>}::get]: forward function
+(** [hashmap::{hashmap::HashMap<T>}::get]:
     Source: 'src/hashmap.rs', lines 239:4-239:55 *)
 let hashMap_get (t : Type0) (self : hashMap_t t) (key : usize) : result t =
   let* hash = hash_key key in
@@ -316,214 +280,147 @@ let hashMap_get (t : Type0) (self : hashMap_t t) (key : usize) : result t =
       hash_mod in
   hashMap_get_in_list t key l
 
-(** [hashmap::{hashmap::HashMap<T>}::get_mut_in_list]: loop 0: forward function
+(** [hashmap::{hashmap::HashMap<T>}::get_mut_in_list]: loop 0:
     Source: 'src/hashmap.rs', lines 245:4-254:5 *)
 let rec hashMap_get_mut_in_list_loop
   (t : Type0) (ls : list_t t) (key : usize) :
-  Tot (result t) (decreases (hashMap_get_mut_in_list_loop_decreases t ls key))
-  =
-  begin match ls with
-  | List_Cons ckey cvalue tl ->
-    if ckey = key then Return cvalue else hashMap_get_mut_in_list_loop t tl key
-  | List_Nil -> Fail Failure
-  end
-
-(** [hashmap::{hashmap::HashMap<T>}::get_mut_in_list]: forward function
-    Source: 'src/hashmap.rs', lines 245:4-245:86 *)
-let hashMap_get_mut_in_list
-  (t : Type0) (ls : list_t t) (key : usize) : result t =
-  hashMap_get_mut_in_list_loop t ls key
-
-(** [hashmap::{hashmap::HashMap<T>}::get_mut_in_list]: loop 0: backward function 0
-    Source: 'src/hashmap.rs', lines 245:4-254:5 *)
-let rec hashMap_get_mut_in_list_loop_back
-  (t : Type0) (ls : list_t t) (key : usize) (ret : t) :
-  Tot (result (list_t t))
+  Tot (result (t & (t -> result (list_t t))))
   (decreases (hashMap_get_mut_in_list_loop_decreases t ls key))
   =
   begin match ls with
   | List_Cons ckey cvalue tl ->
     if ckey = key
-    then Return (List_Cons ckey ret tl)
+    then
+      let back_'a = fun ret -> Return (List_Cons ckey ret tl) in
+      Return (cvalue, back_'a)
     else
-      let* tl0 = hashMap_get_mut_in_list_loop_back t tl key ret in
-      Return (List_Cons ckey cvalue tl0)
+      let* (x, back_'a) = hashMap_get_mut_in_list_loop t tl key in
+      let back_'a1 =
+        fun ret -> let* tl1 = back_'a ret in Return (List_Cons ckey cvalue tl1)
+        in
+      Return (x, back_'a1)
   | List_Nil -> Fail Failure
   end
 
-(** [hashmap::{hashmap::HashMap<T>}::get_mut_in_list]: backward function 0
+(** [hashmap::{hashmap::HashMap<T>}::get_mut_in_list]:
     Source: 'src/hashmap.rs', lines 245:4-245:86 *)
-let hashMap_get_mut_in_list_back
-  (t : Type0) (ls : list_t t) (key : usize) (ret : t) : result (list_t t) =
-  hashMap_get_mut_in_list_loop_back t ls key ret
-
-(** [hashmap::{hashmap::HashMap<T>}::get_mut]: forward function
-    Source: 'src/hashmap.rs', lines 257:4-257:67 *)
-let hashMap_get_mut (t : Type0) (self : hashMap_t t) (key : usize) : result t =
-  let* hash = hash_key key in
-  let i = alloc_vec_Vec_len (list_t t) self.slots in
-  let* hash_mod = usize_rem hash i in
-  let* l =
-    alloc_vec_Vec_index_mut (list_t t) usize
-      (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
-      hash_mod in
-  hashMap_get_mut_in_list t l key
+let hashMap_get_mut_in_list
+  (t : Type0) (ls : list_t t) (key : usize) :
+  result (t & (t -> result (list_t t)))
+  =
+  let* (x, back_'a) = hashMap_get_mut_in_list_loop t ls key in
+  let back_'a1 = fun ret -> back_'a ret in
+  Return (x, back_'a1)
 
-(** [hashmap::{hashmap::HashMap<T>}::get_mut]: backward function 0
+(** [hashmap::{hashmap::HashMap<T>}::get_mut]:
     Source: 'src/hashmap.rs', lines 257:4-257:67 *)
-let hashMap_get_mut_back
-  (t : Type0) (self : hashMap_t t) (key : usize) (ret : t) :
-  result (hashMap_t t)
+let hashMap_get_mut
+  (t : Type0) (self : hashMap_t t) (key : usize) :
+  result (t & (t -> result (hashMap_t t)))
   =
   let* hash = hash_key key in
   let i = alloc_vec_Vec_len (list_t t) self.slots in
   let* hash_mod = usize_rem hash i in
-  let* l =
+  let* (l, index_mut_back) =
     alloc_vec_Vec_index_mut (list_t t) usize
       (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
       hash_mod in
-  let* l0 = hashMap_get_mut_in_list_back t l key ret in
-  let* v =
-    alloc_vec_Vec_index_mut_back (list_t t) usize
-      (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
-      hash_mod l0 in
-  Return { self with slots = v }
-
-(** [hashmap::{hashmap::HashMap<T>}::remove_from_list]: loop 0: forward function
+  let* (x, get_mut_in_list_back) = hashMap_get_mut_in_list t l key in
+  let back_'a =
+    fun ret ->
+      let* l1 = get_mut_in_list_back ret in
+      let* v = index_mut_back l1 in
+      Return { self with slots = v } in
+  Return (x, back_'a)
+
+(** [hashmap::{hashmap::HashMap<T>}::remove_from_list]: loop 0:
     Source: 'src/hashmap.rs', lines 265:4-291:5 *)
 let rec hashMap_remove_from_list_loop
   (t : Type0) (key : usize) (ls : list_t t) :
-  Tot (result (option t))
+  Tot (result ((option t) & (list_t t)))
   (decreases (hashMap_remove_from_list_loop_decreases t key ls))
   =
   begin match ls with
   | List_Cons ckey x tl ->
     if ckey = key
     then
-      let mv_ls = core_mem_replace (list_t t) (List_Cons ckey x tl) List_Nil in
+      let (mv_ls, _) =
+        core_mem_replace (list_t t) (List_Cons ckey x tl) List_Nil in
       begin match mv_ls with
-      | List_Cons i cvalue tl0 -> Return (Some cvalue)
+      | List_Cons _ cvalue tl1 -> Return (Some cvalue, tl1)
       | List_Nil -> Fail Failure
       end
-    else hashMap_remove_from_list_loop t key tl
-  | List_Nil -> Return None
+    else
+      let* (o, back) = hashMap_remove_from_list_loop t key tl in
+      Return (o, List_Cons ckey x back)
+  | List_Nil -> Return (None, List_Nil)
   end
 
-(** [hashmap::{hashmap::HashMap<T>}::remove_from_list]: forward function
+(** [hashmap::{hashmap::HashMap<T>}::remove_from_list]:
     Source: 'src/hashmap.rs', lines 265:4-265:69 *)
 let hashMap_remove_from_list
-  (t : Type0) (key : usize) (ls : list_t t) : result (option t) =
-  hashMap_remove_from_list_loop t key ls
-
-(** [hashmap::{hashmap::HashMap<T>}::remove_from_list]: loop 0: backward function 1
-    Source: 'src/hashmap.rs', lines 265:4-291:5 *)
-let rec hashMap_remove_from_list_loop_back
   (t : Type0) (key : usize) (ls : list_t t) :
-  Tot (result (list_t t))
-  (decreases (hashMap_remove_from_list_loop_decreases t key ls))
+  result ((option t) & (list_t t))
   =
-  begin match ls with
-  | List_Cons ckey x tl ->
-    if ckey = key
-    then
-      let mv_ls = core_mem_replace (list_t t) (List_Cons ckey x tl) List_Nil in
-      begin match mv_ls with
-      | List_Cons i cvalue tl0 -> Return tl0
-      | List_Nil -> Fail Failure
-      end
-    else
-      let* tl0 = hashMap_remove_from_list_loop_back t key tl in
-      Return (List_Cons ckey x tl0)
-  | List_Nil -> Return List_Nil
-  end
-
-(** [hashmap::{hashmap::HashMap<T>}::remove_from_list]: backward function 1
-    Source: 'src/hashmap.rs', lines 265:4-265:69 *)
-let hashMap_remove_from_list_back
-  (t : Type0) (key : usize) (ls : list_t t) : result (list_t t) =
-  hashMap_remove_from_list_loop_back t key ls
+  hashMap_remove_from_list_loop t key ls
 
-(** [hashmap::{hashmap::HashMap<T>}::remove]: forward function
+(** [hashmap::{hashmap::HashMap<T>}::remove]:
     Source: 'src/hashmap.rs', lines 294:4-294:52 *)
 let hashMap_remove
-  (t : Type0) (self : hashMap_t t) (key : usize) : result (option t) =
-  let* hash = hash_key key in
-  let i = alloc_vec_Vec_len (list_t t) self.slots in
-  let* hash_mod = usize_rem hash i in
-  let* l =
-    alloc_vec_Vec_index_mut (list_t t) usize
-      (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
-      hash_mod in
-  let* x = hashMap_remove_from_list t key l in
-  begin match x with
-  | None -> Return None
-  | Some x0 -> let* _ = usize_sub self.num_entries 1 in Return (Some x0)
-  end
-
-(** [hashmap::{hashmap::HashMap<T>}::remove]: backward function 0
-    Source: 'src/hashmap.rs', lines 294:4-294:52 *)
-let hashMap_remove_back
-  (t : Type0) (self : hashMap_t t) (key : usize) : result (hashMap_t t) =
+  (t : Type0) (self : hashMap_t t) (key : usize) :
+  result ((option t) & (hashMap_t t))
+  =
   let* hash = hash_key key in
   let i = alloc_vec_Vec_len (list_t t) self.slots in
   let* hash_mod = usize_rem hash i in
-  let* l =
+  let* (l, index_mut_back) =
     alloc_vec_Vec_index_mut (list_t t) usize
       (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
       hash_mod in
-  let* x = hashMap_remove_from_list t key l in
+  let* (x, l1) = hashMap_remove_from_list t key l in
   begin match x with
   | None ->
-    let* l0 = hashMap_remove_from_list_back t key l in
-    let* v =
-      alloc_vec_Vec_index_mut_back (list_t t) usize
-        (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
-        hash_mod l0 in
-    Return { self with slots = v }
-  | Some x0 ->
-    let* i0 = usize_sub self.num_entries 1 in
-    let* l0 = hashMap_remove_from_list_back t key l in
-    let* v =
-      alloc_vec_Vec_index_mut_back (list_t t) usize
-        (core_slice_index_SliceIndexUsizeSliceTInst (list_t t)) self.slots
-        hash_mod l0 in
-    Return { self with num_entries = i0; slots = v }
+    let* v = index_mut_back l1 in Return (None, { self with slots = v })
+  | Some x1 ->
+    let* i1 = usize_sub self.num_entries 1 in
+    let* v = index_mut_back l1 in
+    Return (Some x1, { self with num_entries = i1; slots = v })
   end
 
-(** [hashmap::test1]: forward function
+(** [hashmap::test1]:
     Source: 'src/hashmap.rs', lines 315:0-315:10 *)
 let test1 : result unit =
   let* hm = hashMap_new u64 in
-  let* hm0 = hashMap_insert u64 hm 0 42 in
-  let* hm1 = hashMap_insert u64 hm0 128 18 in
-  let* hm2 = hashMap_insert u64 hm1 1024 138 in
-  let* hm3 = hashMap_insert u64 hm2 1056 256 in
-  let* i = hashMap_get u64 hm3 128 in
+  let* hm1 = hashMap_insert u64 hm 0 42 in
+  let* hm2 = hashMap_insert u64 hm1 128 18 in
+  let* hm3 = hashMap_insert u64 hm2 1024 138 in
+  let* hm4 = hashMap_insert u64 hm3 1056 256 in
+  let* i = hashMap_get u64 hm4 128 in
   if not (i = 18)
   then Fail Failure
   else
-    let* hm4 = hashMap_get_mut_back u64 hm3 1024 56 in
-    let* i0 = hashMap_get u64 hm4 1024 in
-    if not (i0 = 56)
+    let* (_, get_mut_back) = hashMap_get_mut u64 hm4 1024 in
+    let* hm5 = get_mut_back 56 in
+    let* i1 = hashMap_get u64 hm5 1024 in
+    if not (i1 = 56)
     then Fail Failure
     else
-      let* x = hashMap_remove u64 hm4 1024 in
+      let* (x, hm6) = hashMap_remove u64 hm5 1024 in
       begin match x with
       | None -> Fail Failure
-      | Some x0 ->
-        if not (x0 = 56)
+      | Some x1 ->
+        if not (x1 = 56)
         then Fail Failure
         else
-          let* hm5 = hashMap_remove_back u64 hm4 1024 in
-          let* i1 = hashMap_get u64 hm5 0 in
-          if not (i1 = 42)
+          let* i2 = hashMap_get u64 hm6 0 in
+          if not (i2 = 42)
           then Fail Failure
           else
-            let* i2 = hashMap_get u64 hm5 128 in
-            if not (i2 = 18)
+            let* i3 = hashMap_get u64 hm6 128 in
+            if not (i3 = 18)
             then Fail Failure
             else
-              let* i3 = hashMap_get u64 hm5 1056 in
-              if not (i3 = 256) then Fail Failure else Return ()
+              let* i4 = hashMap_get u64 hm6 1056 in
+              if not (i4 = 256) then Fail Failure else Return ()
       end
 
diff --git a/tests/fstar/hashmap/Primitives.fst b/tests/fstar/hashmap/Primitives.fst
index a3ffbde4..fca80829 100644
--- a/tests/fstar/hashmap/Primitives.fst
+++ b/tests/fstar/hashmap/Primitives.fst
@@ -55,8 +55,7 @@ type string = string
 let is_zero (n: nat) : bool = n = 0
 let decrease (n: nat{n > 0}) : nat = n - 1
 
-let core_mem_replace (a : Type0) (x : a) (y : a) : a = x
-let core_mem_replace_back (a : Type0) (x : a) (y : a) : a = y
+let core_mem_replace (a : Type0) (x : a) (y : a) : a & a = (x, x)
 
 // We don't really use raw pointers for now
 type mut_raw_ptr (t : Type0) = { v : t }
@@ -477,8 +476,7 @@ noeq type core_ops_index_Index (self idx : Type0) = {
 // Trait declaration: [core::ops::index::IndexMut]
 noeq type core_ops_index_IndexMut (self idx : Type0) = {
   indexInst : core_ops_index_Index self idx;
-  index_mut : self → idx → result indexInst.output;
-  index_mut_back : self → idx → indexInst.output → result self;
+  index_mut : self → idx → result (indexInst.output & (indexInst.output → result self));
 }
 
 // Trait declaration [core::ops::deref::Deref]
@@ -490,8 +488,7 @@ noeq type core_ops_deref_Deref (self : Type0) = {
 // Trait declaration [core::ops::deref::DerefMut]
 noeq type core_ops_deref_DerefMut (self : Type0) = {
   derefInst : core_ops_deref_Deref self;
-  deref_mut : self → result derefInst.target;
-  deref_mut_back : self → derefInst.target → result self;
+  deref_mut : self → result (derefInst.target & (derefInst.target → result self));
 }
 
 type core_ops_range_Range (a : Type0) = {
@@ -502,8 +499,8 @@ type core_ops_range_Range (a : Type0) = {
 (*** [alloc] *)
 
 let alloc_boxed_Box_deref (t : Type0) (x : t) : result t = Return x
-let alloc_boxed_Box_deref_mut (t : Type0) (x : t) : result t = Return x
-let alloc_boxed_Box_deref_mut_back (t : Type) (_ : t) (x : t) : result t = Return x
+let alloc_boxed_Box_deref_mut (t : Type0) (x : t) : result (t & (t -> result t)) =
+  Return (x, (fun x -> Return x))
 
 // Trait instance
 let alloc_boxed_Box_coreopsDerefInst (self : Type0) : core_ops_deref_Deref self = {
@@ -515,7 +512,6 @@ let alloc_boxed_Box_coreopsDerefInst (self : Type0) : core_ops_deref_Deref self
 let alloc_boxed_Box_coreopsDerefMutInst (self : Type0) : core_ops_deref_DerefMut self = {
   derefInst = alloc_boxed_Box_coreopsDerefInst self;
   deref_mut = alloc_boxed_Box_deref_mut self;
-  deref_mut_back = alloc_boxed_Box_deref_mut_back self;
 }
 
 (*** Array *)
@@ -535,10 +531,18 @@ let array_index_usize (a : Type0) (n : usize) (x : array a n) (i : usize) : resu
   if i < length x then Return (index x i)
   else Fail Failure
 
-let array_update_usize (a : Type0) (n : usize) (x : array a n) (i : usize) (nx : a) : result (array a n) =
+let array_update_usize (a : Type0) (n : usize) (x : array a n) (i : usize) (nx : a) :
+  result (array a n) =
   if i < length x then Return (list_update x i nx)
   else Fail Failure
 
+let array_index_mut_usize (a : Type0) (n : usize) (x : array a n) (i : usize) :
+  result (a & (a -> result (array a n))) =
+  match array_index_usize a n x i with
+  | Fail e -> Fail e
+  | Return v ->
+    Return (v, array_update_usize a n x i)
+
 (*** Slice *)
 type slice (a : Type0) = s:list a{length s <= usize_max}
 
@@ -552,6 +556,13 @@ let slice_update_usize (a : Type0) (x : slice a) (i : usize) (nx : a) : result (
   if i < length x then Return (list_update x i nx)
   else Fail Failure
 
+let slice_index_mut_usize (a : Type0) (s : slice a) (i : usize) :
+  result (a & (a -> result (slice a))) =
+  match slice_index_usize a s i with
+  | Fail e -> Fail e
+  | Return x ->
+    Return (x, slice_update_usize a s i)
+
 (*** Subslices *)
 
 let array_to_slice (a : Type0) (n : usize) (x : array a n) : result (slice a) = Return x
@@ -559,6 +570,10 @@ let array_from_slice (a : Type0) (n : usize) (x : array a n) (s : slice a) : res
   if length s = n then Return s
   else Fail Failure
 
+let array_to_slice_mut (a : Type0) (n : usize) (x : array a n) :
+  result (slice a & (slice a -> result (array a n))) =
+  Return (x, array_from_slice a n x)
+
 // TODO: finish the definitions below (there lacks [List.drop] and [List.take] in the standard library *)
 let array_subslice (a : Type0) (n : usize) (x : array a n) (r : core_ops_range_Range usize) : result (slice a) =
   admit()
@@ -588,8 +603,13 @@ let alloc_vec_Vec_index_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) : r
 let alloc_vec_Vec_update_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
   if i < length v then Return (list_update v i x) else Fail Failure
 
-// The **forward** function shouldn't be used
-let alloc_vec_Vec_push_fwd (a  : Type0) (v : alloc_vec_Vec a) (x : a) : unit = ()
+let alloc_vec_Vec_index_mut_usize (#a : Type0) (v: alloc_vec_Vec a) (i: usize) :
+  result (a & (a → result (alloc_vec_Vec a))) =
+  match alloc_vec_Vec_index_usize v i with
+  | Return x ->
+    Return (x, alloc_vec_Vec_update_usize v i)
+  | Fail e -> Fail e
+
 let alloc_vec_Vec_push (a  : Type0) (v : alloc_vec_Vec a) (x : a) :
   Pure (result (alloc_vec_Vec a))
   (requires True)
@@ -605,9 +625,6 @@ let alloc_vec_Vec_push (a  : Type0) (v : alloc_vec_Vec a) (x : a) :
     end
   else Fail Failure
 
-// The **forward** function shouldn't be used
-let alloc_vec_Vec_insert_fwd (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result unit =
-  if i < length v then Return () else Fail Failure
 let alloc_vec_Vec_insert (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
   if i < length v then Return (list_update v i x) else Fail Failure
 
@@ -619,13 +636,11 @@ noeq type core_slice_index_SliceIndex (self t : Type0) = {
   sealedInst : core_slice_index_private_slice_index_Sealed self;
   output : Type0;
   get : self → t → result (option output);
-  get_mut : self → t → result (option output);
-  get_mut_back : self → t → option output → result t;
+  get_mut : self → t → result (option output & (option output -> result t));
   get_unchecked : self → const_raw_ptr t → result (const_raw_ptr output);
   get_unchecked_mut : self → mut_raw_ptr t → result (mut_raw_ptr output);
   index : self → t → result output;
-  index_mut : self → t → result output;
-  index_mut_back : self → t → output → result t;
+  index_mut : self → t → result (output & (output -> result t));
 }
 
 // [core::slice::index::[T]::index]: forward function
@@ -643,14 +658,8 @@ let core_slice_index_RangeUsize_get (t : Type0) (i : core_ops_range_Range usize)
   admit () // TODO
 
 // [core::slice::index::Range::get_mut]: forward function
-let core_slice_index_RangeUsize_get_mut
-  (t : Type0) : core_ops_range_Range usize → slice t → result (option (slice t)) =
-  admit () // TODO
-
-// [core::slice::index::Range::get_mut]: backward function 0
-let core_slice_index_RangeUsize_get_mut_back
-  (t : Type0) :
-  core_ops_range_Range usize → slice t → option (slice t) → result (slice t) =
+let core_slice_index_RangeUsize_get_mut (t : Type0) :
+  core_ops_range_Range usize → slice t → result (option (slice t) & (option (slice t) -> result (slice t))) =
   admit () // TODO
 
 // [core::slice::index::Range::get_unchecked]: forward function
@@ -675,27 +684,16 @@ let core_slice_index_RangeUsize_index
   admit () // TODO
 
 // [core::slice::index::Range::index_mut]: forward function
-let core_slice_index_RangeUsize_index_mut
-  (t : Type0) : core_ops_range_Range usize → slice t → result (slice t) =
-  admit () // TODO
-
-// [core::slice::index::Range::index_mut]: backward function 0
-let core_slice_index_RangeUsize_index_mut_back
-  (t : Type0) : core_ops_range_Range usize → slice t → slice t → result (slice t) =
+let core_slice_index_RangeUsize_index_mut (t : Type0) :
+  core_ops_range_Range usize → slice t → result (slice t & (slice t -> result (slice t))) =
   admit () // TODO
 
 // [core::slice::index::[T]::index_mut]: forward function
 let core_slice_index_Slice_index_mut
   (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
-  slice t → idx → result inst.output =
+  slice t → idx → result (inst.output & (inst.output -> result (slice t))) =
   admit () // 
 
-// [core::slice::index::[T]::index_mut]: backward function 0
-let core_slice_index_Slice_index_mut_back
-  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
-  slice t → idx → inst.output → result (slice t) =
-  admit () // TODO
-
 // [core::array::[T; N]::index]: forward function
 let core_array_Array_index
   (t idx : Type0) (n : usize) (inst : core_ops_index_Index (slice t) idx)
@@ -705,13 +703,8 @@ let core_array_Array_index
 // [core::array::[T; N]::index_mut]: forward function
 let core_array_Array_index_mut
   (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
-  (a : array t n) (i : idx) : result inst.indexInst.output =
-  admit () // TODO
-
-// [core::array::[T; N]::index_mut]: backward function 0
-let core_array_Array_index_mut_back
-  (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
-  (a : array t n) (i : idx) (x : inst.indexInst.output) : result (array t n) =
+  (a : array t n) (i : idx) :
+  result (inst.indexInst.output & (inst.indexInst.output -> result (array t n))) =
   admit () // TODO
 
 // Trait implementation: [core::slice::index::private_slice_index::Range]
@@ -725,12 +718,10 @@ let core_slice_index_SliceIndexRangeUsizeSliceTInst (t : Type0) :
   output = slice t;
   get = core_slice_index_RangeUsize_get t;
   get_mut = core_slice_index_RangeUsize_get_mut t;
-  get_mut_back = core_slice_index_RangeUsize_get_mut_back t;
   get_unchecked = core_slice_index_RangeUsize_get_unchecked t;
   get_unchecked_mut = core_slice_index_RangeUsize_get_unchecked_mut t;
   index = core_slice_index_RangeUsize_index t;
   index_mut = core_slice_index_RangeUsize_index_mut t;
-  index_mut_back = core_slice_index_RangeUsize_index_mut_back t;
 }
 
 // Trait implementation: [core::slice::index::[T]]
@@ -747,7 +738,6 @@ let core_ops_index_IndexMutSliceTIInst (t idx : Type0)
   core_ops_index_IndexMut (slice t) idx = {
   indexInst = core_ops_index_IndexSliceTIInst t idx inst;
   index_mut = core_slice_index_Slice_index_mut t idx inst;
-  index_mut_back = core_slice_index_Slice_index_mut_back t idx inst;
 }
 
 // Trait implementation: [core::array::[T; N]]
@@ -764,7 +754,6 @@ let core_ops_index_IndexMutArrayIInst (t idx : Type0) (n : usize)
   core_ops_index_IndexMut (array t n) idx = {
   indexInst = core_ops_index_IndexArrayInst t idx n inst.indexInst;
   index_mut = core_array_Array_index_mut t idx n inst;
-  index_mut_back = core_array_Array_index_mut_back t idx n inst;
 }
 
 // [core::slice::index::usize::get]: forward function
@@ -773,13 +762,8 @@ let core_slice_index_usize_get
   admit () // TODO
 
 // [core::slice::index::usize::get_mut]: forward function
-let core_slice_index_usize_get_mut
-  (t : Type0) : usize → slice t → result (option t) =
-  admit () // TODO
-
-// [core::slice::index::usize::get_mut]: backward function 0
-let core_slice_index_usize_get_mut_back
-  (t : Type0) : usize → slice t → option t → result (slice t) =
+let core_slice_index_usize_get_mut (t : Type0) :
+  usize → slice t → result (option t & (option t -> result (slice t))) =
   admit () // TODO
 
 // [core::slice::index::usize::get_unchecked]: forward function
@@ -797,12 +781,8 @@ let core_slice_index_usize_index (t : Type0) : usize → slice t → result t =
   admit () // TODO
 
 // [core::slice::index::usize::index_mut]: forward function
-let core_slice_index_usize_index_mut (t : Type0) : usize → slice t → result t =
-  admit () // TODO
-
-// [core::slice::index::usize::index_mut]: backward function 0
-let core_slice_index_usize_index_mut_back
-  (t : Type0) : usize → slice t → t → result (slice t) =
+let core_slice_index_usize_index_mut (t : Type0) :
+  usize → slice t → result (t & (t -> result (slice t))) =
   admit () // TODO
 
 // Trait implementation: [core::slice::index::private_slice_index::usize]
@@ -816,12 +796,10 @@ let core_slice_index_SliceIndexUsizeSliceTInst (t : Type0) :
   output = t;
   get = core_slice_index_usize_get t;
   get_mut = core_slice_index_usize_get_mut t;
-  get_mut_back = core_slice_index_usize_get_mut_back t;
   get_unchecked = core_slice_index_usize_get_unchecked t;
   get_unchecked_mut = core_slice_index_usize_get_unchecked_mut t;
   index = core_slice_index_usize_index t;
   index_mut = core_slice_index_usize_index_mut t;
-  index_mut_back = core_slice_index_usize_index_mut_back t;
 }
 
 // [alloc::vec::Vec::index]: forward function
@@ -831,13 +809,8 @@ let alloc_vec_Vec_index (t idx : Type0) (inst : core_slice_index_SliceIndex idx
 
 // [alloc::vec::Vec::index_mut]: forward function
 let alloc_vec_Vec_index_mut (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
-  (self : alloc_vec_Vec t) (i : idx) : result inst.output =
-  admit () // TODO
-
-// [alloc::vec::Vec::index_mut]: backward function 0
-let alloc_vec_Vec_index_mut_back
-  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
-  (self : alloc_vec_Vec t) (i : idx) (x : inst.output) : result (alloc_vec_Vec t) =
+  (self : alloc_vec_Vec t) (i : idx) :
+  result (inst.output & (inst.output -> result (alloc_vec_Vec t))) =
   admit () // TODO
 
 // Trait implementation: [alloc::vec::Vec]
@@ -854,7 +827,6 @@ let alloc_vec_Vec_coreopsindexIndexMutInst (t idx : Type0)
   core_ops_index_IndexMut (alloc_vec_Vec t) idx = {
   indexInst = alloc_vec_Vec_coreopsindexIndexInst t idx inst;
   index_mut = alloc_vec_Vec_index_mut t idx inst;
-  index_mut_back = alloc_vec_Vec_index_mut_back t idx inst;
 }
 
 (*** Theorems *)
@@ -870,15 +842,7 @@ let alloc_vec_Vec_index_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
 let alloc_vec_Vec_index_mut_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
   Lemma (
     alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i ==
-      alloc_vec_Vec_index_usize v i)
+      alloc_vec_Vec_index_mut_usize v i)
   [SMTPat (alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i)]
   =
   admit()
-
-let alloc_vec_Vec_index_mut_back_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) :
-  Lemma (
-    alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x ==
-      alloc_vec_Vec_update_usize v i x)
-  [SMTPat (alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x)]
-  =
-  admit()
diff --git a/tests/fstar/hashmap_on_disk/HashmapMain.Funs.fst b/tests/fstar/hashmap_on_disk/HashmapMain.Funs.fst
index f2d09a38..3a042678 100644
--- a/tests/fstar/hashmap_on_disk/HashmapMain.Funs.fst
+++ b/tests/fstar/hashmap_on_disk/HashmapMain.Funs.fst
@@ -8,12 +8,12 @@ include HashmapMain.Clauses
 
 #set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
 
-(** [hashmap_main::hashmap::hash_key]: forward function
+(** [hashmap_main::hashmap::hash_key]:
     Source: 'src/hashmap.rs', lines 27:0-27:32 *)
 let hashmap_hash_key (k : usize) : result usize =
   Return k
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::allocate_slots]: loop 0: forward function
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::allocate_slots]: loop 0:
     Source: 'src/hashmap.rs', lines 50:4-56:5 *)
 let rec hashmap_HashMap_allocate_slots_loop
   (t : Type0) (slots : alloc_vec_Vec (hashmap_List_t t)) (n : usize) :
@@ -22,13 +22,12 @@ let rec hashmap_HashMap_allocate_slots_loop
   =
   if n > 0
   then
-    let* slots0 = alloc_vec_Vec_push (hashmap_List_t t) slots Hashmap_List_Nil
-      in
-    let* n0 = usize_sub n 1 in
-    hashmap_HashMap_allocate_slots_loop t slots0 n0
+    let* v = alloc_vec_Vec_push (hashmap_List_t t) slots Hashmap_List_Nil in
+    let* n1 = usize_sub n 1 in
+    hashmap_HashMap_allocate_slots_loop t v n1
   else Return slots
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::allocate_slots]: forward function
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::allocate_slots]:
     Source: 'src/hashmap.rs', lines 50:4-50:76 *)
 let hashmap_HashMap_allocate_slots
   (t : Type0) (slots : alloc_vec_Vec (hashmap_List_t t)) (n : usize) :
@@ -36,7 +35,7 @@ let hashmap_HashMap_allocate_slots
   =
   hashmap_HashMap_allocate_slots_loop t slots n
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::new_with_capacity]: forward function
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::new_with_capacity]:
     Source: 'src/hashmap.rs', lines 59:4-63:13 *)
 let hashmap_HashMap_new_with_capacity
   (t : Type0) (capacity : usize) (max_load_dividend : usize)
@@ -46,102 +45,79 @@ let hashmap_HashMap_new_with_capacity
   let v = alloc_vec_Vec_new (hashmap_List_t t) in
   let* slots = hashmap_HashMap_allocate_slots t v capacity in
   let* i = usize_mul capacity max_load_dividend in
-  let* i0 = usize_div i max_load_divisor in
+  let* i1 = usize_div i max_load_divisor in
   Return
     {
       num_entries = 0;
       max_load_factor = (max_load_dividend, max_load_divisor);
-      max_load = i0;
+      max_load = i1;
       slots = slots
     }
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::new]: forward function
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::new]:
     Source: 'src/hashmap.rs', lines 75:4-75:24 *)
 let hashmap_HashMap_new (t : Type0) : result (hashmap_HashMap_t t) =
   hashmap_HashMap_new_with_capacity t 32 4 5
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::clear]: loop 0: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::clear]: loop 0:
     Source: 'src/hashmap.rs', lines 80:4-88:5 *)
 let rec hashmap_HashMap_clear_loop
   (t : Type0) (slots : alloc_vec_Vec (hashmap_List_t t)) (i : usize) :
   Tot (result (alloc_vec_Vec (hashmap_List_t t)))
   (decreases (hashmap_HashMap_clear_loop_decreases t slots i))
   =
-  let i0 = alloc_vec_Vec_len (hashmap_List_t t) slots in
-  if i < i0
+  let i1 = alloc_vec_Vec_len (hashmap_List_t t) slots in
+  if i < i1
   then
-    let* i1 = usize_add i 1 in
-    let* slots0 =
-      alloc_vec_Vec_index_mut_back (hashmap_List_t t) usize
+    let* (_, index_mut_back) =
+      alloc_vec_Vec_index_mut (hashmap_List_t t) usize
         (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t)) slots i
-        Hashmap_List_Nil in
-    hashmap_HashMap_clear_loop t slots0 i1
+      in
+    let* i2 = usize_add i 1 in
+    let* slots1 = index_mut_back Hashmap_List_Nil in
+    hashmap_HashMap_clear_loop t slots1 i2
   else Return slots
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::clear]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::clear]:
     Source: 'src/hashmap.rs', lines 80:4-80:27 *)
 let hashmap_HashMap_clear
   (t : Type0) (self : hashmap_HashMap_t t) : result (hashmap_HashMap_t t) =
-  let* v = hashmap_HashMap_clear_loop t self.slots 0 in
-  Return { self with num_entries = 0; slots = v }
+  let* back = hashmap_HashMap_clear_loop t self.slots 0 in
+  Return { self with num_entries = 0; slots = back }
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::len]: forward function
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::len]:
     Source: 'src/hashmap.rs', lines 90:4-90:30 *)
 let hashmap_HashMap_len
   (t : Type0) (self : hashmap_HashMap_t t) : result usize =
   Return self.num_entries
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::insert_in_list]: loop 0: forward function
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::insert_in_list]: loop 0:
     Source: 'src/hashmap.rs', lines 97:4-114:5 *)
 let rec hashmap_HashMap_insert_in_list_loop
   (t : Type0) (key : usize) (value : t) (ls : hashmap_List_t t) :
-  Tot (result bool)
+  Tot (result (bool & (hashmap_List_t t)))
   (decreases (hashmap_HashMap_insert_in_list_loop_decreases t key value ls))
   =
   begin match ls with
   | Hashmap_List_Cons ckey cvalue tl ->
     if ckey = key
-    then Return false
-    else hashmap_HashMap_insert_in_list_loop t key value tl
-  | Hashmap_List_Nil -> Return true
-  end
-
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::insert_in_list]: forward function
-    Source: 'src/hashmap.rs', lines 97:4-97:71 *)
-let hashmap_HashMap_insert_in_list
-  (t : Type0) (key : usize) (value : t) (ls : hashmap_List_t t) : result bool =
-  hashmap_HashMap_insert_in_list_loop t key value ls
-
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::insert_in_list]: loop 0: backward function 0
-    Source: 'src/hashmap.rs', lines 97:4-114:5 *)
-let rec hashmap_HashMap_insert_in_list_loop_back
-  (t : Type0) (key : usize) (value : t) (ls : hashmap_List_t t) :
-  Tot (result (hashmap_List_t t))
-  (decreases (hashmap_HashMap_insert_in_list_loop_decreases t key value ls))
-  =
-  begin match ls with
-  | Hashmap_List_Cons ckey cvalue tl ->
-    if ckey = key
-    then Return (Hashmap_List_Cons ckey value tl)
+    then Return (false, Hashmap_List_Cons ckey value tl)
     else
-      let* tl0 = hashmap_HashMap_insert_in_list_loop_back t key value tl in
-      Return (Hashmap_List_Cons ckey cvalue tl0)
+      let* (b, back) = hashmap_HashMap_insert_in_list_loop t key value tl in
+      Return (b, Hashmap_List_Cons ckey cvalue back)
   | Hashmap_List_Nil ->
-    let l = Hashmap_List_Nil in Return (Hashmap_List_Cons key value l)
+    let l = Hashmap_List_Nil in Return (true, Hashmap_List_Cons key value l)
   end
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::insert_in_list]: backward function 0
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::insert_in_list]:
     Source: 'src/hashmap.rs', lines 97:4-97:71 *)
-let hashmap_HashMap_insert_in_list_back
+let hashmap_HashMap_insert_in_list
   (t : Type0) (key : usize) (value : t) (ls : hashmap_List_t t) :
-  result (hashmap_List_t t)
+  result (bool & (hashmap_List_t t))
   =
-  hashmap_HashMap_insert_in_list_loop_back t key value ls
+  hashmap_HashMap_insert_in_list_loop t key value ls
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::insert_no_resize]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::insert_no_resize]:
     Source: 'src/hashmap.rs', lines 117:4-117:54 *)
 let hashmap_HashMap_insert_no_resize
   (t : Type0) (self : hashmap_HashMap_t t) (key : usize) (value : t) :
@@ -150,30 +126,19 @@ let hashmap_HashMap_insert_no_resize
   let* hash = hashmap_hash_key key in
   let i = alloc_vec_Vec_len (hashmap_List_t t) self.slots in
   let* hash_mod = usize_rem hash i in
-  let* l =
+  let* (l, index_mut_back) =
     alloc_vec_Vec_index_mut (hashmap_List_t t) usize
       (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
       self.slots hash_mod in
-  let* inserted = hashmap_HashMap_insert_in_list t key value l in
+  let* (inserted, l1) = hashmap_HashMap_insert_in_list t key value l in
   if inserted
   then
-    let* i0 = usize_add self.num_entries 1 in
-    let* l0 = hashmap_HashMap_insert_in_list_back t key value l in
-    let* v =
-      alloc_vec_Vec_index_mut_back (hashmap_List_t t) usize
-        (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
-        self.slots hash_mod l0 in
-    Return { self with num_entries = i0; slots = v }
-  else
-    let* l0 = hashmap_HashMap_insert_in_list_back t key value l in
-    let* v =
-      alloc_vec_Vec_index_mut_back (hashmap_List_t t) usize
-        (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
-        self.slots hash_mod l0 in
-    Return { self with slots = v }
-
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::move_elements_from_list]: loop 0: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+    let* i1 = usize_add self.num_entries 1 in
+    let* v = index_mut_back l1 in
+    Return { self with num_entries = i1; slots = v }
+  else let* v = index_mut_back l1 in Return { self with slots = v }
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::move_elements_from_list]: loop 0:
     Source: 'src/hashmap.rs', lines 183:4-196:5 *)
 let rec hashmap_HashMap_move_elements_from_list_loop
   (t : Type0) (ntable : hashmap_HashMap_t t) (ls : hashmap_List_t t) :
@@ -183,13 +148,12 @@ let rec hashmap_HashMap_move_elements_from_list_loop
   =
   begin match ls with
   | Hashmap_List_Cons k v tl ->
-    let* ntable0 = hashmap_HashMap_insert_no_resize t ntable k v in
-    hashmap_HashMap_move_elements_from_list_loop t ntable0 tl
+    let* hm = hashmap_HashMap_insert_no_resize t ntable k v in
+    hashmap_HashMap_move_elements_from_list_loop t hm tl
   | Hashmap_List_Nil -> Return ntable
   end
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::move_elements_from_list]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::move_elements_from_list]:
     Source: 'src/hashmap.rs', lines 183:4-183:72 *)
 let hashmap_HashMap_move_elements_from_list
   (t : Type0) (ntable : hashmap_HashMap_t t) (ls : hashmap_List_t t) :
@@ -197,8 +161,7 @@ let hashmap_HashMap_move_elements_from_list
   =
   hashmap_HashMap_move_elements_from_list_loop t ntable ls
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::move_elements]: loop 0: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::move_elements]: loop 0:
     Source: 'src/hashmap.rs', lines 171:4-180:5 *)
 let rec hashmap_HashMap_move_elements_loop
   (t : Type0) (ntable : hashmap_HashMap_t t)
@@ -206,68 +169,64 @@ let rec hashmap_HashMap_move_elements_loop
   Tot (result ((hashmap_HashMap_t t) & (alloc_vec_Vec (hashmap_List_t t))))
   (decreases (hashmap_HashMap_move_elements_loop_decreases t ntable slots i))
   =
-  let i0 = alloc_vec_Vec_len (hashmap_List_t t) slots in
-  if i < i0
+  let i1 = alloc_vec_Vec_len (hashmap_List_t t) slots in
+  if i < i1
   then
-    let* l =
+    let* (l, index_mut_back) =
       alloc_vec_Vec_index_mut (hashmap_List_t t) usize
         (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t)) slots i
       in
-    let ls = core_mem_replace (hashmap_List_t t) l Hashmap_List_Nil in
-    let* ntable0 = hashmap_HashMap_move_elements_from_list t ntable ls in
-    let* i1 = usize_add i 1 in
-    let l0 = core_mem_replace_back (hashmap_List_t t) l Hashmap_List_Nil in
-    let* slots0 =
-      alloc_vec_Vec_index_mut_back (hashmap_List_t t) usize
-        (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t)) slots i
-        l0 in
-    hashmap_HashMap_move_elements_loop t ntable0 slots0 i1
+    let (ls, l1) = core_mem_replace (hashmap_List_t t) l Hashmap_List_Nil in
+    let* hm = hashmap_HashMap_move_elements_from_list t ntable ls in
+    let* i2 = usize_add i 1 in
+    let* slots1 = index_mut_back l1 in
+    let* back_'a = hashmap_HashMap_move_elements_loop t hm slots1 i2 in
+    let (hm1, v) = back_'a in
+    Return (hm1, v)
   else Return (ntable, slots)
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::move_elements]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::move_elements]:
     Source: 'src/hashmap.rs', lines 171:4-171:95 *)
 let hashmap_HashMap_move_elements
   (t : Type0) (ntable : hashmap_HashMap_t t)
   (slots : alloc_vec_Vec (hashmap_List_t t)) (i : usize) :
   result ((hashmap_HashMap_t t) & (alloc_vec_Vec (hashmap_List_t t)))
   =
-  hashmap_HashMap_move_elements_loop t ntable slots i
+  let* back_'a = hashmap_HashMap_move_elements_loop t ntable slots i in
+  let (hm, v) = back_'a in
+  Return (hm, v)
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::try_resize]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::try_resize]:
     Source: 'src/hashmap.rs', lines 140:4-140:28 *)
 let hashmap_HashMap_try_resize
   (t : Type0) (self : hashmap_HashMap_t t) : result (hashmap_HashMap_t t) =
   let* max_usize = scalar_cast U32 Usize core_u32_max in
   let capacity = alloc_vec_Vec_len (hashmap_List_t t) self.slots in
   let* n1 = usize_div max_usize 2 in
-  let (i, i0) = self.max_load_factor in
-  let* i1 = usize_div n1 i in
-  if capacity <= i1
+  let (i, i1) = self.max_load_factor in
+  let* i2 = usize_div n1 i in
+  if capacity <= i2
   then
-    let* i2 = usize_mul capacity 2 in
-    let* ntable = hashmap_HashMap_new_with_capacity t i2 i i0 in
-    let* (ntable0, _) = hashmap_HashMap_move_elements t ntable self.slots 0 in
+    let* i3 = usize_mul capacity 2 in
+    let* ntable = hashmap_HashMap_new_with_capacity t i3 i i1 in
+    let* p = hashmap_HashMap_move_elements t ntable self.slots 0 in
+    let (ntable1, _) = p in
     Return
-      { ntable0 with num_entries = self.num_entries; max_load_factor = (i, i0)
+      { ntable1 with num_entries = self.num_entries; max_load_factor = (i, i1)
       }
-  else Return { self with max_load_factor = (i, i0) }
+  else Return { self with max_load_factor = (i, i1) }
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::insert]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::insert]:
     Source: 'src/hashmap.rs', lines 129:4-129:48 *)
 let hashmap_HashMap_insert
   (t : Type0) (self : hashmap_HashMap_t t) (key : usize) (value : t) :
   result (hashmap_HashMap_t t)
   =
-  let* self0 = hashmap_HashMap_insert_no_resize t self key value in
-  let* i = hashmap_HashMap_len t self0 in
-  if i > self0.max_load
-  then hashmap_HashMap_try_resize t self0
-  else Return self0
+  let* hm = hashmap_HashMap_insert_no_resize t self key value in
+  let* i = hashmap_HashMap_len t hm in
+  if i > hm.max_load then hashmap_HashMap_try_resize t hm else Return hm
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::contains_key_in_list]: loop 0: forward function
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::contains_key_in_list]: loop 0:
     Source: 'src/hashmap.rs', lines 206:4-219:5 *)
 let rec hashmap_HashMap_contains_key_in_list_loop
   (t : Type0) (key : usize) (ls : hashmap_List_t t) :
@@ -275,20 +234,20 @@ let rec hashmap_HashMap_contains_key_in_list_loop
   (decreases (hashmap_HashMap_contains_key_in_list_loop_decreases t key ls))
   =
   begin match ls with
-  | Hashmap_List_Cons ckey x tl ->
+  | Hashmap_List_Cons ckey _ tl ->
     if ckey = key
     then Return true
     else hashmap_HashMap_contains_key_in_list_loop t key tl
   | Hashmap_List_Nil -> Return false
   end
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::contains_key_in_list]: forward function
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::contains_key_in_list]:
     Source: 'src/hashmap.rs', lines 206:4-206:68 *)
 let hashmap_HashMap_contains_key_in_list
   (t : Type0) (key : usize) (ls : hashmap_List_t t) : result bool =
   hashmap_HashMap_contains_key_in_list_loop t key ls
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::contains_key]: forward function
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::contains_key]:
     Source: 'src/hashmap.rs', lines 199:4-199:49 *)
 let hashmap_HashMap_contains_key
   (t : Type0) (self : hashmap_HashMap_t t) (key : usize) : result bool =
@@ -301,7 +260,7 @@ let hashmap_HashMap_contains_key
       self.slots hash_mod in
   hashmap_HashMap_contains_key_in_list t key l
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_in_list]: loop 0: forward function
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_in_list]: loop 0:
     Source: 'src/hashmap.rs', lines 224:4-237:5 *)
 let rec hashmap_HashMap_get_in_list_loop
   (t : Type0) (key : usize) (ls : hashmap_List_t t) :
@@ -316,13 +275,13 @@ let rec hashmap_HashMap_get_in_list_loop
   | Hashmap_List_Nil -> Fail Failure
   end
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_in_list]: forward function
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_in_list]:
     Source: 'src/hashmap.rs', lines 224:4-224:70 *)
 let hashmap_HashMap_get_in_list
   (t : Type0) (key : usize) (ls : hashmap_List_t t) : result t =
   hashmap_HashMap_get_in_list_loop t key ls
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get]: forward function
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get]:
     Source: 'src/hashmap.rs', lines 239:4-239:55 *)
 let hashmap_HashMap_get
   (t : Type0) (self : hashmap_HashMap_t t) (key : usize) : result t =
@@ -335,241 +294,162 @@ let hashmap_HashMap_get
       self.slots hash_mod in
   hashmap_HashMap_get_in_list t key l
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_mut_in_list]: loop 0: forward function
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_mut_in_list]: loop 0:
     Source: 'src/hashmap.rs', lines 245:4-254:5 *)
 let rec hashmap_HashMap_get_mut_in_list_loop
   (t : Type0) (ls : hashmap_List_t t) (key : usize) :
-  Tot (result t)
-  (decreases (hashmap_HashMap_get_mut_in_list_loop_decreases t ls key))
-  =
-  begin match ls with
-  | Hashmap_List_Cons ckey cvalue tl ->
-    if ckey = key
-    then Return cvalue
-    else hashmap_HashMap_get_mut_in_list_loop t tl key
-  | Hashmap_List_Nil -> Fail Failure
-  end
-
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_mut_in_list]: forward function
-    Source: 'src/hashmap.rs', lines 245:4-245:86 *)
-let hashmap_HashMap_get_mut_in_list
-  (t : Type0) (ls : hashmap_List_t t) (key : usize) : result t =
-  hashmap_HashMap_get_mut_in_list_loop t ls key
-
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_mut_in_list]: loop 0: backward function 0
-    Source: 'src/hashmap.rs', lines 245:4-254:5 *)
-let rec hashmap_HashMap_get_mut_in_list_loop_back
-  (t : Type0) (ls : hashmap_List_t t) (key : usize) (ret : t) :
-  Tot (result (hashmap_List_t t))
+  Tot (result (t & (t -> result (hashmap_List_t t))))
   (decreases (hashmap_HashMap_get_mut_in_list_loop_decreases t ls key))
   =
   begin match ls with
   | Hashmap_List_Cons ckey cvalue tl ->
     if ckey = key
-    then Return (Hashmap_List_Cons ckey ret tl)
+    then
+      let back_'a = fun ret -> Return (Hashmap_List_Cons ckey ret tl) in
+      Return (cvalue, back_'a)
     else
-      let* tl0 = hashmap_HashMap_get_mut_in_list_loop_back t tl key ret in
-      Return (Hashmap_List_Cons ckey cvalue tl0)
+      let* (x, back_'a) = hashmap_HashMap_get_mut_in_list_loop t tl key in
+      let back_'a1 =
+        fun ret ->
+          let* tl1 = back_'a ret in Return (Hashmap_List_Cons ckey cvalue tl1)
+        in
+      Return (x, back_'a1)
   | Hashmap_List_Nil -> Fail Failure
   end
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_mut_in_list]: backward function 0
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_mut_in_list]:
     Source: 'src/hashmap.rs', lines 245:4-245:86 *)
-let hashmap_HashMap_get_mut_in_list_back
-  (t : Type0) (ls : hashmap_List_t t) (key : usize) (ret : t) :
-  result (hashmap_List_t t)
+let hashmap_HashMap_get_mut_in_list
+  (t : Type0) (ls : hashmap_List_t t) (key : usize) :
+  result (t & (t -> result (hashmap_List_t t)))
   =
-  hashmap_HashMap_get_mut_in_list_loop_back t ls key ret
+  let* (x, back_'a) = hashmap_HashMap_get_mut_in_list_loop t ls key in
+  let back_'a1 = fun ret -> back_'a ret in
+  Return (x, back_'a1)
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_mut]: forward function
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_mut]:
     Source: 'src/hashmap.rs', lines 257:4-257:67 *)
 let hashmap_HashMap_get_mut
-  (t : Type0) (self : hashmap_HashMap_t t) (key : usize) : result t =
-  let* hash = hashmap_hash_key key in
-  let i = alloc_vec_Vec_len (hashmap_List_t t) self.slots in
-  let* hash_mod = usize_rem hash i in
-  let* l =
-    alloc_vec_Vec_index_mut (hashmap_List_t t) usize
-      (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
-      self.slots hash_mod in
-  hashmap_HashMap_get_mut_in_list t l key
-
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::get_mut]: backward function 0
-    Source: 'src/hashmap.rs', lines 257:4-257:67 *)
-let hashmap_HashMap_get_mut_back
-  (t : Type0) (self : hashmap_HashMap_t t) (key : usize) (ret : t) :
-  result (hashmap_HashMap_t t)
+  (t : Type0) (self : hashmap_HashMap_t t) (key : usize) :
+  result (t & (t -> result (hashmap_HashMap_t t)))
   =
   let* hash = hashmap_hash_key key in
   let i = alloc_vec_Vec_len (hashmap_List_t t) self.slots in
   let* hash_mod = usize_rem hash i in
-  let* l =
+  let* (l, index_mut_back) =
     alloc_vec_Vec_index_mut (hashmap_List_t t) usize
       (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
       self.slots hash_mod in
-  let* l0 = hashmap_HashMap_get_mut_in_list_back t l key ret in
-  let* v =
-    alloc_vec_Vec_index_mut_back (hashmap_List_t t) usize
-      (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
-      self.slots hash_mod l0 in
-  Return { self with slots = v }
-
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::remove_from_list]: loop 0: forward function
+  let* (x, get_mut_in_list_back) = hashmap_HashMap_get_mut_in_list t l key in
+  let back_'a =
+    fun ret ->
+      let* l1 = get_mut_in_list_back ret in
+      let* v = index_mut_back l1 in
+      Return { self with slots = v } in
+  Return (x, back_'a)
+
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::remove_from_list]: loop 0:
     Source: 'src/hashmap.rs', lines 265:4-291:5 *)
 let rec hashmap_HashMap_remove_from_list_loop
   (t : Type0) (key : usize) (ls : hashmap_List_t t) :
-  Tot (result (option t))
+  Tot (result ((option t) & (hashmap_List_t t)))
   (decreases (hashmap_HashMap_remove_from_list_loop_decreases t key ls))
   =
   begin match ls with
   | Hashmap_List_Cons ckey x tl ->
     if ckey = key
     then
-      let mv_ls =
+      let (mv_ls, _) =
         core_mem_replace (hashmap_List_t t) (Hashmap_List_Cons ckey x tl)
           Hashmap_List_Nil in
       begin match mv_ls with
-      | Hashmap_List_Cons i cvalue tl0 -> Return (Some cvalue)
-      | Hashmap_List_Nil -> Fail Failure
-      end
-    else hashmap_HashMap_remove_from_list_loop t key tl
-  | Hashmap_List_Nil -> Return None
-  end
-
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::remove_from_list]: forward function
-    Source: 'src/hashmap.rs', lines 265:4-265:69 *)
-let hashmap_HashMap_remove_from_list
-  (t : Type0) (key : usize) (ls : hashmap_List_t t) : result (option t) =
-  hashmap_HashMap_remove_from_list_loop t key ls
-
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::remove_from_list]: loop 0: backward function 1
-    Source: 'src/hashmap.rs', lines 265:4-291:5 *)
-let rec hashmap_HashMap_remove_from_list_loop_back
-  (t : Type0) (key : usize) (ls : hashmap_List_t t) :
-  Tot (result (hashmap_List_t t))
-  (decreases (hashmap_HashMap_remove_from_list_loop_decreases t key ls))
-  =
-  begin match ls with
-  | Hashmap_List_Cons ckey x tl ->
-    if ckey = key
-    then
-      let mv_ls =
-        core_mem_replace (hashmap_List_t t) (Hashmap_List_Cons ckey x tl)
-          Hashmap_List_Nil in
-      begin match mv_ls with
-      | Hashmap_List_Cons i cvalue tl0 -> Return tl0
+      | Hashmap_List_Cons _ cvalue tl1 -> Return (Some cvalue, tl1)
       | Hashmap_List_Nil -> Fail Failure
       end
     else
-      let* tl0 = hashmap_HashMap_remove_from_list_loop_back t key tl in
-      Return (Hashmap_List_Cons ckey x tl0)
-  | Hashmap_List_Nil -> Return Hashmap_List_Nil
+      let* (o, back) = hashmap_HashMap_remove_from_list_loop t key tl in
+      Return (o, Hashmap_List_Cons ckey x back)
+  | Hashmap_List_Nil -> Return (None, Hashmap_List_Nil)
   end
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::remove_from_list]: backward function 1
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::remove_from_list]:
     Source: 'src/hashmap.rs', lines 265:4-265:69 *)
-let hashmap_HashMap_remove_from_list_back
+let hashmap_HashMap_remove_from_list
   (t : Type0) (key : usize) (ls : hashmap_List_t t) :
-  result (hashmap_List_t t)
+  result ((option t) & (hashmap_List_t t))
   =
-  hashmap_HashMap_remove_from_list_loop_back t key ls
+  hashmap_HashMap_remove_from_list_loop t key ls
 
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::remove]: forward function
+(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::remove]:
     Source: 'src/hashmap.rs', lines 294:4-294:52 *)
 let hashmap_HashMap_remove
-  (t : Type0) (self : hashmap_HashMap_t t) (key : usize) : result (option t) =
-  let* hash = hashmap_hash_key key in
-  let i = alloc_vec_Vec_len (hashmap_List_t t) self.slots in
-  let* hash_mod = usize_rem hash i in
-  let* l =
-    alloc_vec_Vec_index_mut (hashmap_List_t t) usize
-      (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
-      self.slots hash_mod in
-  let* x = hashmap_HashMap_remove_from_list t key l in
-  begin match x with
-  | None -> Return None
-  | Some x0 -> let* _ = usize_sub self.num_entries 1 in Return (Some x0)
-  end
-
-(** [hashmap_main::hashmap::{hashmap_main::hashmap::HashMap<T>}::remove]: backward function 0
-    Source: 'src/hashmap.rs', lines 294:4-294:52 *)
-let hashmap_HashMap_remove_back
   (t : Type0) (self : hashmap_HashMap_t t) (key : usize) :
-  result (hashmap_HashMap_t t)
+  result ((option t) & (hashmap_HashMap_t t))
   =
   let* hash = hashmap_hash_key key in
   let i = alloc_vec_Vec_len (hashmap_List_t t) self.slots in
   let* hash_mod = usize_rem hash i in
-  let* l =
+  let* (l, index_mut_back) =
     alloc_vec_Vec_index_mut (hashmap_List_t t) usize
       (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
       self.slots hash_mod in
-  let* x = hashmap_HashMap_remove_from_list t key l in
+  let* (x, l1) = hashmap_HashMap_remove_from_list t key l in
   begin match x with
   | None ->
-    let* l0 = hashmap_HashMap_remove_from_list_back t key l in
-    let* v =
-      alloc_vec_Vec_index_mut_back (hashmap_List_t t) usize
-        (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
-        self.slots hash_mod l0 in
-    Return { self with slots = v }
-  | Some x0 ->
-    let* i0 = usize_sub self.num_entries 1 in
-    let* l0 = hashmap_HashMap_remove_from_list_back t key l in
-    let* v =
-      alloc_vec_Vec_index_mut_back (hashmap_List_t t) usize
-        (core_slice_index_SliceIndexUsizeSliceTInst (hashmap_List_t t))
-        self.slots hash_mod l0 in
-    Return { self with num_entries = i0; slots = v }
+    let* v = index_mut_back l1 in Return (None, { self with slots = v })
+  | Some x1 ->
+    let* i1 = usize_sub self.num_entries 1 in
+    let* v = index_mut_back l1 in
+    Return (Some x1, { self with num_entries = i1; slots = v })
   end
 
-(** [hashmap_main::hashmap::test1]: forward function
+(** [hashmap_main::hashmap::test1]:
     Source: 'src/hashmap.rs', lines 315:0-315:10 *)
 let hashmap_test1 : result unit =
   let* hm = hashmap_HashMap_new u64 in
-  let* hm0 = hashmap_HashMap_insert u64 hm 0 42 in
-  let* hm1 = hashmap_HashMap_insert u64 hm0 128 18 in
-  let* hm2 = hashmap_HashMap_insert u64 hm1 1024 138 in
-  let* hm3 = hashmap_HashMap_insert u64 hm2 1056 256 in
-  let* i = hashmap_HashMap_get u64 hm3 128 in
+  let* hm1 = hashmap_HashMap_insert u64 hm 0 42 in
+  let* hm2 = hashmap_HashMap_insert u64 hm1 128 18 in
+  let* hm3 = hashmap_HashMap_insert u64 hm2 1024 138 in
+  let* hm4 = hashmap_HashMap_insert u64 hm3 1056 256 in
+  let* i = hashmap_HashMap_get u64 hm4 128 in
   if not (i = 18)
   then Fail Failure
   else
-    let* hm4 = hashmap_HashMap_get_mut_back u64 hm3 1024 56 in
-    let* i0 = hashmap_HashMap_get u64 hm4 1024 in
-    if not (i0 = 56)
+    let* (_, get_mut_back) = hashmap_HashMap_get_mut u64 hm4 1024 in
+    let* hm5 = get_mut_back 56 in
+    let* i1 = hashmap_HashMap_get u64 hm5 1024 in
+    if not (i1 = 56)
     then Fail Failure
     else
-      let* x = hashmap_HashMap_remove u64 hm4 1024 in
+      let* (x, hm6) = hashmap_HashMap_remove u64 hm5 1024 in
       begin match x with
       | None -> Fail Failure
-      | Some x0 ->
-        if not (x0 = 56)
+      | Some x1 ->
+        if not (x1 = 56)
         then Fail Failure
         else
-          let* hm5 = hashmap_HashMap_remove_back u64 hm4 1024 in
-          let* i1 = hashmap_HashMap_get u64 hm5 0 in
-          if not (i1 = 42)
+          let* i2 = hashmap_HashMap_get u64 hm6 0 in
+          if not (i2 = 42)
           then Fail Failure
           else
-            let* i2 = hashmap_HashMap_get u64 hm5 128 in
-            if not (i2 = 18)
+            let* i3 = hashmap_HashMap_get u64 hm6 128 in
+            if not (i3 = 18)
             then Fail Failure
             else
-              let* i3 = hashmap_HashMap_get u64 hm5 1056 in
-              if not (i3 = 256) then Fail Failure else Return ()
+              let* i4 = hashmap_HashMap_get u64 hm6 1056 in
+              if not (i4 = 256) then Fail Failure else Return ()
       end
 
-(** [hashmap_main::insert_on_disk]: forward function
+(** [hashmap_main::insert_on_disk]:
     Source: 'src/hashmap_main.rs', lines 7:0-7:43 *)
 let insert_on_disk
   (key : usize) (value : u64) (st : state) : result (state & unit) =
-  let* (st0, hm) = hashmap_utils_deserialize st in
-  let* hm0 = hashmap_HashMap_insert u64 hm key value in
-  let* (st1, _) = hashmap_utils_serialize hm0 st0 in
-  Return (st1, ())
+  let* (st1, hm) = hashmap_utils_deserialize st in
+  let* hm1 = hashmap_HashMap_insert u64 hm key value in
+  let* (st2, _) = hashmap_utils_serialize hm1 st1 in
+  Return (st2, ())
 
-(** [hashmap_main::main]: forward function
+(** [hashmap_main::main]:
     Source: 'src/hashmap_main.rs', lines 16:0-16:13 *)
 let main : result unit =
   Return ()
diff --git a/tests/fstar/hashmap_on_disk/HashmapMain.FunsExternal.fsti b/tests/fstar/hashmap_on_disk/HashmapMain.FunsExternal.fsti
index b00bbcde..50a6509f 100644
--- a/tests/fstar/hashmap_on_disk/HashmapMain.FunsExternal.fsti
+++ b/tests/fstar/hashmap_on_disk/HashmapMain.FunsExternal.fsti
@@ -6,12 +6,12 @@ include HashmapMain.Types
 
 #set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
 
-(** [hashmap_main::hashmap_utils::deserialize]: forward function
+(** [hashmap_main::hashmap_utils::deserialize]:
     Source: 'src/hashmap_utils.rs', lines 10:0-10:43 *)
 val hashmap_utils_deserialize
   : state -> result (state & (hashmap_HashMap_t u64))
 
-(** [hashmap_main::hashmap_utils::serialize]: forward function
+(** [hashmap_main::hashmap_utils::serialize]:
     Source: 'src/hashmap_utils.rs', lines 5:0-5:42 *)
 val hashmap_utils_serialize
   : hashmap_HashMap_t u64 -> state -> result (state & unit)
diff --git a/tests/fstar/hashmap_on_disk/Primitives.fst b/tests/fstar/hashmap_on_disk/Primitives.fst
index a3ffbde4..fca80829 100644
--- a/tests/fstar/hashmap_on_disk/Primitives.fst
+++ b/tests/fstar/hashmap_on_disk/Primitives.fst
@@ -55,8 +55,7 @@ type string = string
 let is_zero (n: nat) : bool = n = 0
 let decrease (n: nat{n > 0}) : nat = n - 1
 
-let core_mem_replace (a : Type0) (x : a) (y : a) : a = x
-let core_mem_replace_back (a : Type0) (x : a) (y : a) : a = y
+let core_mem_replace (a : Type0) (x : a) (y : a) : a & a = (x, x)
 
 // We don't really use raw pointers for now
 type mut_raw_ptr (t : Type0) = { v : t }
@@ -477,8 +476,7 @@ noeq type core_ops_index_Index (self idx : Type0) = {
 // Trait declaration: [core::ops::index::IndexMut]
 noeq type core_ops_index_IndexMut (self idx : Type0) = {
   indexInst : core_ops_index_Index self idx;
-  index_mut : self → idx → result indexInst.output;
-  index_mut_back : self → idx → indexInst.output → result self;
+  index_mut : self → idx → result (indexInst.output & (indexInst.output → result self));
 }
 
 // Trait declaration [core::ops::deref::Deref]
@@ -490,8 +488,7 @@ noeq type core_ops_deref_Deref (self : Type0) = {
 // Trait declaration [core::ops::deref::DerefMut]
 noeq type core_ops_deref_DerefMut (self : Type0) = {
   derefInst : core_ops_deref_Deref self;
-  deref_mut : self → result derefInst.target;
-  deref_mut_back : self → derefInst.target → result self;
+  deref_mut : self → result (derefInst.target & (derefInst.target → result self));
 }
 
 type core_ops_range_Range (a : Type0) = {
@@ -502,8 +499,8 @@ type core_ops_range_Range (a : Type0) = {
 (*** [alloc] *)
 
 let alloc_boxed_Box_deref (t : Type0) (x : t) : result t = Return x
-let alloc_boxed_Box_deref_mut (t : Type0) (x : t) : result t = Return x
-let alloc_boxed_Box_deref_mut_back (t : Type) (_ : t) (x : t) : result t = Return x
+let alloc_boxed_Box_deref_mut (t : Type0) (x : t) : result (t & (t -> result t)) =
+  Return (x, (fun x -> Return x))
 
 // Trait instance
 let alloc_boxed_Box_coreopsDerefInst (self : Type0) : core_ops_deref_Deref self = {
@@ -515,7 +512,6 @@ let alloc_boxed_Box_coreopsDerefInst (self : Type0) : core_ops_deref_Deref self
 let alloc_boxed_Box_coreopsDerefMutInst (self : Type0) : core_ops_deref_DerefMut self = {
   derefInst = alloc_boxed_Box_coreopsDerefInst self;
   deref_mut = alloc_boxed_Box_deref_mut self;
-  deref_mut_back = alloc_boxed_Box_deref_mut_back self;
 }
 
 (*** Array *)
@@ -535,10 +531,18 @@ let array_index_usize (a : Type0) (n : usize) (x : array a n) (i : usize) : resu
   if i < length x then Return (index x i)
   else Fail Failure
 
-let array_update_usize (a : Type0) (n : usize) (x : array a n) (i : usize) (nx : a) : result (array a n) =
+let array_update_usize (a : Type0) (n : usize) (x : array a n) (i : usize) (nx : a) :
+  result (array a n) =
   if i < length x then Return (list_update x i nx)
   else Fail Failure
 
+let array_index_mut_usize (a : Type0) (n : usize) (x : array a n) (i : usize) :
+  result (a & (a -> result (array a n))) =
+  match array_index_usize a n x i with
+  | Fail e -> Fail e
+  | Return v ->
+    Return (v, array_update_usize a n x i)
+
 (*** Slice *)
 type slice (a : Type0) = s:list a{length s <= usize_max}
 
@@ -552,6 +556,13 @@ let slice_update_usize (a : Type0) (x : slice a) (i : usize) (nx : a) : result (
   if i < length x then Return (list_update x i nx)
   else Fail Failure
 
+let slice_index_mut_usize (a : Type0) (s : slice a) (i : usize) :
+  result (a & (a -> result (slice a))) =
+  match slice_index_usize a s i with
+  | Fail e -> Fail e
+  | Return x ->
+    Return (x, slice_update_usize a s i)
+
 (*** Subslices *)
 
 let array_to_slice (a : Type0) (n : usize) (x : array a n) : result (slice a) = Return x
@@ -559,6 +570,10 @@ let array_from_slice (a : Type0) (n : usize) (x : array a n) (s : slice a) : res
   if length s = n then Return s
   else Fail Failure
 
+let array_to_slice_mut (a : Type0) (n : usize) (x : array a n) :
+  result (slice a & (slice a -> result (array a n))) =
+  Return (x, array_from_slice a n x)
+
 // TODO: finish the definitions below (there lacks [List.drop] and [List.take] in the standard library *)
 let array_subslice (a : Type0) (n : usize) (x : array a n) (r : core_ops_range_Range usize) : result (slice a) =
   admit()
@@ -588,8 +603,13 @@ let alloc_vec_Vec_index_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) : r
 let alloc_vec_Vec_update_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
   if i < length v then Return (list_update v i x) else Fail Failure
 
-// The **forward** function shouldn't be used
-let alloc_vec_Vec_push_fwd (a  : Type0) (v : alloc_vec_Vec a) (x : a) : unit = ()
+let alloc_vec_Vec_index_mut_usize (#a : Type0) (v: alloc_vec_Vec a) (i: usize) :
+  result (a & (a → result (alloc_vec_Vec a))) =
+  match alloc_vec_Vec_index_usize v i with
+  | Return x ->
+    Return (x, alloc_vec_Vec_update_usize v i)
+  | Fail e -> Fail e
+
 let alloc_vec_Vec_push (a  : Type0) (v : alloc_vec_Vec a) (x : a) :
   Pure (result (alloc_vec_Vec a))
   (requires True)
@@ -605,9 +625,6 @@ let alloc_vec_Vec_push (a  : Type0) (v : alloc_vec_Vec a) (x : a) :
     end
   else Fail Failure
 
-// The **forward** function shouldn't be used
-let alloc_vec_Vec_insert_fwd (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result unit =
-  if i < length v then Return () else Fail Failure
 let alloc_vec_Vec_insert (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
   if i < length v then Return (list_update v i x) else Fail Failure
 
@@ -619,13 +636,11 @@ noeq type core_slice_index_SliceIndex (self t : Type0) = {
   sealedInst : core_slice_index_private_slice_index_Sealed self;
   output : Type0;
   get : self → t → result (option output);
-  get_mut : self → t → result (option output);
-  get_mut_back : self → t → option output → result t;
+  get_mut : self → t → result (option output & (option output -> result t));
   get_unchecked : self → const_raw_ptr t → result (const_raw_ptr output);
   get_unchecked_mut : self → mut_raw_ptr t → result (mut_raw_ptr output);
   index : self → t → result output;
-  index_mut : self → t → result output;
-  index_mut_back : self → t → output → result t;
+  index_mut : self → t → result (output & (output -> result t));
 }
 
 // [core::slice::index::[T]::index]: forward function
@@ -643,14 +658,8 @@ let core_slice_index_RangeUsize_get (t : Type0) (i : core_ops_range_Range usize)
   admit () // TODO
 
 // [core::slice::index::Range::get_mut]: forward function
-let core_slice_index_RangeUsize_get_mut
-  (t : Type0) : core_ops_range_Range usize → slice t → result (option (slice t)) =
-  admit () // TODO
-
-// [core::slice::index::Range::get_mut]: backward function 0
-let core_slice_index_RangeUsize_get_mut_back
-  (t : Type0) :
-  core_ops_range_Range usize → slice t → option (slice t) → result (slice t) =
+let core_slice_index_RangeUsize_get_mut (t : Type0) :
+  core_ops_range_Range usize → slice t → result (option (slice t) & (option (slice t) -> result (slice t))) =
   admit () // TODO
 
 // [core::slice::index::Range::get_unchecked]: forward function
@@ -675,27 +684,16 @@ let core_slice_index_RangeUsize_index
   admit () // TODO
 
 // [core::slice::index::Range::index_mut]: forward function
-let core_slice_index_RangeUsize_index_mut
-  (t : Type0) : core_ops_range_Range usize → slice t → result (slice t) =
-  admit () // TODO
-
-// [core::slice::index::Range::index_mut]: backward function 0
-let core_slice_index_RangeUsize_index_mut_back
-  (t : Type0) : core_ops_range_Range usize → slice t → slice t → result (slice t) =
+let core_slice_index_RangeUsize_index_mut (t : Type0) :
+  core_ops_range_Range usize → slice t → result (slice t & (slice t -> result (slice t))) =
   admit () // TODO
 
 // [core::slice::index::[T]::index_mut]: forward function
 let core_slice_index_Slice_index_mut
   (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
-  slice t → idx → result inst.output =
+  slice t → idx → result (inst.output & (inst.output -> result (slice t))) =
   admit () // 
 
-// [core::slice::index::[T]::index_mut]: backward function 0
-let core_slice_index_Slice_index_mut_back
-  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
-  slice t → idx → inst.output → result (slice t) =
-  admit () // TODO
-
 // [core::array::[T; N]::index]: forward function
 let core_array_Array_index
   (t idx : Type0) (n : usize) (inst : core_ops_index_Index (slice t) idx)
@@ -705,13 +703,8 @@ let core_array_Array_index
 // [core::array::[T; N]::index_mut]: forward function
 let core_array_Array_index_mut
   (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
-  (a : array t n) (i : idx) : result inst.indexInst.output =
-  admit () // TODO
-
-// [core::array::[T; N]::index_mut]: backward function 0
-let core_array_Array_index_mut_back
-  (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
-  (a : array t n) (i : idx) (x : inst.indexInst.output) : result (array t n) =
+  (a : array t n) (i : idx) :
+  result (inst.indexInst.output & (inst.indexInst.output -> result (array t n))) =
   admit () // TODO
 
 // Trait implementation: [core::slice::index::private_slice_index::Range]
@@ -725,12 +718,10 @@ let core_slice_index_SliceIndexRangeUsizeSliceTInst (t : Type0) :
   output = slice t;
   get = core_slice_index_RangeUsize_get t;
   get_mut = core_slice_index_RangeUsize_get_mut t;
-  get_mut_back = core_slice_index_RangeUsize_get_mut_back t;
   get_unchecked = core_slice_index_RangeUsize_get_unchecked t;
   get_unchecked_mut = core_slice_index_RangeUsize_get_unchecked_mut t;
   index = core_slice_index_RangeUsize_index t;
   index_mut = core_slice_index_RangeUsize_index_mut t;
-  index_mut_back = core_slice_index_RangeUsize_index_mut_back t;
 }
 
 // Trait implementation: [core::slice::index::[T]]
@@ -747,7 +738,6 @@ let core_ops_index_IndexMutSliceTIInst (t idx : Type0)
   core_ops_index_IndexMut (slice t) idx = {
   indexInst = core_ops_index_IndexSliceTIInst t idx inst;
   index_mut = core_slice_index_Slice_index_mut t idx inst;
-  index_mut_back = core_slice_index_Slice_index_mut_back t idx inst;
 }
 
 // Trait implementation: [core::array::[T; N]]
@@ -764,7 +754,6 @@ let core_ops_index_IndexMutArrayIInst (t idx : Type0) (n : usize)
   core_ops_index_IndexMut (array t n) idx = {
   indexInst = core_ops_index_IndexArrayInst t idx n inst.indexInst;
   index_mut = core_array_Array_index_mut t idx n inst;
-  index_mut_back = core_array_Array_index_mut_back t idx n inst;
 }
 
 // [core::slice::index::usize::get]: forward function
@@ -773,13 +762,8 @@ let core_slice_index_usize_get
   admit () // TODO
 
 // [core::slice::index::usize::get_mut]: forward function
-let core_slice_index_usize_get_mut
-  (t : Type0) : usize → slice t → result (option t) =
-  admit () // TODO
-
-// [core::slice::index::usize::get_mut]: backward function 0
-let core_slice_index_usize_get_mut_back
-  (t : Type0) : usize → slice t → option t → result (slice t) =
+let core_slice_index_usize_get_mut (t : Type0) :
+  usize → slice t → result (option t & (option t -> result (slice t))) =
   admit () // TODO
 
 // [core::slice::index::usize::get_unchecked]: forward function
@@ -797,12 +781,8 @@ let core_slice_index_usize_index (t : Type0) : usize → slice t → result t =
   admit () // TODO
 
 // [core::slice::index::usize::index_mut]: forward function
-let core_slice_index_usize_index_mut (t : Type0) : usize → slice t → result t =
-  admit () // TODO
-
-// [core::slice::index::usize::index_mut]: backward function 0
-let core_slice_index_usize_index_mut_back
-  (t : Type0) : usize → slice t → t → result (slice t) =
+let core_slice_index_usize_index_mut (t : Type0) :
+  usize → slice t → result (t & (t -> result (slice t))) =
   admit () // TODO
 
 // Trait implementation: [core::slice::index::private_slice_index::usize]
@@ -816,12 +796,10 @@ let core_slice_index_SliceIndexUsizeSliceTInst (t : Type0) :
   output = t;
   get = core_slice_index_usize_get t;
   get_mut = core_slice_index_usize_get_mut t;
-  get_mut_back = core_slice_index_usize_get_mut_back t;
   get_unchecked = core_slice_index_usize_get_unchecked t;
   get_unchecked_mut = core_slice_index_usize_get_unchecked_mut t;
   index = core_slice_index_usize_index t;
   index_mut = core_slice_index_usize_index_mut t;
-  index_mut_back = core_slice_index_usize_index_mut_back t;
 }
 
 // [alloc::vec::Vec::index]: forward function
@@ -831,13 +809,8 @@ let alloc_vec_Vec_index (t idx : Type0) (inst : core_slice_index_SliceIndex idx
 
 // [alloc::vec::Vec::index_mut]: forward function
 let alloc_vec_Vec_index_mut (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
-  (self : alloc_vec_Vec t) (i : idx) : result inst.output =
-  admit () // TODO
-
-// [alloc::vec::Vec::index_mut]: backward function 0
-let alloc_vec_Vec_index_mut_back
-  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
-  (self : alloc_vec_Vec t) (i : idx) (x : inst.output) : result (alloc_vec_Vec t) =
+  (self : alloc_vec_Vec t) (i : idx) :
+  result (inst.output & (inst.output -> result (alloc_vec_Vec t))) =
   admit () // TODO
 
 // Trait implementation: [alloc::vec::Vec]
@@ -854,7 +827,6 @@ let alloc_vec_Vec_coreopsindexIndexMutInst (t idx : Type0)
   core_ops_index_IndexMut (alloc_vec_Vec t) idx = {
   indexInst = alloc_vec_Vec_coreopsindexIndexInst t idx inst;
   index_mut = alloc_vec_Vec_index_mut t idx inst;
-  index_mut_back = alloc_vec_Vec_index_mut_back t idx inst;
 }
 
 (*** Theorems *)
@@ -870,15 +842,7 @@ let alloc_vec_Vec_index_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
 let alloc_vec_Vec_index_mut_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
   Lemma (
     alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i ==
-      alloc_vec_Vec_index_usize v i)
+      alloc_vec_Vec_index_mut_usize v i)
   [SMTPat (alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i)]
   =
   admit()
-
-let alloc_vec_Vec_index_mut_back_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) :
-  Lemma (
-    alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x ==
-      alloc_vec_Vec_update_usize v i x)
-  [SMTPat (alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x)]
-  =
-  admit()
diff --git a/tests/fstar/misc/Bitwise.fst b/tests/fstar/misc/Bitwise.fst
index d7ba2c57..7330f07a 100644
--- a/tests/fstar/misc/Bitwise.fst
+++ b/tests/fstar/misc/Bitwise.fst
@@ -5,27 +5,27 @@ open Primitives
 
 #set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
 
-(** [bitwise::shift_u32]: forward function
+(** [bitwise::shift_u32]:
     Source: 'src/bitwise.rs', lines 3:0-3:31 *)
 let shift_u32 (a : u32) : result u32 =
   let* t = u32_shr #Usize a 16 in u32_shl #Usize t 16
 
-(** [bitwise::shift_i32]: forward function
+(** [bitwise::shift_i32]:
     Source: 'src/bitwise.rs', lines 10:0-10:31 *)
 let shift_i32 (a : i32) : result i32 =
   let* t = i32_shr #Isize a 16 in i32_shl #Isize t 16
 
-(** [bitwise::xor_u32]: forward function
+(** [bitwise::xor_u32]:
     Source: 'src/bitwise.rs', lines 17:0-17:37 *)
 let xor_u32 (a : u32) (b : u32) : result u32 =
   Return (u32_xor a b)
 
-(** [bitwise::or_u32]: forward function
+(** [bitwise::or_u32]:
     Source: 'src/bitwise.rs', lines 21:0-21:36 *)
 let or_u32 (a : u32) (b : u32) : result u32 =
   Return (u32_or a b)
 
-(** [bitwise::and_u32]: forward function
+(** [bitwise::and_u32]:
     Source: 'src/bitwise.rs', lines 25:0-25:37 *)
 let and_u32 (a : u32) (b : u32) : result u32 =
   Return (u32_and a b)
diff --git a/tests/fstar/misc/Constants.fst b/tests/fstar/misc/Constants.fst
index daeefbb0..7bf42b46 100644
--- a/tests/fstar/misc/Constants.fst
+++ b/tests/fstar/misc/Constants.fst
@@ -20,7 +20,7 @@ let x1_c : u32 = eval_global x1_body
 let x2_body : result u32 = Return 3
 let x2_c : u32 = eval_global x2_body
 
-(** [constants::incr]: forward function
+(** [constants::incr]:
     Source: 'src/constants.rs', lines 17:0-17:32 *)
 let incr (n : u32) : result u32 =
   u32_add n 1
@@ -30,7 +30,7 @@ let incr (n : u32) : result u32 =
 let x3_body : result u32 = incr 32
 let x3_c : u32 = eval_global x3_body
 
-(** [constants::mk_pair0]: forward function
+(** [constants::mk_pair0]:
     Source: 'src/constants.rs', lines 23:0-23:51 *)
 let mk_pair0 (x : u32) (y : u32) : result (u32 & u32) =
   Return (x, y)
@@ -39,7 +39,7 @@ let mk_pair0 (x : u32) (y : u32) : result (u32 & u32) =
     Source: 'src/constants.rs', lines 36:0-36:23 *)
 type pair_t (t1 t2 : Type0) = { x : t1; y : t2; }
 
-(** [constants::mk_pair1]: forward function
+(** [constants::mk_pair1]:
     Source: 'src/constants.rs', lines 27:0-27:55 *)
 let mk_pair1 (x : u32) (y : u32) : result (pair_t u32 u32) =
   Return { x = x; y = y }
@@ -68,7 +68,7 @@ let p3_c : pair_t u32 u32 = eval_global p3_body
     Source: 'src/constants.rs', lines 49:0-49:18 *)
 type wrap_t (t : Type0) = { value : t; }
 
-(** [constants::{constants::Wrap<T>}::new]: forward function
+(** [constants::{constants::Wrap<T>}::new]:
     Source: 'src/constants.rs', lines 54:4-54:41 *)
 let wrap_new (t : Type0) (value : t) : result (wrap_t t) =
   Return { value = value }
@@ -78,7 +78,7 @@ let wrap_new (t : Type0) (value : t) : result (wrap_t t) =
 let y_body : result (wrap_t i32) = wrap_new i32 2
 let y_c : wrap_t i32 = eval_global y_body
 
-(** [constants::unwrap_y]: forward function
+(** [constants::unwrap_y]:
     Source: 'src/constants.rs', lines 43:0-43:30 *)
 let unwrap_y : result i32 =
   Return y_c.value
@@ -93,12 +93,12 @@ let yval_c : i32 = eval_global yval_body
 let get_z1_z1_body : result i32 = Return 3
 let get_z1_z1_c : i32 = eval_global get_z1_z1_body
 
-(** [constants::get_z1]: forward function
+(** [constants::get_z1]:
     Source: 'src/constants.rs', lines 61:0-61:28 *)
 let get_z1 : result i32 =
   Return get_z1_z1_c
 
-(** [constants::add]: forward function
+(** [constants::add]:
     Source: 'src/constants.rs', lines 66:0-66:39 *)
 let add (a : i32) (b : i32) : result i32 =
   i32_add a b
@@ -118,10 +118,10 @@ let q2_c : i32 = eval_global q2_body
 let q3_body : result i32 = add q2_c 3
 let q3_c : i32 = eval_global q3_body
 
-(** [constants::get_z2]: forward function
+(** [constants::get_z2]:
     Source: 'src/constants.rs', lines 70:0-70:28 *)
 let get_z2 : result i32 =
-  let* i = get_z1 in let* i0 = add i q3_c in add q1_c i0
+  let* i = get_z1 in let* i1 = add i q3_c in add q1_c i1
 
 (** [constants::S1]
     Source: 'src/constants.rs', lines 80:0-80:18 *)
diff --git a/tests/fstar/misc/External.Funs.fst b/tests/fstar/misc/External.Funs.fst
index 00995634..bb1b9a64 100644
--- a/tests/fstar/misc/External.Funs.fst
+++ b/tests/fstar/misc/External.Funs.fst
@@ -7,33 +7,19 @@ include External.FunsExternal
 
 #set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
 
-(** [external::swap]: forward function
+(** [external::swap]:
     Source: 'src/external.rs', lines 6:0-6:46 *)
-let swap (t : Type0) (x : t) (y : t) (st : state) : result (state & unit) =
-  let* (st0, _) = core_mem_swap t x y st in
-  let* (st1, _) = core_mem_swap_back0 t x y st st0 in
-  let* (st2, _) = core_mem_swap_back1 t x y st st1 in
-  Return (st2, ())
+let swap (t : Type0) (x : t) (y : t) (st : state) : result (state & (t & t)) =
+  core_mem_swap t x y st
 
-(** [external::swap]: backward function 0
-    Source: 'src/external.rs', lines 6:0-6:46 *)
-let swap_back
-  (t : Type0) (x : t) (y : t) (st : state) (st0 : state) :
-  result (state & (t & t))
-  =
-  let* (st1, _) = core_mem_swap t x y st in
-  let* (st2, x0) = core_mem_swap_back0 t x y st st1 in
-  let* (_, y0) = core_mem_swap_back1 t x y st st2 in
-  Return (st0, (x0, y0))
-
-(** [external::test_new_non_zero_u32]: forward function
+(** [external::test_new_non_zero_u32]:
     Source: 'src/external.rs', lines 11:0-11:60 *)
 let test_new_non_zero_u32
   (x : u32) (st : state) : result (state & core_num_nonzero_NonZeroU32_t) =
-  let* (st0, o) = core_num_nonzero_NonZeroU32_new x st in
-  core_option_Option_unwrap core_num_nonzero_NonZeroU32_t o st0
+  let* (st1, o) = core_num_nonzero_NonZeroU32_new x st in
+  core_option_Option_unwrap core_num_nonzero_NonZeroU32_t o st1
 
-(** [external::test_vec]: forward function
+(** [external::test_vec]:
     Source: 'src/external.rs', lines 17:0-17:17 *)
 let test_vec : result unit =
   let v = alloc_vec_Vec_new u32 in
@@ -43,42 +29,28 @@ let test_vec : result unit =
 (** Unit test for [external::test_vec] *)
 let _ = assert_norm (test_vec = Return ())
 
-(** [external::custom_swap]: forward function
-    Source: 'src/external.rs', lines 24:0-24:66 *)
-let custom_swap (t : Type0) (x : t) (y : t) (st : state) : result (state & t) =
-  let* (st0, _) = core_mem_swap t x y st in
-  let* (st1, x0) = core_mem_swap_back0 t x y st st0 in
-  let* (st2, _) = core_mem_swap_back1 t x y st st1 in
-  Return (st2, x0)
-
-(** [external::custom_swap]: backward function 0
+(** [external::custom_swap]:
     Source: 'src/external.rs', lines 24:0-24:66 *)
-let custom_swap_back
-  (t : Type0) (x : t) (y : t) (st : state) (ret : t) (st0 : state) :
-  result (state & (t & t))
+let custom_swap
+  (t : Type0) (x : t) (y : t) (st : state) :
+  result (state & (t & (t -> state -> result (state & (t & t)))))
   =
-  let* (st1, _) = core_mem_swap t x y st in
-  let* (st2, _) = core_mem_swap_back0 t x y st st1 in
-  let* (_, y0) = core_mem_swap_back1 t x y st st2 in
-  Return (st0, (ret, y0))
-
-(** [external::test_custom_swap]: forward function
-    Source: 'src/external.rs', lines 29:0-29:59 *)
-let test_custom_swap (x : u32) (y : u32) (st : state) : result (state & unit) =
-  let* (st0, _) = custom_swap u32 x y st in Return (st0, ())
+  let* (st1, (x1, x2)) = core_mem_swap t x y st in
+  let back_'a = fun ret st2 -> Return (st2, (ret, x2)) in
+  Return (st1, (x1, back_'a))
 
-(** [external::test_custom_swap]: backward function 0
+(** [external::test_custom_swap]:
     Source: 'src/external.rs', lines 29:0-29:59 *)
-let test_custom_swap_back
-  (x : u32) (y : u32) (st : state) (st0 : state) :
-  result (state & (u32 & u32))
-  =
-  custom_swap_back u32 x y st 1 st0
+let test_custom_swap
+  (x : u32) (y : u32) (st : state) : result (state & (u32 & u32)) =
+  let* (st1, (_, custom_swap_back)) = custom_swap u32 x y st in
+  let* (_, (x1, y1)) = custom_swap_back 1 st1 in
+  Return (st1, (x1, y1))
 
-(** [external::test_swap_non_zero]: forward function
+(** [external::test_swap_non_zero]:
     Source: 'src/external.rs', lines 35:0-35:44 *)
 let test_swap_non_zero (x : u32) (st : state) : result (state & u32) =
-  let* (st0, _) = swap u32 x 0 st in
-  let* (st1, (x0, _)) = swap_back u32 x 0 st st0 in
-  if x0 = 0 then Fail Failure else Return (st1, x0)
+  let* (st1, p) = swap u32 x 0 st in
+  let (x1, _) = p in
+  if x1 = 0 then Fail Failure else Return (st1, x1)
 
diff --git a/tests/fstar/misc/External.FunsExternal.fsti b/tests/fstar/misc/External.FunsExternal.fsti
index 923a1101..a412aea9 100644
--- a/tests/fstar/misc/External.FunsExternal.fsti
+++ b/tests/fstar/misc/External.FunsExternal.fsti
@@ -6,26 +6,16 @@ include External.Types
 
 #set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
 
-(** [core::mem::swap]: forward function
+(** [core::mem::swap]:
     Source: '/rustc/d59363ad0b6391b7fc5bbb02c9ccf9300eef3753/library/core/src/mem/mod.rs', lines 726:0-726:42 *)
-val core_mem_swap (t : Type0) : t -> t -> state -> result (state & unit)
+val core_mem_swap (t : Type0) : t -> t -> state -> result (state & (t & t))
 
-(** [core::mem::swap]: backward function 0
-    Source: '/rustc/d59363ad0b6391b7fc5bbb02c9ccf9300eef3753/library/core/src/mem/mod.rs', lines 726:0-726:42 *)
-val core_mem_swap_back0
-  (t : Type0) : t -> t -> state -> state -> result (state & t)
-
-(** [core::mem::swap]: backward function 1
-    Source: '/rustc/d59363ad0b6391b7fc5bbb02c9ccf9300eef3753/library/core/src/mem/mod.rs', lines 726:0-726:42 *)
-val core_mem_swap_back1
-  (t : Type0) : t -> t -> state -> state -> result (state & t)
-
-(** [core::num::nonzero::{core::num::nonzero::NonZeroU32#14}::new]: forward function
+(** [core::num::nonzero::{core::num::nonzero::NonZeroU32#14}::new]:
     Source: '/rustc/d59363ad0b6391b7fc5bbb02c9ccf9300eef3753/library/core/src/num/nonzero.rs', lines 79:16-79:57 *)
 val core_num_nonzero_NonZeroU32_new
   : u32 -> state -> result (state & (option core_num_nonzero_NonZeroU32_t))
 
-(** [core::option::{core::option::Option<T>}::unwrap]: forward function
+(** [core::option::{core::option::Option<T>}::unwrap]:
     Source: '/rustc/d59363ad0b6391b7fc5bbb02c9ccf9300eef3753/library/core/src/option.rs', lines 932:4-932:34 *)
 val core_option_Option_unwrap
   (t : Type0) : option t -> state -> result (state & t)
diff --git a/tests/fstar/misc/Loops.Funs.fst b/tests/fstar/misc/Loops.Funs.fst
index d2ac5561..a047c170 100644
--- a/tests/fstar/misc/Loops.Funs.fst
+++ b/tests/fstar/misc/Loops.Funs.fst
@@ -7,22 +7,22 @@ include Loops.Clauses
 
 #set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
 
-(** [loops::sum]: loop 0: forward function
+(** [loops::sum]: loop 0:
     Source: 'src/loops.rs', lines 4:0-14:1 *)
 let rec sum_loop
   (max : u32) (i : u32) (s : u32) :
   Tot (result u32) (decreases (sum_loop_decreases max i s))
   =
   if i < max
-  then let* s0 = u32_add s i in let* i0 = u32_add i 1 in sum_loop max i0 s0
+  then let* s1 = u32_add s i in let* i1 = u32_add i 1 in sum_loop max i1 s1
   else u32_mul s 2
 
-(** [loops::sum]: forward function
+(** [loops::sum]:
     Source: 'src/loops.rs', lines 4:0-4:27 *)
 let sum (max : u32) : result u32 =
   sum_loop max 0 0
 
-(** [loops::sum_with_mut_borrows]: loop 0: forward function
+(** [loops::sum_with_mut_borrows]: loop 0:
     Source: 'src/loops.rs', lines 19:0-31:1 *)
 let rec sum_with_mut_borrows_loop
   (max : u32) (mi : u32) (ms : u32) :
@@ -30,17 +30,17 @@ let rec sum_with_mut_borrows_loop
   =
   if mi < max
   then
-    let* ms0 = u32_add ms mi in
-    let* mi0 = u32_add mi 1 in
-    sum_with_mut_borrows_loop max mi0 ms0
+    let* ms1 = u32_add ms mi in
+    let* mi1 = u32_add mi 1 in
+    sum_with_mut_borrows_loop max mi1 ms1
   else u32_mul ms 2
 
-(** [loops::sum_with_mut_borrows]: forward function
+(** [loops::sum_with_mut_borrows]:
     Source: 'src/loops.rs', lines 19:0-19:44 *)
 let sum_with_mut_borrows (max : u32) : result u32 =
   sum_with_mut_borrows_loop max 0 0
 
-(** [loops::sum_with_shared_borrows]: loop 0: forward function
+(** [loops::sum_with_shared_borrows]: loop 0:
     Source: 'src/loops.rs', lines 34:0-48:1 *)
 let rec sum_with_shared_borrows_loop
   (max : u32) (i : u32) (s : u32) :
@@ -48,40 +48,39 @@ let rec sum_with_shared_borrows_loop
   =
   if i < max
   then
-    let* i0 = u32_add i 1 in
-    let* s0 = u32_add s i0 in
-    sum_with_shared_borrows_loop max i0 s0
+    let* i1 = u32_add i 1 in
+    let* s1 = u32_add s i1 in
+    sum_with_shared_borrows_loop max i1 s1
   else u32_mul s 2
 
-(** [loops::sum_with_shared_borrows]: forward function
+(** [loops::sum_with_shared_borrows]:
     Source: 'src/loops.rs', lines 34:0-34:47 *)
 let sum_with_shared_borrows (max : u32) : result u32 =
   sum_with_shared_borrows_loop max 0 0
 
-(** [loops::clear]: loop 0: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [loops::clear]: loop 0:
     Source: 'src/loops.rs', lines 52:0-58:1 *)
 let rec clear_loop
   (v : alloc_vec_Vec u32) (i : usize) :
   Tot (result (alloc_vec_Vec u32)) (decreases (clear_loop_decreases v i))
   =
-  let i0 = alloc_vec_Vec_len u32 v in
-  if i < i0
+  let i1 = alloc_vec_Vec_len u32 v in
+  if i < i1
   then
-    let* i1 = usize_add i 1 in
-    let* v0 =
-      alloc_vec_Vec_index_mut_back u32 usize
-        (core_slice_index_SliceIndexUsizeSliceTInst u32) v i 0 in
-    clear_loop v0 i1
+    let* (_, index_mut_back) =
+      alloc_vec_Vec_index_mut u32 usize
+        (core_slice_index_SliceIndexUsizeSliceTInst u32) v i in
+    let* i2 = usize_add i 1 in
+    let* v1 = index_mut_back 0 in
+    clear_loop v1 i2
   else Return v
 
-(** [loops::clear]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [loops::clear]:
     Source: 'src/loops.rs', lines 52:0-52:30 *)
 let clear (v : alloc_vec_Vec u32) : result (alloc_vec_Vec u32) =
   clear_loop v 0
 
-(** [loops::list_mem]: loop 0: forward function
+(** [loops::list_mem]: loop 0:
     Source: 'src/loops.rs', lines 66:0-75:1 *)
 let rec list_mem_loop
   (x : u32) (ls : list_t u32) :
@@ -92,54 +91,41 @@ let rec list_mem_loop
   | List_Nil -> Return false
   end
 
-(** [loops::list_mem]: forward function
+(** [loops::list_mem]:
     Source: 'src/loops.rs', lines 66:0-66:52 *)
 let list_mem (x : u32) (ls : list_t u32) : result bool =
   list_mem_loop x ls
 
-(** [loops::list_nth_mut_loop]: loop 0: forward function
+(** [loops::list_nth_mut_loop]: loop 0:
     Source: 'src/loops.rs', lines 78:0-88:1 *)
 let rec list_nth_mut_loop_loop
   (t : Type0) (ls : list_t t) (i : u32) :
-  Tot (result t) (decreases (list_nth_mut_loop_loop_decreases t ls i))
+  Tot (result (t & (t -> result (list_t t))))
+  (decreases (list_nth_mut_loop_loop_decreases t ls i))
   =
   begin match ls with
   | List_Cons x tl ->
     if i = 0
-    then Return x
-    else let* i0 = u32_sub i 1 in list_nth_mut_loop_loop t tl i0
-  | List_Nil -> Fail Failure
-  end
-
-(** [loops::list_nth_mut_loop]: forward function
-    Source: 'src/loops.rs', lines 78:0-78:71 *)
-let list_nth_mut_loop (t : Type0) (ls : list_t t) (i : u32) : result t =
-  list_nth_mut_loop_loop t ls i
-
-(** [loops::list_nth_mut_loop]: loop 0: backward function 0
-    Source: 'src/loops.rs', lines 78:0-88:1 *)
-let rec list_nth_mut_loop_loop_back
-  (t : Type0) (ls : list_t t) (i : u32) (ret : t) :
-  Tot (result (list_t t)) (decreases (list_nth_mut_loop_loop_decreases t ls i))
-  =
-  begin match ls with
-  | List_Cons x tl ->
-    if i = 0
-    then Return (List_Cons ret tl)
+    then let back = fun ret -> Return (List_Cons ret tl) in Return (x, back)
     else
-      let* i0 = u32_sub i 1 in
-      let* tl0 = list_nth_mut_loop_loop_back t tl i0 ret in
-      Return (List_Cons x tl0)
+      let* i1 = u32_sub i 1 in
+      let* (x1, back) = list_nth_mut_loop_loop t tl i1 in
+      let back1 = fun ret -> let* tl1 = back ret in Return (List_Cons x tl1) in
+      Return (x1, back1)
   | List_Nil -> Fail Failure
   end
 
-(** [loops::list_nth_mut_loop]: backward function 0
+(** [loops::list_nth_mut_loop]:
     Source: 'src/loops.rs', lines 78:0-78:71 *)
-let list_nth_mut_loop_back
-  (t : Type0) (ls : list_t t) (i : u32) (ret : t) : result (list_t t) =
-  list_nth_mut_loop_loop_back t ls i ret
+let list_nth_mut_loop
+  (t : Type0) (ls : list_t t) (i : u32) :
+  result (t & (t -> result (list_t t)))
+  =
+  let* (x, back) = list_nth_mut_loop_loop t ls i in
+  let back1 = fun ret -> back ret in
+  Return (x, back1)
 
-(** [loops::list_nth_shared_loop]: loop 0: forward function
+(** [loops::list_nth_shared_loop]: loop 0:
     Source: 'src/loops.rs', lines 91:0-101:1 *)
 let rec list_nth_shared_loop_loop
   (t : Type0) (ls : list_t t) (i : u32) :
@@ -149,63 +135,47 @@ let rec list_nth_shared_loop_loop
   | List_Cons x tl ->
     if i = 0
     then Return x
-    else let* i0 = u32_sub i 1 in list_nth_shared_loop_loop t tl i0
+    else let* i1 = u32_sub i 1 in list_nth_shared_loop_loop t tl i1
   | List_Nil -> Fail Failure
   end
 
-(** [loops::list_nth_shared_loop]: forward function
+(** [loops::list_nth_shared_loop]:
     Source: 'src/loops.rs', lines 91:0-91:66 *)
 let list_nth_shared_loop (t : Type0) (ls : list_t t) (i : u32) : result t =
   list_nth_shared_loop_loop t ls i
 
-(** [loops::get_elem_mut]: loop 0: forward function
+(** [loops::get_elem_mut]: loop 0:
     Source: 'src/loops.rs', lines 103:0-117:1 *)
 let rec get_elem_mut_loop
   (x : usize) (ls : list_t usize) :
-  Tot (result usize) (decreases (get_elem_mut_loop_decreases x ls))
-  =
-  begin match ls with
-  | List_Cons y tl -> if y = x then Return y else get_elem_mut_loop x tl
-  | List_Nil -> Fail Failure
-  end
-
-(** [loops::get_elem_mut]: forward function
-    Source: 'src/loops.rs', lines 103:0-103:73 *)
-let get_elem_mut
-  (slots : alloc_vec_Vec (list_t usize)) (x : usize) : result usize =
-  let* l =
-    alloc_vec_Vec_index_mut (list_t usize) usize
-      (core_slice_index_SliceIndexUsizeSliceTInst (list_t usize)) slots 0 in
-  get_elem_mut_loop x l
-
-(** [loops::get_elem_mut]: loop 0: backward function 0
-    Source: 'src/loops.rs', lines 103:0-117:1 *)
-let rec get_elem_mut_loop_back
-  (x : usize) (ls : list_t usize) (ret : usize) :
-  Tot (result (list_t usize)) (decreases (get_elem_mut_loop_decreases x ls))
+  Tot (result (usize & (usize -> result (list_t usize))))
+  (decreases (get_elem_mut_loop_decreases x ls))
   =
   begin match ls with
   | List_Cons y tl ->
     if y = x
-    then Return (List_Cons ret tl)
-    else let* tl0 = get_elem_mut_loop_back x tl ret in Return (List_Cons y tl0)
+    then let back = fun ret -> Return (List_Cons ret tl) in Return (y, back)
+    else
+      let* (i, back) = get_elem_mut_loop x tl in
+      let back1 = fun ret -> let* tl1 = back ret in Return (List_Cons y tl1) in
+      Return (i, back1)
   | List_Nil -> Fail Failure
   end
 
-(** [loops::get_elem_mut]: backward function 0
+(** [loops::get_elem_mut]:
     Source: 'src/loops.rs', lines 103:0-103:73 *)
-let get_elem_mut_back
-  (slots : alloc_vec_Vec (list_t usize)) (x : usize) (ret : usize) :
-  result (alloc_vec_Vec (list_t usize))
+let get_elem_mut
+  (slots : alloc_vec_Vec (list_t usize)) (x : usize) :
+  result (usize & (usize -> result (alloc_vec_Vec (list_t usize))))
   =
-  let* l =
+  let* (l, index_mut_back) =
     alloc_vec_Vec_index_mut (list_t usize) usize
       (core_slice_index_SliceIndexUsizeSliceTInst (list_t usize)) slots 0 in
-  let* l0 = get_elem_mut_loop_back x l ret in
-  alloc_vec_Vec_index_mut_back (list_t usize) usize
-    (core_slice_index_SliceIndexUsizeSliceTInst (list_t usize)) slots 0 l0
+  let* (i, back) = get_elem_mut_loop x l in
+  let back1 = fun ret -> let* l1 = back ret in index_mut_back l1 in
+  Return (i, back1)
 
-(** [loops::get_elem_shared]: loop 0: forward function
+(** [loops::get_elem_shared]: loop 0:
     Source: 'src/loops.rs', lines 119:0-133:1 *)
 let rec get_elem_shared_loop
   (x : usize) (ls : list_t usize) :
@@ -216,7 +186,7 @@ let rec get_elem_shared_loop
   | List_Nil -> Fail Failure
   end
 
-(** [loops::get_elem_shared]: forward function
+(** [loops::get_elem_shared]:
     Source: 'src/loops.rs', lines 119:0-119:68 *)
 let get_elem_shared
   (slots : alloc_vec_Vec (list_t usize)) (x : usize) : result usize =
@@ -225,69 +195,50 @@ let get_elem_shared
       (core_slice_index_SliceIndexUsizeSliceTInst (list_t usize)) slots 0 in
   get_elem_shared_loop x l
 
-(** [loops::id_mut]: forward function
-    Source: 'src/loops.rs', lines 135:0-135:50 *)
-let id_mut (t : Type0) (ls : list_t t) : result (list_t t) =
-  Return ls
-
-(** [loops::id_mut]: backward function 0
+(** [loops::id_mut]:
     Source: 'src/loops.rs', lines 135:0-135:50 *)
-let id_mut_back
-  (t : Type0) (ls : list_t t) (ret : list_t t) : result (list_t t) =
-  Return ret
+let id_mut
+  (t : Type0) (ls : list_t t) :
+  result ((list_t t) & (list_t t -> result (list_t t)))
+  =
+  let back = fun ret -> Return ret in Return (ls, back)
 
-(** [loops::id_shared]: forward function
+(** [loops::id_shared]:
     Source: 'src/loops.rs', lines 139:0-139:45 *)
 let id_shared (t : Type0) (ls : list_t t) : result (list_t t) =
   Return ls
 
-(** [loops::list_nth_mut_loop_with_id]: loop 0: forward function
+(** [loops::list_nth_mut_loop_with_id]: loop 0:
     Source: 'src/loops.rs', lines 144:0-155:1 *)
 let rec list_nth_mut_loop_with_id_loop
   (t : Type0) (i : u32) (ls : list_t t) :
-  Tot (result t) (decreases (list_nth_mut_loop_with_id_loop_decreases t i ls))
-  =
-  begin match ls with
-  | List_Cons x tl ->
-    if i = 0
-    then Return x
-    else let* i0 = u32_sub i 1 in list_nth_mut_loop_with_id_loop t i0 tl
-  | List_Nil -> Fail Failure
-  end
-
-(** [loops::list_nth_mut_loop_with_id]: forward function
-    Source: 'src/loops.rs', lines 144:0-144:75 *)
-let list_nth_mut_loop_with_id
-  (t : Type0) (ls : list_t t) (i : u32) : result t =
-  let* ls0 = id_mut t ls in list_nth_mut_loop_with_id_loop t i ls0
-
-(** [loops::list_nth_mut_loop_with_id]: loop 0: backward function 0
-    Source: 'src/loops.rs', lines 144:0-155:1 *)
-let rec list_nth_mut_loop_with_id_loop_back
-  (t : Type0) (i : u32) (ls : list_t t) (ret : t) :
-  Tot (result (list_t t))
+  Tot (result (t & (t -> result (list_t t))))
   (decreases (list_nth_mut_loop_with_id_loop_decreases t i ls))
   =
   begin match ls with
   | List_Cons x tl ->
     if i = 0
-    then Return (List_Cons ret tl)
+    then let back = fun ret -> Return (List_Cons ret tl) in Return (x, back)
     else
-      let* i0 = u32_sub i 1 in
-      let* tl0 = list_nth_mut_loop_with_id_loop_back t i0 tl ret in
-      Return (List_Cons x tl0)
+      let* i1 = u32_sub i 1 in
+      let* (x1, back) = list_nth_mut_loop_with_id_loop t i1 tl in
+      let back1 = fun ret -> let* tl1 = back ret in Return (List_Cons x tl1) in
+      Return (x1, back1)
   | List_Nil -> Fail Failure
   end
 
-(** [loops::list_nth_mut_loop_with_id]: backward function 0
+(** [loops::list_nth_mut_loop_with_id]:
     Source: 'src/loops.rs', lines 144:0-144:75 *)
-let list_nth_mut_loop_with_id_back
-  (t : Type0) (ls : list_t t) (i : u32) (ret : t) : result (list_t t) =
-  let* ls0 = id_mut t ls in
-  let* l = list_nth_mut_loop_with_id_loop_back t i ls0 ret in
-  id_mut_back t ls l
+let list_nth_mut_loop_with_id
+  (t : Type0) (ls : list_t t) (i : u32) :
+  result (t & (t -> result (list_t t)))
+  =
+  let* (ls1, id_mut_back) = id_mut t ls in
+  let* (x, back) = list_nth_mut_loop_with_id_loop t i ls1 in
+  let back1 = fun ret -> let* l = back ret in id_mut_back l in
+  Return (x, back1)
 
-(** [loops::list_nth_shared_loop_with_id]: loop 0: forward function
+(** [loops::list_nth_shared_loop_with_id]: loop 0:
     Source: 'src/loops.rs', lines 158:0-169:1 *)
 let rec list_nth_shared_loop_with_id_loop
   (t : Type0) (i : u32) (ls : list_t t) :
@@ -298,46 +249,21 @@ let rec list_nth_shared_loop_with_id_loop
   | List_Cons x tl ->
     if i = 0
     then Return x
-    else let* i0 = u32_sub i 1 in list_nth_shared_loop_with_id_loop t i0 tl
+    else let* i1 = u32_sub i 1 in list_nth_shared_loop_with_id_loop t i1 tl
   | List_Nil -> Fail Failure
   end
 
-(** [loops::list_nth_shared_loop_with_id]: forward function
+(** [loops::list_nth_shared_loop_with_id]:
     Source: 'src/loops.rs', lines 158:0-158:70 *)
 let list_nth_shared_loop_with_id
   (t : Type0) (ls : list_t t) (i : u32) : result t =
-  let* ls0 = id_shared t ls in list_nth_shared_loop_with_id_loop t i ls0
+  let* ls1 = id_shared t ls in list_nth_shared_loop_with_id_loop t i ls1
 
-(** [loops::list_nth_mut_loop_pair]: loop 0: forward function
+(** [loops::list_nth_mut_loop_pair]: loop 0:
     Source: 'src/loops.rs', lines 174:0-195:1 *)
 let rec list_nth_mut_loop_pair_loop
   (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
-  Tot (result (t & t))
-  (decreases (list_nth_mut_loop_pair_loop_decreases t ls0 ls1 i))
-  =
-  begin match ls0 with
-  | List_Cons x0 tl0 ->
-    begin match ls1 with
-    | List_Cons x1 tl1 ->
-      if i = 0
-      then Return (x0, x1)
-      else let* i0 = u32_sub i 1 in list_nth_mut_loop_pair_loop t tl0 tl1 i0
-    | List_Nil -> Fail Failure
-    end
-  | List_Nil -> Fail Failure
-  end
-
-(** [loops::list_nth_mut_loop_pair]: forward function
-    Source: 'src/loops.rs', lines 174:0-178:27 *)
-let list_nth_mut_loop_pair
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) : result (t & t) =
-  list_nth_mut_loop_pair_loop t ls0 ls1 i
-
-(** [loops::list_nth_mut_loop_pair]: loop 0: backward function 0
-    Source: 'src/loops.rs', lines 174:0-195:1 *)
-let rec list_nth_mut_loop_pair_loop_back'a
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
-  Tot (result (list_t t))
+  Tot (result ((t & t) & (t -> result (list_t t)) & (t -> result (list_t t))))
   (decreases (list_nth_mut_loop_pair_loop_decreases t ls0 ls1 i))
   =
   begin match ls0 with
@@ -345,55 +271,36 @@ let rec list_nth_mut_loop_pair_loop_back'a
     begin match ls1 with
     | List_Cons x1 tl1 ->
       if i = 0
-      then Return (List_Cons ret tl0)
+      then
+        let back_'a = fun ret -> Return (List_Cons ret tl0) in
+        let back_'b = fun ret -> Return (List_Cons ret tl1) in
+        Return ((x0, x1), back_'a, back_'b)
       else
-        let* i0 = u32_sub i 1 in
-        let* tl00 = list_nth_mut_loop_pair_loop_back'a t tl0 tl1 i0 ret in
-        Return (List_Cons x0 tl00)
+        let* i1 = u32_sub i 1 in
+        let* (p, back_'a, back_'b) = list_nth_mut_loop_pair_loop t tl0 tl1 i1
+          in
+        let back_'a1 =
+          fun ret -> let* tl01 = back_'a ret in Return (List_Cons x0 tl01) in
+        let back_'b1 =
+          fun ret -> let* tl11 = back_'b ret in Return (List_Cons x1 tl11) in
+        Return (p, back_'a1, back_'b1)
     | List_Nil -> Fail Failure
     end
   | List_Nil -> Fail Failure
   end
 
-(** [loops::list_nth_mut_loop_pair]: backward function 0
+(** [loops::list_nth_mut_loop_pair]:
     Source: 'src/loops.rs', lines 174:0-178:27 *)
-let list_nth_mut_loop_pair_back'a
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
-  result (list_t t)
-  =
-  list_nth_mut_loop_pair_loop_back'a t ls0 ls1 i ret
-
-(** [loops::list_nth_mut_loop_pair]: loop 0: backward function 1
-    Source: 'src/loops.rs', lines 174:0-195:1 *)
-let rec list_nth_mut_loop_pair_loop_back'b
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
-  Tot (result (list_t t))
-  (decreases (list_nth_mut_loop_pair_loop_decreases t ls0 ls1 i))
-  =
-  begin match ls0 with
-  | List_Cons x0 tl0 ->
-    begin match ls1 with
-    | List_Cons x1 tl1 ->
-      if i = 0
-      then Return (List_Cons ret tl1)
-      else
-        let* i0 = u32_sub i 1 in
-        let* tl10 = list_nth_mut_loop_pair_loop_back'b t tl0 tl1 i0 ret in
-        Return (List_Cons x1 tl10)
-    | List_Nil -> Fail Failure
-    end
-  | List_Nil -> Fail Failure
-  end
-
-(** [loops::list_nth_mut_loop_pair]: backward function 1
-    Source: 'src/loops.rs', lines 174:0-178:27 *)
-let list_nth_mut_loop_pair_back'b
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
-  result (list_t t)
+let list_nth_mut_loop_pair
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
+  result ((t & t) & (t -> result (list_t t)) & (t -> result (list_t t)))
   =
-  list_nth_mut_loop_pair_loop_back'b t ls0 ls1 i ret
+  let* (p, back_'a, back_'b) = list_nth_mut_loop_pair_loop t ls0 ls1 i in
+  let back_'a1 = fun ret -> back_'a ret in
+  let back_'b1 = fun ret -> back_'b ret in
+  Return (p, back_'a1, back_'b1)
 
-(** [loops::list_nth_shared_loop_pair]: loop 0: forward function
+(** [loops::list_nth_shared_loop_pair]: loop 0:
     Source: 'src/loops.rs', lines 198:0-219:1 *)
 let rec list_nth_shared_loop_pair_loop
   (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
@@ -406,23 +313,23 @@ let rec list_nth_shared_loop_pair_loop
     | List_Cons x1 tl1 ->
       if i = 0
       then Return (x0, x1)
-      else let* i0 = u32_sub i 1 in list_nth_shared_loop_pair_loop t tl0 tl1 i0
+      else let* i1 = u32_sub i 1 in list_nth_shared_loop_pair_loop t tl0 tl1 i1
     | List_Nil -> Fail Failure
     end
   | List_Nil -> Fail Failure
   end
 
-(** [loops::list_nth_shared_loop_pair]: forward function
+(** [loops::list_nth_shared_loop_pair]:
     Source: 'src/loops.rs', lines 198:0-202:19 *)
 let list_nth_shared_loop_pair
   (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) : result (t & t) =
   list_nth_shared_loop_pair_loop t ls0 ls1 i
 
-(** [loops::list_nth_mut_loop_pair_merge]: loop 0: forward function
+(** [loops::list_nth_mut_loop_pair_merge]: loop 0:
     Source: 'src/loops.rs', lines 223:0-238:1 *)
 let rec list_nth_mut_loop_pair_merge_loop
   (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
-  Tot (result (t & t))
+  Tot (result ((t & t) & ((t & t) -> result ((list_t t) & (list_t t)))))
   (decreases (list_nth_mut_loop_pair_merge_loop_decreases t ls0 ls1 i))
   =
   begin match ls0 with
@@ -430,52 +337,35 @@ let rec list_nth_mut_loop_pair_merge_loop
     begin match ls1 with
     | List_Cons x1 tl1 ->
       if i = 0
-      then Return (x0, x1)
+      then
+        let back_'a =
+          fun ret ->
+            let (x, x2) = ret in Return (List_Cons x tl0, List_Cons x2 tl1) in
+        Return ((x0, x1), back_'a)
       else
-        let* i0 = u32_sub i 1 in list_nth_mut_loop_pair_merge_loop t tl0 tl1 i0
+        let* i1 = u32_sub i 1 in
+        let* (p, back_'a) = list_nth_mut_loop_pair_merge_loop t tl0 tl1 i1 in
+        let back_'a1 =
+          fun ret ->
+            let* (tl01, tl11) = back_'a ret in
+            Return (List_Cons x0 tl01, List_Cons x1 tl11) in
+        Return (p, back_'a1)
     | List_Nil -> Fail Failure
     end
   | List_Nil -> Fail Failure
   end
 
-(** [loops::list_nth_mut_loop_pair_merge]: forward function
+(** [loops::list_nth_mut_loop_pair_merge]:
     Source: 'src/loops.rs', lines 223:0-227:27 *)
 let list_nth_mut_loop_pair_merge
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) : result (t & t) =
-  list_nth_mut_loop_pair_merge_loop t ls0 ls1 i
-
-(** [loops::list_nth_mut_loop_pair_merge]: loop 0: backward function 0
-    Source: 'src/loops.rs', lines 223:0-238:1 *)
-let rec list_nth_mut_loop_pair_merge_loop_back
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : (t & t)) :
-  Tot (result ((list_t t) & (list_t t)))
-  (decreases (list_nth_mut_loop_pair_merge_loop_decreases t ls0 ls1 i))
-  =
-  begin match ls0 with
-  | List_Cons x0 tl0 ->
-    begin match ls1 with
-    | List_Cons x1 tl1 ->
-      if i = 0
-      then let (x, x2) = ret in Return (List_Cons x tl0, List_Cons x2 tl1)
-      else
-        let* i0 = u32_sub i 1 in
-        let* (tl00, tl10) =
-          list_nth_mut_loop_pair_merge_loop_back t tl0 tl1 i0 ret in
-        Return (List_Cons x0 tl00, List_Cons x1 tl10)
-    | List_Nil -> Fail Failure
-    end
-  | List_Nil -> Fail Failure
-  end
-
-(** [loops::list_nth_mut_loop_pair_merge]: backward function 0
-    Source: 'src/loops.rs', lines 223:0-227:27 *)
-let list_nth_mut_loop_pair_merge_back
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : (t & t)) :
-  result ((list_t t) & (list_t t))
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
+  result ((t & t) & ((t & t) -> result ((list_t t) & (list_t t))))
   =
-  list_nth_mut_loop_pair_merge_loop_back t ls0 ls1 i ret
+  let* (p, back_'a) = list_nth_mut_loop_pair_merge_loop t ls0 ls1 i in
+  let back_'a1 = fun ret -> back_'a ret in
+  Return (p, back_'a1)
 
-(** [loops::list_nth_shared_loop_pair_merge]: loop 0: forward function
+(** [loops::list_nth_shared_loop_pair_merge]: loop 0:
     Source: 'src/loops.rs', lines 241:0-256:1 *)
 let rec list_nth_shared_loop_pair_merge_loop
   (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
@@ -489,24 +379,24 @@ let rec list_nth_shared_loop_pair_merge_loop
       if i = 0
       then Return (x0, x1)
       else
-        let* i0 = u32_sub i 1 in
-        list_nth_shared_loop_pair_merge_loop t tl0 tl1 i0
+        let* i1 = u32_sub i 1 in
+        list_nth_shared_loop_pair_merge_loop t tl0 tl1 i1
     | List_Nil -> Fail Failure
     end
   | List_Nil -> Fail Failure
   end
 
-(** [loops::list_nth_shared_loop_pair_merge]: forward function
+(** [loops::list_nth_shared_loop_pair_merge]:
     Source: 'src/loops.rs', lines 241:0-245:19 *)
 let list_nth_shared_loop_pair_merge
   (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) : result (t & t) =
   list_nth_shared_loop_pair_merge_loop t ls0 ls1 i
 
-(** [loops::list_nth_mut_shared_loop_pair]: loop 0: forward function
+(** [loops::list_nth_mut_shared_loop_pair]: loop 0:
     Source: 'src/loops.rs', lines 259:0-274:1 *)
 let rec list_nth_mut_shared_loop_pair_loop
   (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
-  Tot (result (t & t))
+  Tot (result ((t & t) & (t -> result (list_t t))))
   (decreases (list_nth_mut_shared_loop_pair_loop_decreases t ls0 ls1 i))
   =
   begin match ls0 with
@@ -514,56 +404,35 @@ let rec list_nth_mut_shared_loop_pair_loop
     begin match ls1 with
     | List_Cons x1 tl1 ->
       if i = 0
-      then Return (x0, x1)
+      then
+        let back_'a = fun ret -> Return (List_Cons ret tl0) in
+        Return ((x0, x1), back_'a)
       else
-        let* i0 = u32_sub i 1 in
-        list_nth_mut_shared_loop_pair_loop t tl0 tl1 i0
+        let* i1 = u32_sub i 1 in
+        let* (p, back_'a) = list_nth_mut_shared_loop_pair_loop t tl0 tl1 i1 in
+        let back_'a1 =
+          fun ret -> let* tl01 = back_'a ret in Return (List_Cons x0 tl01) in
+        Return (p, back_'a1)
     | List_Nil -> Fail Failure
     end
   | List_Nil -> Fail Failure
   end
 
-(** [loops::list_nth_mut_shared_loop_pair]: forward function
+(** [loops::list_nth_mut_shared_loop_pair]:
     Source: 'src/loops.rs', lines 259:0-263:23 *)
 let list_nth_mut_shared_loop_pair
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) : result (t & t) =
-  list_nth_mut_shared_loop_pair_loop t ls0 ls1 i
-
-(** [loops::list_nth_mut_shared_loop_pair]: loop 0: backward function 0
-    Source: 'src/loops.rs', lines 259:0-274:1 *)
-let rec list_nth_mut_shared_loop_pair_loop_back
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
-  Tot (result (list_t t))
-  (decreases (list_nth_mut_shared_loop_pair_loop_decreases t ls0 ls1 i))
-  =
-  begin match ls0 with
-  | List_Cons x0 tl0 ->
-    begin match ls1 with
-    | List_Cons x1 tl1 ->
-      if i = 0
-      then Return (List_Cons ret tl0)
-      else
-        let* i0 = u32_sub i 1 in
-        let* tl00 = list_nth_mut_shared_loop_pair_loop_back t tl0 tl1 i0 ret in
-        Return (List_Cons x0 tl00)
-    | List_Nil -> Fail Failure
-    end
-  | List_Nil -> Fail Failure
-  end
-
-(** [loops::list_nth_mut_shared_loop_pair]: backward function 0
-    Source: 'src/loops.rs', lines 259:0-263:23 *)
-let list_nth_mut_shared_loop_pair_back
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
-  result (list_t t)
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
+  result ((t & t) & (t -> result (list_t t)))
   =
-  list_nth_mut_shared_loop_pair_loop_back t ls0 ls1 i ret
+  let* (p, back_'a) = list_nth_mut_shared_loop_pair_loop t ls0 ls1 i in
+  let back_'a1 = fun ret -> back_'a ret in
+  Return (p, back_'a1)
 
-(** [loops::list_nth_mut_shared_loop_pair_merge]: loop 0: forward function
+(** [loops::list_nth_mut_shared_loop_pair_merge]: loop 0:
     Source: 'src/loops.rs', lines 278:0-293:1 *)
 let rec list_nth_mut_shared_loop_pair_merge_loop
   (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
-  Tot (result (t & t))
+  Tot (result ((t & t) & (t -> result (list_t t))))
   (decreases (list_nth_mut_shared_loop_pair_merge_loop_decreases t ls0 ls1 i))
   =
   begin match ls0 with
@@ -571,57 +440,36 @@ let rec list_nth_mut_shared_loop_pair_merge_loop
     begin match ls1 with
     | List_Cons x1 tl1 ->
       if i = 0
-      then Return (x0, x1)
+      then
+        let back_'a = fun ret -> Return (List_Cons ret tl0) in
+        Return ((x0, x1), back_'a)
       else
-        let* i0 = u32_sub i 1 in
-        list_nth_mut_shared_loop_pair_merge_loop t tl0 tl1 i0
+        let* i1 = u32_sub i 1 in
+        let* (p, back_'a) =
+          list_nth_mut_shared_loop_pair_merge_loop t tl0 tl1 i1 in
+        let back_'a1 =
+          fun ret -> let* tl01 = back_'a ret in Return (List_Cons x0 tl01) in
+        Return (p, back_'a1)
     | List_Nil -> Fail Failure
     end
   | List_Nil -> Fail Failure
   end
 
-(** [loops::list_nth_mut_shared_loop_pair_merge]: forward function
+(** [loops::list_nth_mut_shared_loop_pair_merge]:
     Source: 'src/loops.rs', lines 278:0-282:23 *)
 let list_nth_mut_shared_loop_pair_merge
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) : result (t & t) =
-  list_nth_mut_shared_loop_pair_merge_loop t ls0 ls1 i
-
-(** [loops::list_nth_mut_shared_loop_pair_merge]: loop 0: backward function 0
-    Source: 'src/loops.rs', lines 278:0-293:1 *)
-let rec list_nth_mut_shared_loop_pair_merge_loop_back
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
-  Tot (result (list_t t))
-  (decreases (list_nth_mut_shared_loop_pair_merge_loop_decreases t ls0 ls1 i))
-  =
-  begin match ls0 with
-  | List_Cons x0 tl0 ->
-    begin match ls1 with
-    | List_Cons x1 tl1 ->
-      if i = 0
-      then Return (List_Cons ret tl0)
-      else
-        let* i0 = u32_sub i 1 in
-        let* tl00 =
-          list_nth_mut_shared_loop_pair_merge_loop_back t tl0 tl1 i0 ret in
-        Return (List_Cons x0 tl00)
-    | List_Nil -> Fail Failure
-    end
-  | List_Nil -> Fail Failure
-  end
-
-(** [loops::list_nth_mut_shared_loop_pair_merge]: backward function 0
-    Source: 'src/loops.rs', lines 278:0-282:23 *)
-let list_nth_mut_shared_loop_pair_merge_back
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
-  result (list_t t)
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
+  result ((t & t) & (t -> result (list_t t)))
   =
-  list_nth_mut_shared_loop_pair_merge_loop_back t ls0 ls1 i ret
+  let* (p, back_'a) = list_nth_mut_shared_loop_pair_merge_loop t ls0 ls1 i in
+  let back_'a1 = fun ret -> back_'a ret in
+  Return (p, back_'a1)
 
-(** [loops::list_nth_shared_mut_loop_pair]: loop 0: forward function
+(** [loops::list_nth_shared_mut_loop_pair]: loop 0:
     Source: 'src/loops.rs', lines 297:0-312:1 *)
 let rec list_nth_shared_mut_loop_pair_loop
   (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
-  Tot (result (t & t))
+  Tot (result ((t & t) & (t -> result (list_t t))))
   (decreases (list_nth_shared_mut_loop_pair_loop_decreases t ls0 ls1 i))
   =
   begin match ls0 with
@@ -629,56 +477,35 @@ let rec list_nth_shared_mut_loop_pair_loop
     begin match ls1 with
     | List_Cons x1 tl1 ->
       if i = 0
-      then Return (x0, x1)
+      then
+        let back_'b = fun ret -> Return (List_Cons ret tl1) in
+        Return ((x0, x1), back_'b)
       else
-        let* i0 = u32_sub i 1 in
-        list_nth_shared_mut_loop_pair_loop t tl0 tl1 i0
+        let* i1 = u32_sub i 1 in
+        let* (p, back_'b) = list_nth_shared_mut_loop_pair_loop t tl0 tl1 i1 in
+        let back_'b1 =
+          fun ret -> let* tl11 = back_'b ret in Return (List_Cons x1 tl11) in
+        Return (p, back_'b1)
     | List_Nil -> Fail Failure
     end
   | List_Nil -> Fail Failure
   end
 
-(** [loops::list_nth_shared_mut_loop_pair]: forward function
+(** [loops::list_nth_shared_mut_loop_pair]:
     Source: 'src/loops.rs', lines 297:0-301:23 *)
 let list_nth_shared_mut_loop_pair
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) : result (t & t) =
-  list_nth_shared_mut_loop_pair_loop t ls0 ls1 i
-
-(** [loops::list_nth_shared_mut_loop_pair]: loop 0: backward function 1
-    Source: 'src/loops.rs', lines 297:0-312:1 *)
-let rec list_nth_shared_mut_loop_pair_loop_back
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
-  Tot (result (list_t t))
-  (decreases (list_nth_shared_mut_loop_pair_loop_decreases t ls0 ls1 i))
-  =
-  begin match ls0 with
-  | List_Cons x0 tl0 ->
-    begin match ls1 with
-    | List_Cons x1 tl1 ->
-      if i = 0
-      then Return (List_Cons ret tl1)
-      else
-        let* i0 = u32_sub i 1 in
-        let* tl10 = list_nth_shared_mut_loop_pair_loop_back t tl0 tl1 i0 ret in
-        Return (List_Cons x1 tl10)
-    | List_Nil -> Fail Failure
-    end
-  | List_Nil -> Fail Failure
-  end
-
-(** [loops::list_nth_shared_mut_loop_pair]: backward function 1
-    Source: 'src/loops.rs', lines 297:0-301:23 *)
-let list_nth_shared_mut_loop_pair_back
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
-  result (list_t t)
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
+  result ((t & t) & (t -> result (list_t t)))
   =
-  list_nth_shared_mut_loop_pair_loop_back t ls0 ls1 i ret
+  let* (p, back_'b) = list_nth_shared_mut_loop_pair_loop t ls0 ls1 i in
+  let back_'b1 = fun ret -> back_'b ret in
+  Return (p, back_'b1)
 
-(** [loops::list_nth_shared_mut_loop_pair_merge]: loop 0: forward function
+(** [loops::list_nth_shared_mut_loop_pair_merge]: loop 0:
     Source: 'src/loops.rs', lines 316:0-331:1 *)
 let rec list_nth_shared_mut_loop_pair_merge_loop
   (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
-  Tot (result (t & t))
+  Tot (result ((t & t) & (t -> result (list_t t))))
   (decreases (list_nth_shared_mut_loop_pair_merge_loop_decreases t ls0 ls1 i))
   =
   begin match ls0 with
@@ -686,49 +513,28 @@ let rec list_nth_shared_mut_loop_pair_merge_loop
     begin match ls1 with
     | List_Cons x1 tl1 ->
       if i = 0
-      then Return (x0, x1)
+      then
+        let back_'a = fun ret -> Return (List_Cons ret tl1) in
+        Return ((x0, x1), back_'a)
       else
-        let* i0 = u32_sub i 1 in
-        list_nth_shared_mut_loop_pair_merge_loop t tl0 tl1 i0
+        let* i1 = u32_sub i 1 in
+        let* (p, back_'a) =
+          list_nth_shared_mut_loop_pair_merge_loop t tl0 tl1 i1 in
+        let back_'a1 =
+          fun ret -> let* tl11 = back_'a ret in Return (List_Cons x1 tl11) in
+        Return (p, back_'a1)
     | List_Nil -> Fail Failure
     end
   | List_Nil -> Fail Failure
   end
 
-(** [loops::list_nth_shared_mut_loop_pair_merge]: forward function
+(** [loops::list_nth_shared_mut_loop_pair_merge]:
     Source: 'src/loops.rs', lines 316:0-320:23 *)
 let list_nth_shared_mut_loop_pair_merge
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) : result (t & t) =
-  list_nth_shared_mut_loop_pair_merge_loop t ls0 ls1 i
-
-(** [loops::list_nth_shared_mut_loop_pair_merge]: loop 0: backward function 0
-    Source: 'src/loops.rs', lines 316:0-331:1 *)
-let rec list_nth_shared_mut_loop_pair_merge_loop_back
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
-  Tot (result (list_t t))
-  (decreases (list_nth_shared_mut_loop_pair_merge_loop_decreases t ls0 ls1 i))
-  =
-  begin match ls0 with
-  | List_Cons x0 tl0 ->
-    begin match ls1 with
-    | List_Cons x1 tl1 ->
-      if i = 0
-      then Return (List_Cons ret tl1)
-      else
-        let* i0 = u32_sub i 1 in
-        let* tl10 =
-          list_nth_shared_mut_loop_pair_merge_loop_back t tl0 tl1 i0 ret in
-        Return (List_Cons x1 tl10)
-    | List_Nil -> Fail Failure
-    end
-  | List_Nil -> Fail Failure
-  end
-
-(** [loops::list_nth_shared_mut_loop_pair_merge]: backward function 0
-    Source: 'src/loops.rs', lines 316:0-320:23 *)
-let list_nth_shared_mut_loop_pair_merge_back
-  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) (ret : t) :
-  result (list_t t)
+  (t : Type0) (ls0 : list_t t) (ls1 : list_t t) (i : u32) :
+  result ((t & t) & (t -> result (list_t t)))
   =
-  list_nth_shared_mut_loop_pair_merge_loop_back t ls0 ls1 i ret
+  let* (p, back_'a) = list_nth_shared_mut_loop_pair_merge_loop t ls0 ls1 i in
+  let back_'a1 = fun ret -> back_'a ret in
+  Return (p, back_'a1)
 
diff --git a/tests/fstar/misc/Paper.fst b/tests/fstar/misc/Paper.fst
index 14bc59e8..c6082929 100644
--- a/tests/fstar/misc/Paper.fst
+++ b/tests/fstar/misc/Paper.fst
@@ -5,40 +5,36 @@ open Primitives
 
 #set-options "--z3rlimit 50 --fuel 1 --ifuel 1"
 
-(** [paper::ref_incr]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [paper::ref_incr]:
     Source: 'src/paper.rs', lines 4:0-4:28 *)
 let ref_incr (x : i32) : result i32 =
   i32_add x 1
 
-(** [paper::test_incr]: forward function
+(** [paper::test_incr]:
     Source: 'src/paper.rs', lines 8:0-8:18 *)
 let test_incr : result unit =
-  let* x = ref_incr 0 in if not (x = 1) then Fail Failure else Return ()
+  let* i = ref_incr 0 in if not (i = 1) then Fail Failure else Return ()
 
 (** Unit test for [paper::test_incr] *)
 let _ = assert_norm (test_incr = Return ())
 
-(** [paper::choose]: forward function
+(** [paper::choose]:
     Source: 'src/paper.rs', lines 15:0-15:70 *)
-let choose (t : Type0) (b : bool) (x : t) (y : t) : result t =
-  if b then Return x else Return y
+let choose
+  (t : Type0) (b : bool) (x : t) (y : t) : result (t & (t -> result (t & t))) =
+  if b
+  then let back_'a = fun ret -> Return (ret, y) in Return (x, back_'a)
+  else let back_'a = fun ret -> Return (x, ret) in Return (y, back_'a)
 
-(** [paper::choose]: backward function 0
-    Source: 'src/paper.rs', lines 15:0-15:70 *)
-let choose_back
-  (t : Type0) (b : bool) (x : t) (y : t) (ret : t) : result (t & t) =
-  if b then Return (ret, y) else Return (x, ret)
-
-(** [paper::test_choose]: forward function
+(** [paper::test_choose]:
     Source: 'src/paper.rs', lines 23:0-23:20 *)
 let test_choose : result unit =
-  let* z = choose i32 true 0 0 in
-  let* z0 = i32_add z 1 in
-  if not (z0 = 1)
+  let* (z, choose_back) = choose i32 true 0 0 in
+  let* z1 = i32_add z 1 in
+  if not (z1 = 1)
   then Fail Failure
   else
-    let* (x, y) = choose_back i32 true 0 0 z0 in
+    let* (x, y) = choose_back z1 in
     if not (x = 1)
     then Fail Failure
     else if not (y = 0) then Fail Failure else Return ()
@@ -52,31 +48,28 @@ type list_t (t : Type0) =
 | List_Cons : t -> list_t t -> list_t t
 | List_Nil : list_t t
 
-(** [paper::list_nth_mut]: forward function
-    Source: 'src/paper.rs', lines 42:0-42:67 *)
-let rec list_nth_mut (t : Type0) (l : list_t t) (i : u32) : result t =
-  begin match l with
-  | List_Cons x tl ->
-    if i = 0 then Return x else let* i0 = u32_sub i 1 in list_nth_mut t tl i0
-  | List_Nil -> Fail Failure
-  end
-
-(** [paper::list_nth_mut]: backward function 0
+(** [paper::list_nth_mut]:
     Source: 'src/paper.rs', lines 42:0-42:67 *)
-let rec list_nth_mut_back
-  (t : Type0) (l : list_t t) (i : u32) (ret : t) : result (list_t t) =
+let rec list_nth_mut
+  (t : Type0) (l : list_t t) (i : u32) :
+  result (t & (t -> result (list_t t)))
+  =
   begin match l with
   | List_Cons x tl ->
     if i = 0
-    then Return (List_Cons ret tl)
+    then
+      let back_'a = fun ret -> Return (List_Cons ret tl) in Return (x, back_'a)
     else
-      let* i0 = u32_sub i 1 in
-      let* tl0 = list_nth_mut_back t tl i0 ret in
-      Return (List_Cons x tl0)
+      let* i1 = u32_sub i 1 in
+      let* (x1, list_nth_mut_back) = list_nth_mut t tl i1 in
+      let back_'a =
+        fun ret -> let* tl1 = list_nth_mut_back ret in Return (List_Cons x tl1)
+        in
+      Return (x1, back_'a)
   | List_Nil -> Fail Failure
   end
 
-(** [paper::sum]: forward function
+(** [paper::sum]:
     Source: 'src/paper.rs', lines 57:0-57:32 *)
 let rec sum (l : list_t i32) : result i32 =
   begin match l with
@@ -84,27 +77,27 @@ let rec sum (l : list_t i32) : result i32 =
   | List_Nil -> Return 0
   end
 
-(** [paper::test_nth]: forward function
+(** [paper::test_nth]:
     Source: 'src/paper.rs', lines 68:0-68:17 *)
 let test_nth : result unit =
   let l = List_Nil in
-  let l0 = List_Cons 3 l in
-  let l1 = List_Cons 2 l0 in
-  let* x = list_nth_mut i32 (List_Cons 1 l1) 2 in
-  let* x0 = i32_add x 1 in
-  let* l2 = list_nth_mut_back i32 (List_Cons 1 l1) 2 x0 in
-  let* i = sum l2 in
+  let l1 = List_Cons 3 l in
+  let l2 = List_Cons 2 l1 in
+  let* (x, list_nth_mut_back) = list_nth_mut i32 (List_Cons 1 l2) 2 in
+  let* x1 = i32_add x 1 in
+  let* l3 = list_nth_mut_back x1 in
+  let* i = sum l3 in
   if not (i = 7) then Fail Failure else Return ()
 
 (** Unit test for [paper::test_nth] *)
 let _ = assert_norm (test_nth = Return ())
 
-(** [paper::call_choose]: forward function
+(** [paper::call_choose]:
     Source: 'src/paper.rs', lines 76:0-76:44 *)
 let call_choose (p : (u32 & u32)) : result u32 =
   let (px, py) = p in
-  let* pz = choose u32 true px py in
-  let* pz0 = u32_add pz 1 in
-  let* (px0, _) = choose_back u32 true px py pz0 in
-  Return px0
+  let* (pz, choose_back) = choose u32 true px py in
+  let* pz1 = u32_add pz 1 in
+  let* (px1, _) = choose_back pz1 in
+  Return px1
 
diff --git a/tests/fstar/misc/PoloniusList.fst b/tests/fstar/misc/PoloniusList.fst
index 188b22d8..cbe7d6b8 100644
--- a/tests/fstar/misc/PoloniusList.fst
+++ b/tests/fstar/misc/PoloniusList.fst
@@ -11,24 +11,24 @@ type list_t (t : Type0) =
 | List_Cons : t -> list_t t -> list_t t
 | List_Nil : list_t t
 
-(** [polonius_list::get_list_at_x]: forward function
+(** [polonius_list::get_list_at_x]:
     Source: 'src/polonius_list.rs', lines 13:0-13:76 *)
-let rec get_list_at_x (ls : list_t u32) (x : u32) : result (list_t u32) =
-  begin match ls with
-  | List_Cons hd tl ->
-    if hd = x then Return (List_Cons hd tl) else get_list_at_x tl x
-  | List_Nil -> Return List_Nil
-  end
-
-(** [polonius_list::get_list_at_x]: backward function 0
-    Source: 'src/polonius_list.rs', lines 13:0-13:76 *)
-let rec get_list_at_x_back
-  (ls : list_t u32) (x : u32) (ret : list_t u32) : result (list_t u32) =
+let rec get_list_at_x
+  (ls : list_t u32) (x : u32) :
+  result ((list_t u32) & (list_t u32 -> result (list_t u32)))
+  =
   begin match ls with
   | List_Cons hd tl ->
     if hd = x
-    then Return ret
-    else let* tl0 = get_list_at_x_back tl x ret in Return (List_Cons hd tl0)
-  | List_Nil -> Return ret
+    then
+      let back_'a = fun ret -> Return ret in Return (List_Cons hd tl, back_'a)
+    else
+      let* (l, get_list_at_x_back) = get_list_at_x tl x in
+      let back_'a =
+        fun ret ->
+          let* tl1 = get_list_at_x_back ret in Return (List_Cons hd tl1) in
+      Return (l, back_'a)
+  | List_Nil ->
+    let back_'a = fun ret -> Return ret in Return (List_Nil, back_'a)
   end
 
diff --git a/tests/fstar/misc/Primitives.fst b/tests/fstar/misc/Primitives.fst
index 6b8dbeb7..fca80829 100644
--- a/tests/fstar/misc/Primitives.fst
+++ b/tests/fstar/misc/Primitives.fst
@@ -55,7 +55,7 @@ type string = string
 let is_zero (n: nat) : bool = n = 0
 let decrease (n: nat{n > 0}) : nat = n - 1
 
-let core_mem_replace (a : Type0) (x : a) (y : a) : a & (a -> a) = (x, (fun x -> x))
+let core_mem_replace (a : Type0) (x : a) (y : a) : a & a = (x, x)
 
 // We don't really use raw pointers for now
 type mut_raw_ptr (t : Type0) = { v : t }
@@ -531,10 +531,18 @@ let array_index_usize (a : Type0) (n : usize) (x : array a n) (i : usize) : resu
   if i < length x then Return (index x i)
   else Fail Failure
 
-let array_update_usize (a : Type0) (n : usize) (x : array a n) (i : usize) (nx : a) : result (array a n) =
+let array_update_usize (a : Type0) (n : usize) (x : array a n) (i : usize) (nx : a) :
+  result (array a n) =
   if i < length x then Return (list_update x i nx)
   else Fail Failure
 
+let array_index_mut_usize (a : Type0) (n : usize) (x : array a n) (i : usize) :
+  result (a & (a -> result (array a n))) =
+  match array_index_usize a n x i with
+  | Fail e -> Fail e
+  | Return v ->
+    Return (v, array_update_usize a n x i)
+
 (*** Slice *)
 type slice (a : Type0) = s:list a{length s <= usize_max}
 
@@ -548,6 +556,13 @@ let slice_update_usize (a : Type0) (x : slice a) (i : usize) (nx : a) : result (
   if i < length x then Return (list_update x i nx)
   else Fail Failure
 
+let slice_index_mut_usize (a : Type0) (s : slice a) (i : usize) :
+  result (a & (a -> result (slice a))) =
+  match slice_index_usize a s i with
+  | Fail e -> Fail e
+  | Return x ->
+    Return (x, slice_update_usize a s i)
+
 (*** Subslices *)
 
 let array_to_slice (a : Type0) (n : usize) (x : array a n) : result (slice a) = Return x
@@ -555,6 +570,10 @@ let array_from_slice (a : Type0) (n : usize) (x : array a n) (s : slice a) : res
   if length s = n then Return s
   else Fail Failure
 
+let array_to_slice_mut (a : Type0) (n : usize) (x : array a n) :
+  result (slice a & (slice a -> result (array a n))) =
+  Return (x, array_from_slice a n x)
+
 // TODO: finish the definitions below (there lacks [List.drop] and [List.take] in the standard library *)
 let array_subslice (a : Type0) (n : usize) (x : array a n) (r : core_ops_range_Range usize) : result (slice a) =
   admit()
diff --git a/tests/fstar/traits/Primitives.fst b/tests/fstar/traits/Primitives.fst
index a3ffbde4..fca80829 100644
--- a/tests/fstar/traits/Primitives.fst
+++ b/tests/fstar/traits/Primitives.fst
@@ -55,8 +55,7 @@ type string = string
 let is_zero (n: nat) : bool = n = 0
 let decrease (n: nat{n > 0}) : nat = n - 1
 
-let core_mem_replace (a : Type0) (x : a) (y : a) : a = x
-let core_mem_replace_back (a : Type0) (x : a) (y : a) : a = y
+let core_mem_replace (a : Type0) (x : a) (y : a) : a & a = (x, x)
 
 // We don't really use raw pointers for now
 type mut_raw_ptr (t : Type0) = { v : t }
@@ -477,8 +476,7 @@ noeq type core_ops_index_Index (self idx : Type0) = {
 // Trait declaration: [core::ops::index::IndexMut]
 noeq type core_ops_index_IndexMut (self idx : Type0) = {
   indexInst : core_ops_index_Index self idx;
-  index_mut : self → idx → result indexInst.output;
-  index_mut_back : self → idx → indexInst.output → result self;
+  index_mut : self → idx → result (indexInst.output & (indexInst.output → result self));
 }
 
 // Trait declaration [core::ops::deref::Deref]
@@ -490,8 +488,7 @@ noeq type core_ops_deref_Deref (self : Type0) = {
 // Trait declaration [core::ops::deref::DerefMut]
 noeq type core_ops_deref_DerefMut (self : Type0) = {
   derefInst : core_ops_deref_Deref self;
-  deref_mut : self → result derefInst.target;
-  deref_mut_back : self → derefInst.target → result self;
+  deref_mut : self → result (derefInst.target & (derefInst.target → result self));
 }
 
 type core_ops_range_Range (a : Type0) = {
@@ -502,8 +499,8 @@ type core_ops_range_Range (a : Type0) = {
 (*** [alloc] *)
 
 let alloc_boxed_Box_deref (t : Type0) (x : t) : result t = Return x
-let alloc_boxed_Box_deref_mut (t : Type0) (x : t) : result t = Return x
-let alloc_boxed_Box_deref_mut_back (t : Type) (_ : t) (x : t) : result t = Return x
+let alloc_boxed_Box_deref_mut (t : Type0) (x : t) : result (t & (t -> result t)) =
+  Return (x, (fun x -> Return x))
 
 // Trait instance
 let alloc_boxed_Box_coreopsDerefInst (self : Type0) : core_ops_deref_Deref self = {
@@ -515,7 +512,6 @@ let alloc_boxed_Box_coreopsDerefInst (self : Type0) : core_ops_deref_Deref self
 let alloc_boxed_Box_coreopsDerefMutInst (self : Type0) : core_ops_deref_DerefMut self = {
   derefInst = alloc_boxed_Box_coreopsDerefInst self;
   deref_mut = alloc_boxed_Box_deref_mut self;
-  deref_mut_back = alloc_boxed_Box_deref_mut_back self;
 }
 
 (*** Array *)
@@ -535,10 +531,18 @@ let array_index_usize (a : Type0) (n : usize) (x : array a n) (i : usize) : resu
   if i < length x then Return (index x i)
   else Fail Failure
 
-let array_update_usize (a : Type0) (n : usize) (x : array a n) (i : usize) (nx : a) : result (array a n) =
+let array_update_usize (a : Type0) (n : usize) (x : array a n) (i : usize) (nx : a) :
+  result (array a n) =
   if i < length x then Return (list_update x i nx)
   else Fail Failure
 
+let array_index_mut_usize (a : Type0) (n : usize) (x : array a n) (i : usize) :
+  result (a & (a -> result (array a n))) =
+  match array_index_usize a n x i with
+  | Fail e -> Fail e
+  | Return v ->
+    Return (v, array_update_usize a n x i)
+
 (*** Slice *)
 type slice (a : Type0) = s:list a{length s <= usize_max}
 
@@ -552,6 +556,13 @@ let slice_update_usize (a : Type0) (x : slice a) (i : usize) (nx : a) : result (
   if i < length x then Return (list_update x i nx)
   else Fail Failure
 
+let slice_index_mut_usize (a : Type0) (s : slice a) (i : usize) :
+  result (a & (a -> result (slice a))) =
+  match slice_index_usize a s i with
+  | Fail e -> Fail e
+  | Return x ->
+    Return (x, slice_update_usize a s i)
+
 (*** Subslices *)
 
 let array_to_slice (a : Type0) (n : usize) (x : array a n) : result (slice a) = Return x
@@ -559,6 +570,10 @@ let array_from_slice (a : Type0) (n : usize) (x : array a n) (s : slice a) : res
   if length s = n then Return s
   else Fail Failure
 
+let array_to_slice_mut (a : Type0) (n : usize) (x : array a n) :
+  result (slice a & (slice a -> result (array a n))) =
+  Return (x, array_from_slice a n x)
+
 // TODO: finish the definitions below (there lacks [List.drop] and [List.take] in the standard library *)
 let array_subslice (a : Type0) (n : usize) (x : array a n) (r : core_ops_range_Range usize) : result (slice a) =
   admit()
@@ -588,8 +603,13 @@ let alloc_vec_Vec_index_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) : r
 let alloc_vec_Vec_update_usize (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
   if i < length v then Return (list_update v i x) else Fail Failure
 
-// The **forward** function shouldn't be used
-let alloc_vec_Vec_push_fwd (a  : Type0) (v : alloc_vec_Vec a) (x : a) : unit = ()
+let alloc_vec_Vec_index_mut_usize (#a : Type0) (v: alloc_vec_Vec a) (i: usize) :
+  result (a & (a → result (alloc_vec_Vec a))) =
+  match alloc_vec_Vec_index_usize v i with
+  | Return x ->
+    Return (x, alloc_vec_Vec_update_usize v i)
+  | Fail e -> Fail e
+
 let alloc_vec_Vec_push (a  : Type0) (v : alloc_vec_Vec a) (x : a) :
   Pure (result (alloc_vec_Vec a))
   (requires True)
@@ -605,9 +625,6 @@ let alloc_vec_Vec_push (a  : Type0) (v : alloc_vec_Vec a) (x : a) :
     end
   else Fail Failure
 
-// The **forward** function shouldn't be used
-let alloc_vec_Vec_insert_fwd (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result unit =
-  if i < length v then Return () else Fail Failure
 let alloc_vec_Vec_insert (a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) : result (alloc_vec_Vec a) =
   if i < length v then Return (list_update v i x) else Fail Failure
 
@@ -619,13 +636,11 @@ noeq type core_slice_index_SliceIndex (self t : Type0) = {
   sealedInst : core_slice_index_private_slice_index_Sealed self;
   output : Type0;
   get : self → t → result (option output);
-  get_mut : self → t → result (option output);
-  get_mut_back : self → t → option output → result t;
+  get_mut : self → t → result (option output & (option output -> result t));
   get_unchecked : self → const_raw_ptr t → result (const_raw_ptr output);
   get_unchecked_mut : self → mut_raw_ptr t → result (mut_raw_ptr output);
   index : self → t → result output;
-  index_mut : self → t → result output;
-  index_mut_back : self → t → output → result t;
+  index_mut : self → t → result (output & (output -> result t));
 }
 
 // [core::slice::index::[T]::index]: forward function
@@ -643,14 +658,8 @@ let core_slice_index_RangeUsize_get (t : Type0) (i : core_ops_range_Range usize)
   admit () // TODO
 
 // [core::slice::index::Range::get_mut]: forward function
-let core_slice_index_RangeUsize_get_mut
-  (t : Type0) : core_ops_range_Range usize → slice t → result (option (slice t)) =
-  admit () // TODO
-
-// [core::slice::index::Range::get_mut]: backward function 0
-let core_slice_index_RangeUsize_get_mut_back
-  (t : Type0) :
-  core_ops_range_Range usize → slice t → option (slice t) → result (slice t) =
+let core_slice_index_RangeUsize_get_mut (t : Type0) :
+  core_ops_range_Range usize → slice t → result (option (slice t) & (option (slice t) -> result (slice t))) =
   admit () // TODO
 
 // [core::slice::index::Range::get_unchecked]: forward function
@@ -675,27 +684,16 @@ let core_slice_index_RangeUsize_index
   admit () // TODO
 
 // [core::slice::index::Range::index_mut]: forward function
-let core_slice_index_RangeUsize_index_mut
-  (t : Type0) : core_ops_range_Range usize → slice t → result (slice t) =
-  admit () // TODO
-
-// [core::slice::index::Range::index_mut]: backward function 0
-let core_slice_index_RangeUsize_index_mut_back
-  (t : Type0) : core_ops_range_Range usize → slice t → slice t → result (slice t) =
+let core_slice_index_RangeUsize_index_mut (t : Type0) :
+  core_ops_range_Range usize → slice t → result (slice t & (slice t -> result (slice t))) =
   admit () // TODO
 
 // [core::slice::index::[T]::index_mut]: forward function
 let core_slice_index_Slice_index_mut
   (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
-  slice t → idx → result inst.output =
+  slice t → idx → result (inst.output & (inst.output -> result (slice t))) =
   admit () // 
 
-// [core::slice::index::[T]::index_mut]: backward function 0
-let core_slice_index_Slice_index_mut_back
-  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t)) :
-  slice t → idx → inst.output → result (slice t) =
-  admit () // TODO
-
 // [core::array::[T; N]::index]: forward function
 let core_array_Array_index
   (t idx : Type0) (n : usize) (inst : core_ops_index_Index (slice t) idx)
@@ -705,13 +703,8 @@ let core_array_Array_index
 // [core::array::[T; N]::index_mut]: forward function
 let core_array_Array_index_mut
   (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
-  (a : array t n) (i : idx) : result inst.indexInst.output =
-  admit () // TODO
-
-// [core::array::[T; N]::index_mut]: backward function 0
-let core_array_Array_index_mut_back
-  (t idx : Type0) (n : usize) (inst : core_ops_index_IndexMut (slice t) idx)
-  (a : array t n) (i : idx) (x : inst.indexInst.output) : result (array t n) =
+  (a : array t n) (i : idx) :
+  result (inst.indexInst.output & (inst.indexInst.output -> result (array t n))) =
   admit () // TODO
 
 // Trait implementation: [core::slice::index::private_slice_index::Range]
@@ -725,12 +718,10 @@ let core_slice_index_SliceIndexRangeUsizeSliceTInst (t : Type0) :
   output = slice t;
   get = core_slice_index_RangeUsize_get t;
   get_mut = core_slice_index_RangeUsize_get_mut t;
-  get_mut_back = core_slice_index_RangeUsize_get_mut_back t;
   get_unchecked = core_slice_index_RangeUsize_get_unchecked t;
   get_unchecked_mut = core_slice_index_RangeUsize_get_unchecked_mut t;
   index = core_slice_index_RangeUsize_index t;
   index_mut = core_slice_index_RangeUsize_index_mut t;
-  index_mut_back = core_slice_index_RangeUsize_index_mut_back t;
 }
 
 // Trait implementation: [core::slice::index::[T]]
@@ -747,7 +738,6 @@ let core_ops_index_IndexMutSliceTIInst (t idx : Type0)
   core_ops_index_IndexMut (slice t) idx = {
   indexInst = core_ops_index_IndexSliceTIInst t idx inst;
   index_mut = core_slice_index_Slice_index_mut t idx inst;
-  index_mut_back = core_slice_index_Slice_index_mut_back t idx inst;
 }
 
 // Trait implementation: [core::array::[T; N]]
@@ -764,7 +754,6 @@ let core_ops_index_IndexMutArrayIInst (t idx : Type0) (n : usize)
   core_ops_index_IndexMut (array t n) idx = {
   indexInst = core_ops_index_IndexArrayInst t idx n inst.indexInst;
   index_mut = core_array_Array_index_mut t idx n inst;
-  index_mut_back = core_array_Array_index_mut_back t idx n inst;
 }
 
 // [core::slice::index::usize::get]: forward function
@@ -773,13 +762,8 @@ let core_slice_index_usize_get
   admit () // TODO
 
 // [core::slice::index::usize::get_mut]: forward function
-let core_slice_index_usize_get_mut
-  (t : Type0) : usize → slice t → result (option t) =
-  admit () // TODO
-
-// [core::slice::index::usize::get_mut]: backward function 0
-let core_slice_index_usize_get_mut_back
-  (t : Type0) : usize → slice t → option t → result (slice t) =
+let core_slice_index_usize_get_mut (t : Type0) :
+  usize → slice t → result (option t & (option t -> result (slice t))) =
   admit () // TODO
 
 // [core::slice::index::usize::get_unchecked]: forward function
@@ -797,12 +781,8 @@ let core_slice_index_usize_index (t : Type0) : usize → slice t → result t =
   admit () // TODO
 
 // [core::slice::index::usize::index_mut]: forward function
-let core_slice_index_usize_index_mut (t : Type0) : usize → slice t → result t =
-  admit () // TODO
-
-// [core::slice::index::usize::index_mut]: backward function 0
-let core_slice_index_usize_index_mut_back
-  (t : Type0) : usize → slice t → t → result (slice t) =
+let core_slice_index_usize_index_mut (t : Type0) :
+  usize → slice t → result (t & (t -> result (slice t))) =
   admit () // TODO
 
 // Trait implementation: [core::slice::index::private_slice_index::usize]
@@ -816,12 +796,10 @@ let core_slice_index_SliceIndexUsizeSliceTInst (t : Type0) :
   output = t;
   get = core_slice_index_usize_get t;
   get_mut = core_slice_index_usize_get_mut t;
-  get_mut_back = core_slice_index_usize_get_mut_back t;
   get_unchecked = core_slice_index_usize_get_unchecked t;
   get_unchecked_mut = core_slice_index_usize_get_unchecked_mut t;
   index = core_slice_index_usize_index t;
   index_mut = core_slice_index_usize_index_mut t;
-  index_mut_back = core_slice_index_usize_index_mut_back t;
 }
 
 // [alloc::vec::Vec::index]: forward function
@@ -831,13 +809,8 @@ let alloc_vec_Vec_index (t idx : Type0) (inst : core_slice_index_SliceIndex idx
 
 // [alloc::vec::Vec::index_mut]: forward function
 let alloc_vec_Vec_index_mut (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
-  (self : alloc_vec_Vec t) (i : idx) : result inst.output =
-  admit () // TODO
-
-// [alloc::vec::Vec::index_mut]: backward function 0
-let alloc_vec_Vec_index_mut_back
-  (t idx : Type0) (inst : core_slice_index_SliceIndex idx (slice t))
-  (self : alloc_vec_Vec t) (i : idx) (x : inst.output) : result (alloc_vec_Vec t) =
+  (self : alloc_vec_Vec t) (i : idx) :
+  result (inst.output & (inst.output -> result (alloc_vec_Vec t))) =
   admit () // TODO
 
 // Trait implementation: [alloc::vec::Vec]
@@ -854,7 +827,6 @@ let alloc_vec_Vec_coreopsindexIndexMutInst (t idx : Type0)
   core_ops_index_IndexMut (alloc_vec_Vec t) idx = {
   indexInst = alloc_vec_Vec_coreopsindexIndexInst t idx inst;
   index_mut = alloc_vec_Vec_index_mut t idx inst;
-  index_mut_back = alloc_vec_Vec_index_mut_back t idx inst;
 }
 
 (*** Theorems *)
@@ -870,15 +842,7 @@ let alloc_vec_Vec_index_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
 let alloc_vec_Vec_index_mut_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) :
   Lemma (
     alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i ==
-      alloc_vec_Vec_index_usize v i)
+      alloc_vec_Vec_index_mut_usize v i)
   [SMTPat (alloc_vec_Vec_index_mut a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i)]
   =
   admit()
-
-let alloc_vec_Vec_index_mut_back_eq (#a : Type0) (v : alloc_vec_Vec a) (i : usize) (x : a) :
-  Lemma (
-    alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x ==
-      alloc_vec_Vec_update_usize v i x)
-  [SMTPat (alloc_vec_Vec_index_mut_back a usize (core_slice_index_SliceIndexUsizeSliceTInst a) v i x)]
-  =
-  admit()
diff --git a/tests/fstar/traits/Traits.fst b/tests/fstar/traits/Traits.fst
index 7d504cb5..3543bd73 100644
--- a/tests/fstar/traits/Traits.fst
+++ b/tests/fstar/traits/Traits.fst
@@ -9,7 +9,7 @@ open Primitives
     Source: 'src/traits.rs', lines 1:0-1:19 *)
 noeq type boolTrait_t (self : Type0) = { get_bool : self -> result bool; }
 
-(** [traits::{bool}::get_bool]: forward function
+(** [traits::{bool}::get_bool]:
     Source: 'src/traits.rs', lines 12:4-12:30 *)
 let bool_get_bool (self : bool) : result bool =
   Return self
@@ -18,24 +18,24 @@ let bool_get_bool (self : bool) : result bool =
     Source: 'src/traits.rs', lines 11:0-11:23 *)
 let traits_BoolTraitBoolInst : boolTrait_t bool = { get_bool = bool_get_bool; }
 
-(** [traits::BoolTrait::ret_true]: forward function
+(** [traits::BoolTrait::ret_true]:
     Source: 'src/traits.rs', lines 6:4-6:30 *)
 let boolTrait_ret_true
-  (#self : Type0) (self_clause : boolTrait_t self) (self0 : self) :
+  (#self : Type0) (self_clause : boolTrait_t self) (self1 : self) :
   result bool
   =
   Return true
 
-(** [traits::test_bool_trait_bool]: forward function
+(** [traits::test_bool_trait_bool]:
     Source: 'src/traits.rs', lines 17:0-17:44 *)
 let test_bool_trait_bool (x : bool) : result bool =
   let* b = bool_get_bool x in
   if b then boolTrait_ret_true traits_BoolTraitBoolInst x else Return false
 
-(** [traits::{core::option::Option<T>#1}::get_bool]: forward function
+(** [traits::{core::option::Option<T>#1}::get_bool]:
     Source: 'src/traits.rs', lines 23:4-23:30 *)
 let option_get_bool (t : Type0) (self : option t) : result bool =
-  begin match self with | None -> Return false | Some x -> Return true end
+  begin match self with | None -> Return false | Some _ -> Return true end
 
 (** Trait implementation: [traits::{core::option::Option<T>#1}]
     Source: 'src/traits.rs', lines 22:0-22:31 *)
@@ -44,7 +44,7 @@ let traits_BoolTraitcoreoptionOptionTInst (t : Type0) : boolTrait_t (option t)
   get_bool = option_get_bool t;
 }
 
-(** [traits::test_bool_trait_option]: forward function
+(** [traits::test_bool_trait_option]:
     Source: 'src/traits.rs', lines 31:0-31:54 *)
 let test_bool_trait_option (t : Type0) (x : option t) : result bool =
   let* b = option_get_bool t x in
@@ -52,7 +52,7 @@ let test_bool_trait_option (t : Type0) (x : option t) : result bool =
   then boolTrait_ret_true (traits_BoolTraitcoreoptionOptionTInst t) x
   else Return false
 
-(** [traits::test_bool_trait]: forward function
+(** [traits::test_bool_trait]:
     Source: 'src/traits.rs', lines 35:0-35:50 *)
 let test_bool_trait
   (t : Type0) (boolTraitTInst : boolTrait_t t) (x : t) : result bool =
@@ -62,7 +62,7 @@ let test_bool_trait
     Source: 'src/traits.rs', lines 39:0-39:15 *)
 noeq type toU64_t (self : Type0) = { to_u64 : self -> result u64; }
 
-(** [traits::{u64#2}::to_u64]: forward function
+(** [traits::{u64#2}::to_u64]:
     Source: 'src/traits.rs', lines 44:4-44:26 *)
 let u64_to_u64 (self : u64) : result u64 =
   Return self
@@ -71,14 +71,14 @@ let u64_to_u64 (self : u64) : result u64 =
     Source: 'src/traits.rs', lines 43:0-43:18 *)
 let traits_ToU64U64Inst : toU64_t u64 = { to_u64 = u64_to_u64; }
 
-(** [traits::{(A, A)#3}::to_u64]: forward function
+(** [traits::{(A, A)#3}::to_u64]:
     Source: 'src/traits.rs', lines 50:4-50:26 *)
 let pair_to_u64
   (a : Type0) (toU64AInst : toU64_t a) (self : (a & a)) : result u64 =
-  let (x, x0) = self in
+  let (x, x1) = self in
   let* i = toU64AInst.to_u64 x in
-  let* i0 = toU64AInst.to_u64 x0 in
-  u64_add i i0
+  let* i1 = toU64AInst.to_u64 x1 in
+  u64_add i i1
 
 (** Trait implementation: [traits::{(A, A)#3}]
     Source: 'src/traits.rs', lines 49:0-49:31 *)
@@ -87,18 +87,18 @@ let traits_ToU64TupleAAInst (a : Type0) (toU64AInst : toU64_t a) : toU64_t (a &
   to_u64 = pair_to_u64 a toU64AInst;
 }
 
-(** [traits::f]: forward function
+(** [traits::f]:
     Source: 'src/traits.rs', lines 55:0-55:36 *)
 let f (t : Type0) (toU64TInst : toU64_t t) (x : (t & t)) : result u64 =
   pair_to_u64 t toU64TInst x
 
-(** [traits::g]: forward function
+(** [traits::g]:
     Source: 'src/traits.rs', lines 59:0-61:18 *)
 let g
   (t : Type0) (toU64TupleTTInst : toU64_t (t & t)) (x : (t & t)) : result u64 =
   toU64TupleTTInst.to_u64 x
 
-(** [traits::h0]: forward function
+(** [traits::h0]:
     Source: 'src/traits.rs', lines 66:0-66:24 *)
 let h0 (x : u64) : result u64 =
   u64_to_u64 x
@@ -107,7 +107,7 @@ let h0 (x : u64) : result u64 =
     Source: 'src/traits.rs', lines 70:0-70:21 *)
 type wrapper_t (t : Type0) = { x : t; }
 
-(** [traits::{traits::Wrapper<T>#4}::to_u64]: forward function
+(** [traits::{traits::Wrapper<T>#4}::to_u64]:
     Source: 'src/traits.rs', lines 75:4-75:26 *)
 let wrapper_to_u64
   (t : Type0) (toU64TInst : toU64_t t) (self : wrapper_t t) : result u64 =
@@ -120,12 +120,12 @@ let traits_ToU64traitsWrapperTInst (t : Type0) (toU64TInst : toU64_t t) :
   to_u64 = wrapper_to_u64 t toU64TInst;
 }
 
-(** [traits::h1]: forward function
+(** [traits::h1]:
     Source: 'src/traits.rs', lines 80:0-80:33 *)
 let h1 (x : wrapper_t u64) : result u64 =
   wrapper_to_u64 u64 traits_ToU64U64Inst x
 
-(** [traits::h2]: forward function
+(** [traits::h2]:
     Source: 'src/traits.rs', lines 84:0-84:41 *)
 let h2 (t : Type0) (toU64TInst : toU64_t t) (x : wrapper_t t) : result u64 =
   wrapper_to_u64 t toU64TInst x
@@ -134,7 +134,7 @@ let h2 (t : Type0) (toU64TInst : toU64_t t) (x : wrapper_t t) : result u64 =
     Source: 'src/traits.rs', lines 88:0-88:19 *)
 noeq type toType_t (self t : Type0) = { to_type : self -> result t; }
 
-(** [traits::{u64#5}::to_type]: forward function
+(** [traits::{u64#5}::to_type]:
     Source: 'src/traits.rs', lines 93:4-93:28 *)
 let u64_to_type (self : u64) : result bool =
   Return (self > 0)
@@ -150,7 +150,7 @@ noeq type ofType_t (self : Type0) = {
     self;
 }
 
-(** [traits::h3]: forward function
+(** [traits::h3]:
     Source: 'src/traits.rs', lines 104:0-104:50 *)
 let h3
   (t1 t2 : Type0) (ofTypeT1Inst : ofType_t t1) (toTypeT2T1Inst : toType_t t2
@@ -166,7 +166,7 @@ noeq type ofTypeBis_t (self t : Type0) = {
   of_type : t -> result self;
 }
 
-(** [traits::h4]: forward function
+(** [traits::h4]:
     Source: 'src/traits.rs', lines 118:0-118:57 *)
 let h4
   (t1 t2 : Type0) (ofTypeBisT1T2Inst : ofTypeBis_t t1 t2) (toTypeT2T1Inst :
@@ -189,7 +189,7 @@ noeq type testType_test_TestTrait_t (self : Type0) = {
   test : self -> result bool;
 }
 
-(** [traits::{traits::TestType<T>#6}::test::{traits::{traits::TestType<T>#6}::test::TestType1}::test]: forward function
+(** [traits::{traits::TestType<T>#6}::test::{traits::{traits::TestType<T>#6}::test::TestType1}::test]:
     Source: 'src/traits.rs', lines 139:12-139:34 *)
 let testType_test_TestType1_test
   (self : testType_test_TestType1_t) : result bool =
@@ -202,20 +202,20 @@ let traits_TestType_test_TestTraittraitstraitsTestTypeTtestTestType1Inst :
   test = testType_test_TestType1_test;
 }
 
-(** [traits::{traits::TestType<T>#6}::test]: forward function
+(** [traits::{traits::TestType<T>#6}::test]:
     Source: 'src/traits.rs', lines 126:4-126:36 *)
 let testType_test
   (t : Type0) (toU64TInst : toU64_t t) (self : testType_t t) (x : t) :
   result bool
   =
-  let* x0 = toU64TInst.to_u64 x in
-  if x0 > 0 then testType_test_TestType1_test 0 else Return false
+  let* x1 = toU64TInst.to_u64 x in
+  if x1 > 0 then testType_test_TestType1_test 0 else Return false
 
 (** [traits::BoolWrapper]
     Source: 'src/traits.rs', lines 150:0-150:22 *)
 type boolWrapper_t = bool
 
-(** [traits::{traits::BoolWrapper#7}::to_type]: forward function
+(** [traits::{traits::BoolWrapper#7}::to_type]:
     Source: 'src/traits.rs', lines 156:4-156:25 *)
 let boolWrapper_to_type
   (t : Type0) (toTypeBoolTInst : toType_t bool t) (self : boolWrapper_t) :
@@ -251,8 +251,7 @@ noeq type withConstTy_t (self : Type0) (len : usize) = {
 let bool_len1_body : result usize = Return 12
 let bool_len1_c : usize = eval_global bool_len1_body
 
-(** [traits::{bool#8}::f]: merged forward/backward function
-    (there is a single backward function, and the forward function returns ())
+(** [traits::{bool#8}::f]:
     Source: 'src/traits.rs', lines 180:4-180:39 *)
 let bool_f (i : u64) (a : array u8 32) : result u64 =
   Return i
@@ -268,7 +267,7 @@ let traits_WithConstTyBool32Inst : withConstTy_t bool 32 = {
   f = bool_f;
 }
 
-(** [traits::use_with_const_ty1]: forward function
+(** [traits::use_with_const_ty1]:
     Source: 'src/traits.rs', lines 183:0-183:75 *)
 let use_with_const_ty1
   (h : Type0) (len : usize) (withConstTyHLENInst : withConstTy_t h len) :
@@ -276,7 +275,7 @@ let use_with_const_ty1
   =
   let i = withConstTyHLENInst.cLEN1 in Return i
 
-(** [traits::use_with_const_ty2]: forward function
+(** [traits::use_with_const_ty2]:
     Source: 'src/traits.rs', lines 187:0-187:73 *)
 let use_with_const_ty2
   (h : Type0) (len : usize) (withConstTyHLENInst : withConstTy_t h len)
@@ -285,7 +284,7 @@ let use_with_const_ty2
   =
   Return ()
 
-(** [traits::use_with_const_ty3]: forward function
+(** [traits::use_with_const_ty3]:
     Source: 'src/traits.rs', lines 189:0-189:80 *)
 let use_with_const_ty3
   (h : Type0) (len : usize) (withConstTyHLENInst : withConstTy_t h len)
@@ -294,12 +293,12 @@ let use_with_const_ty3
   =
   withConstTyHLENInst.tW_clause_0.to_u64 x
 
-(** [traits::test_where1]: forward function
+(** [traits::test_where1]:
     Source: 'src/traits.rs', lines 193:0-193:40 *)
 let test_where1 (t : Type0) (_x : t) : result unit =
   Return ()
 
-(** [traits::test_where2]: forward function
+(** [traits::test_where2]:
     Source: 'src/traits.rs', lines 194:0-194:57 *)
 let test_where2
   (t : Type0) (withConstTyT32Inst : withConstTy_t t 32) (_x : u32) :
@@ -326,22 +325,30 @@ noeq type childTrait_t (self : Type0) = {
   parentTrait1SelfInst : parentTrait1_t self;
 }
 
-(** [traits::test_child_trait1]: forward function
-    Source: 'src/traits.rs', lines 209:0-209:56 *)
+(** [traits::test_parent_trait0]:
+    Source: 'src/traits.rs', lines 208:0-208:57 *)
+let test_parent_trait0
+  (t : Type0) (parentTrait0TInst : parentTrait0_t t) (x : t) :
+  result parentTrait0TInst.tW
+  =
+  parentTrait0TInst.get_w x
+
+(** [traits::test_child_trait1]:
+    Source: 'src/traits.rs', lines 213:0-213:56 *)
 let test_child_trait1
   (t : Type0) (childTraitTInst : childTrait_t t) (x : t) : result string =
   childTraitTInst.parentTrait0SelfInst.get_name x
 
-(** [traits::test_child_trait2]: forward function
-    Source: 'src/traits.rs', lines 213:0-213:54 *)
+(** [traits::test_child_trait2]:
+    Source: 'src/traits.rs', lines 217:0-217:54 *)
 let test_child_trait2
   (t : Type0) (childTraitTInst : childTrait_t t) (x : t) :
   result childTraitTInst.parentTrait0SelfInst.tW
   =
   childTraitTInst.parentTrait0SelfInst.get_w x
 
-(** [traits::order1]: forward function
-    Source: 'src/traits.rs', lines 219:0-219:59 *)
+(** [traits::order1]:
+    Source: 'src/traits.rs', lines 223:0-223:59 *)
 let order1
   (t u : Type0) (parentTrait0TInst : parentTrait0_t t) (parentTrait0UInst :
   parentTrait0_t u) :
@@ -350,27 +357,27 @@ let order1
   Return ()
 
 (** Trait declaration: [traits::ChildTrait1]
-    Source: 'src/traits.rs', lines 222:0-222:35 *)
+    Source: 'src/traits.rs', lines 226:0-226:35 *)
 noeq type childTrait1_t (self : Type0) = {
   parentTrait1SelfInst : parentTrait1_t self;
 }
 
 (** Trait implementation: [traits::{usize#9}]
-    Source: 'src/traits.rs', lines 224:0-224:27 *)
+    Source: 'src/traits.rs', lines 228:0-228:27 *)
 let traits_ParentTrait1UsizeInst : parentTrait1_t usize = ()
 
 (** Trait implementation: [traits::{usize#10}]
-    Source: 'src/traits.rs', lines 225:0-225:26 *)
+    Source: 'src/traits.rs', lines 229:0-229:26 *)
 let traits_ChildTrait1UsizeInst : childTrait1_t usize = {
   parentTrait1SelfInst = traits_ParentTrait1UsizeInst;
 }
 
 (** Trait declaration: [traits::Iterator]
-    Source: 'src/traits.rs', lines 229:0-229:18 *)
+    Source: 'src/traits.rs', lines 233:0-233:18 *)
 noeq type iterator_t (self : Type0) = { tItem : Type0; }
 
 (** Trait declaration: [traits::IntoIterator]
-    Source: 'src/traits.rs', lines 233:0-233:22 *)
+    Source: 'src/traits.rs', lines 237:0-237:22 *)
 noeq type intoIterator_t (self : Type0) = {
   tItem : Type0;
   tIntoIter : Type0;
@@ -379,29 +386,29 @@ noeq type intoIterator_t (self : Type0) = {
 }
 
 (** Trait declaration: [traits::FromResidual]
-    Source: 'src/traits.rs', lines 250:0-250:21 *)
+    Source: 'src/traits.rs', lines 254:0-254:21 *)
 type fromResidual_t (self t : Type0) = unit
 
 (** Trait declaration: [traits::Try]
-    Source: 'src/traits.rs', lines 246:0-246:48 *)
+    Source: 'src/traits.rs', lines 250:0-250:48 *)
 noeq type try_t (self : Type0) = {
   tResidual : Type0;
   fromResidualSelftraitsTrySelfResidualInst : fromResidual_t self tResidual;
 }
 
 (** Trait declaration: [traits::WithTarget]
-    Source: 'src/traits.rs', lines 252:0-252:20 *)
+    Source: 'src/traits.rs', lines 256:0-256:20 *)
 noeq type withTarget_t (self : Type0) = { tTarget : Type0; }
 
 (** Trait declaration: [traits::ParentTrait2]
-    Source: 'src/traits.rs', lines 256:0-256:22 *)
+    Source: 'src/traits.rs', lines 260:0-260:22 *)
 noeq type parentTrait2_t (self : Type0) = {
   tU : Type0;
   tU_clause_0 : withTarget_t tU;
 }
 
 (** Trait declaration: [traits::ChildTrait2]
-    Source: 'src/traits.rs', lines 260:0-260:35 *)
+    Source: 'src/traits.rs', lines 264:0-264:35 *)
 noeq type childTrait2_t (self : Type0) = {
   parentTrait2SelfInst : parentTrait2_t self;
   convert : parentTrait2SelfInst.tU -> result
@@ -409,48 +416,59 @@ noeq type childTrait2_t (self : Type0) = {
 }
 
 (** Trait implementation: [traits::{u32#11}]
-    Source: 'src/traits.rs', lines 264:0-264:23 *)
+    Source: 'src/traits.rs', lines 268:0-268:23 *)
 let traits_WithTargetU32Inst : withTarget_t u32 = { tTarget = u32; }
 
 (** Trait implementation: [traits::{u32#12}]
-    Source: 'src/traits.rs', lines 268:0-268:25 *)
+    Source: 'src/traits.rs', lines 272:0-272:25 *)
 let traits_ParentTrait2U32Inst : parentTrait2_t u32 = {
   tU = u32;
   tU_clause_0 = traits_WithTargetU32Inst;
 }
 
-(** [traits::{u32#13}::convert]: forward function
-    Source: 'src/traits.rs', lines 273:4-273:29 *)
+(** [traits::{u32#13}::convert]:
+    Source: 'src/traits.rs', lines 277:4-277:29 *)
 let u32_convert (x : u32) : result u32 =
   Return x
 
 (** Trait implementation: [traits::{u32#13}]
-    Source: 'src/traits.rs', lines 272:0-272:24 *)
+    Source: 'src/traits.rs', lines 276:0-276:24 *)
 let traits_ChildTrait2U32Inst : childTrait2_t u32 = {
   parentTrait2SelfInst = traits_ParentTrait2U32Inst;
   convert = u32_convert;
 }
 
 (** Trait declaration: [traits::CFnOnce]
-    Source: 'src/traits.rs', lines 286:0-286:23 *)
+    Source: 'src/traits.rs', lines 290:0-290:23 *)
 noeq type cFnOnce_t (self args : Type0) = {
   tOutput : Type0;
   call_once : self -> args -> result tOutput;
 }
 
 (** Trait declaration: [traits::CFnMut]
-    Source: 'src/traits.rs', lines 292:0-292:37 *)
+    Source: 'src/traits.rs', lines 296:0-296:37 *)
 noeq type cFnMut_t (self args : Type0) = {
   cFnOnceSelfArgsInst : cFnOnce_t self args;
-  call_mut : self -> args -> result cFnOnceSelfArgsInst.tOutput;
-  call_mut_back : self -> args -> cFnOnceSelfArgsInst.tOutput -> result self;
+  call_mut : self -> args -> result (cFnOnceSelfArgsInst.tOutput & self);
 }
 
 (** Trait declaration: [traits::CFn]
-    Source: 'src/traits.rs', lines 296:0-296:33 *)
+    Source: 'src/traits.rs', lines 300:0-300:33 *)
 noeq type cFn_t (self args : Type0) = {
   cFnMutSelfArgsInst : cFnMut_t self args;
-  call_mut : self -> args -> result
-    cFnMutSelfArgsInst.cFnOnceSelfArgsInst.tOutput;
+  call : self -> args -> result cFnMutSelfArgsInst.cFnOnceSelfArgsInst.tOutput;
+}
+
+(** Trait declaration: [traits::GetTrait]
+    Source: 'src/traits.rs', lines 304:0-304:18 *)
+noeq type getTrait_t (self : Type0) = { tW : Type0; get_w : self -> result tW;
 }
 
+(** [traits::test_get_trait]:
+    Source: 'src/traits.rs', lines 309:0-309:49 *)
+let test_get_trait
+  (t : Type0) (getTraitTInst : getTrait_t t) (x : t) :
+  result getTraitTInst.tW
+  =
+  getTraitTInst.get_w x
+