Merge pull request #64 from AeneasVerif/son/merge_back

Merge the forward/backward functions

1 files changed, 231 insertions, 264 deletions

diff --git a/tests/lean/Array.lean b/tests/lean/Array.lean
index 25dad3cf..7785a208 100644
--- a/tests/lean/Array.lean
+++ b/tests/lean/Array.lean
@@ -11,99 +11,91 @@ inductive AB :=
 | A : AB
 | B : AB
 
-/- [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 -/
 def incr (x : U32) : Result U32 :=
   x + 1#u32
 
-/- [array::array_to_shared_slice_]: forward function
+/- [array::array_to_shared_slice_]:
    Source: 'src/array.rs', lines 16:0-16:53 -/
 def array_to_shared_slice_
   (T : Type) (s : Array T 32#usize) : Result (Slice T) :=
   Array.to_slice T 32#usize s
 
-/- [array::array_to_mut_slice_]: forward function
+/- [array::array_to_mut_slice_]:
    Source: 'src/array.rs', lines 21:0-21:58 -/
-def array_to_mut_slice_ (T : Type) (s : Array T 32#usize) : Result (Slice T) :=
-  Array.to_slice T 32#usize s
-
-/- [array::array_to_mut_slice_]: backward function 0
-   Source: 'src/array.rs', lines 21:0-21:58 -/
-def array_to_mut_slice__back
-  (T : Type) (s : Array T 32#usize) (ret : Slice T) :
-  Result (Array T 32#usize)
+def array_to_mut_slice_
+  (T : Type) (s : Array T 32#usize) :
+  Result ((Slice T) × (Slice T → Result (Array T 32#usize)))
   :=
-  Array.from_slice T 32#usize s ret
+  do
+  let (s1, to_slice_mut_back) ← Array.to_slice_mut T 32#usize s
+  Result.ret (s1, to_slice_mut_back)
 
-/- [array::array_len]: forward function
+/- [array::array_len]:
    Source: 'src/array.rs', lines 25:0-25:40 -/
 def array_len (T : Type) (s : Array T 32#usize) : Result Usize :=
   do
-    let s0 ← Array.to_slice T 32#usize s
-    let i := Slice.len T s0
-    Result.ret i
+  let s1 ← Array.to_slice T 32#usize s
+  let i := Slice.len T s1
+  Result.ret i
 
-/- [array::shared_array_len]: forward function
+/- [array::shared_array_len]:
    Source: 'src/array.rs', lines 29:0-29:48 -/
 def shared_array_len (T : Type) (s : Array T 32#usize) : Result Usize :=
   do
-    let s0 ← Array.to_slice T 32#usize s
-    let i := Slice.len T s0
-    Result.ret i
+  let s1 ← Array.to_slice T 32#usize s
+  let i := Slice.len T s1
+  Result.ret i
 
-/- [array::shared_slice_len]: forward function
+/- [array::shared_slice_len]:
    Source: 'src/array.rs', lines 33:0-33:44 -/
 def shared_slice_len (T : Type) (s : Slice T) : Result Usize :=
   let i := Slice.len T s
   Result.ret i
 
-/- [array::index_array_shared]: forward function
+/- [array::index_array_shared]:
    Source: 'src/array.rs', lines 37:0-37:57 -/
 def index_array_shared
   (T : Type) (s : Array T 32#usize) (i : Usize) : Result T :=
   Array.index_usize T 32#usize s i
 
-/- [array::index_array_u32]: forward function
+/- [array::index_array_u32]:
    Source: 'src/array.rs', lines 44:0-44:53 -/
 def index_array_u32 (s : Array U32 32#usize) (i : Usize) : Result U32 :=
   Array.index_usize U32 32#usize s i
 
-/- [array::index_array_copy]: forward function
+/- [array::index_array_copy]:
    Source: 'src/array.rs', lines 48:0-48:45 -/
 def index_array_copy (x : Array U32 32#usize) : Result U32 :=
   Array.index_usize U32 32#usize x 0#usize
 
-/- [array::index_mut_array]: forward function
+/- [array::index_mut_array]:
    Source: 'src/array.rs', lines 52:0-52:62 -/
-def index_mut_array (T : Type) (s : Array T 32#usize) (i : Usize) : Result T :=
-  Array.index_usize T 32#usize s i
-
-/- [array::index_mut_array]: backward function 0
-   Source: 'src/array.rs', lines 52:0-52:62 -/
-def index_mut_array_back
-  (T : Type) (s : Array T 32#usize) (i : Usize) (ret : T) :
-  Result (Array T 32#usize)
+def index_mut_array
+  (T : Type) (s : Array T 32#usize) (i : Usize) :
+  Result (T × (T → Result (Array T 32#usize)))
   :=
-  Array.update_usize T 32#usize s i ret
+  do
+  let (t, index_mut_back) ← Array.index_mut_usize T 32#usize s i
+  Result.ret (t, index_mut_back)
 
-/- [array::index_slice]: forward function
+/- [array::index_slice]:
    Source: 'src/array.rs', lines 56:0-56:46 -/
 def index_slice (T : Type) (s : Slice T) (i : Usize) : Result T :=
   Slice.index_usize T s i
 
-/- [array::index_mut_slice]: forward function
+/- [array::index_mut_slice]:
    Source: 'src/array.rs', lines 60:0-60:58 -/
-def index_mut_slice (T : Type) (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 -/
-def index_mut_slice_back
-  (T : Type) (s : Slice T) (i : Usize) (ret : T) : Result (Slice T) :=
-  Slice.update_usize T s i ret
+def index_mut_slice
+  (T : Type) (s : Slice T) (i : Usize) :
+  Result (T × (T → Result (Slice T)))
+  :=
+  do
+  let (t, index_mut_back) ← Slice.index_mut_usize T s i
+  Result.ret (t, index_mut_back)
 
-/- [array::slice_subslice_shared_]: forward function
+/- [array::slice_subslice_shared_]:
    Source: 'src/array.rs', lines 64:0-64:70 -/
 def slice_subslice_shared_
   (x : Slice U32) (y : Usize) (z : Usize) : Result (Slice U32) :=
@@ -111,41 +103,35 @@ def 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 -/
 def 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 -/
-def 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
+  do
+  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 }
+  Result.ret (s, index_mut_back)
 
-/- [array::array_to_slice_shared_]: forward function
+/- [array::array_to_slice_shared_]:
    Source: 'src/array.rs', lines 72:0-72:54 -/
 def array_to_slice_shared_ (x : Array U32 32#usize) : Result (Slice U32) :=
   Array.to_slice U32 32#usize x
 
-/- [array::array_to_slice_mut_]: forward function
+/- [array::array_to_slice_mut_]:
    Source: 'src/array.rs', lines 76:0-76:59 -/
-def array_to_slice_mut_ (x : Array U32 32#usize) : Result (Slice U32) :=
-  Array.to_slice U32 32#usize x
-
-/- [array::array_to_slice_mut_]: backward function 0
-   Source: 'src/array.rs', lines 76:0-76:59 -/
-def array_to_slice_mut__back
-  (x : Array U32 32#usize) (ret : Slice U32) : Result (Array U32 32#usize) :=
-  Array.from_slice U32 32#usize x ret
+def array_to_slice_mut_
+  (x : Array U32 32#usize) :
+  Result ((Slice U32) × (Slice U32 → Result (Array U32 32#usize)))
+  :=
+  do
+  let (s, to_slice_mut_back) ← Array.to_slice_mut U32 32#usize x
+  Result.ret (s, to_slice_mut_back)
 
-/- [array::array_subslice_shared_]: forward function
+/- [array::array_subslice_shared_]:
    Source: 'src/array.rs', lines 80:0-80:74 -/
 def array_subslice_shared_
   (x : Array U32 32#usize) (y : Usize) (z : Usize) : Result (Slice U32) :=
@@ -154,311 +140,294 @@ def 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 -/
 def array_subslice_mut_
-  (x : Array U32 32#usize) (y : Usize) (z : Usize) : Result (Slice U32) :=
-  core.array.Array.index_mut U32 (core.ops.range.Range Usize) 32#usize
-    (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 -/
-def array_subslice_mut__back
-  (x : Array U32 32#usize) (y : Usize) (z : Usize) (ret : Slice U32) :
-  Result (Array U32 32#usize)
+  (x : Array U32 32#usize) (y : Usize) (z : Usize) :
+  Result ((Slice U32) × (Slice U32 → Result (Array U32 32#usize)))
   :=
-  core.array.Array.index_mut_back U32 (core.ops.range.Range Usize) 32#usize
-    (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
+  do
+  let (s, index_mut_back) ←
+    core.array.Array.index_mut U32 (core.ops.range.Range Usize) 32#usize
+      (core.ops.index.IndexMutSliceTIInst U32 (core.ops.range.Range Usize)
+      (core.slice.index.SliceIndexRangeUsizeSliceTInst U32)) x
+      { start := y, end_ := z }
+  Result.ret (s, index_mut_back)
+
+/- [array::index_slice_0]:
    Source: 'src/array.rs', lines 88:0-88:38 -/
 def index_slice_0 (T : Type) (s : Slice T) : Result T :=
   Slice.index_usize T s 0#usize
 
-/- [array::index_array_0]: forward function
+/- [array::index_array_0]:
    Source: 'src/array.rs', lines 92:0-92:42 -/
 def index_array_0 (T : Type) (s : Array T 32#usize) : Result T :=
   Array.index_usize T 32#usize s 0#usize
 
-/- [array::index_index_array]: forward function
+/- [array::index_index_array]:
    Source: 'src/array.rs', lines 103:0-103:71 -/
 def index_index_array
   (s : Array (Array U32 32#usize) 32#usize) (i : Usize) (j : Usize) :
   Result U32
   :=
   do
-    let a ← Array.index_usize (Array U32 32#usize) 32#usize s i
-    Array.index_usize U32 32#usize a j
+  let a ← Array.index_usize (Array U32 32#usize) 32#usize s i
+  Array.index_usize U32 32#usize a j
 
-/- [array::update_update_array]: forward function
+/- [array::update_update_array]:
    Source: 'src/array.rs', lines 114:0-114:70 -/
 def update_update_array
   (s : Array (Array U32 32#usize) 32#usize) (i : Usize) (j : Usize) :
   Result Unit
   :=
   do
-    let a ← Array.index_usize (Array U32 32#usize) 32#usize s i
-    let a0 ← Array.update_usize U32 32#usize a j 0#u32
-    let _ ← Array.update_usize (Array U32 32#usize) 32#usize s i a0
-    Result.ret ()
+  let (a, index_mut_back) ←
+    Array.index_mut_usize (Array U32 32#usize) 32#usize s i
+  let (_, index_mut_back1) ← Array.index_mut_usize U32 32#usize a j
+  let a1 ← index_mut_back1 0#u32
+  let _ ← index_mut_back a1
+  Result.ret ()
 
-/- [array::array_local_deep_copy]: forward function
+/- [array::array_local_deep_copy]:
    Source: 'src/array.rs', lines 118:0-118:43 -/
 def array_local_deep_copy (x : Array U32 32#usize) : Result Unit :=
   Result.ret ()
 
-/- [array::take_array]: forward function
+/- [array::take_array]:
    Source: 'src/array.rs', lines 122:0-122:30 -/
 def take_array (a : Array U32 2#usize) : Result Unit :=
   Result.ret ()
 
-/- [array::take_array_borrow]: forward function
+/- [array::take_array_borrow]:
    Source: 'src/array.rs', lines 123:0-123:38 -/
 def take_array_borrow (a : Array U32 2#usize) : Result Unit :=
   Result.ret ()
 
-/- [array::take_slice]: forward function
+/- [array::take_slice]:
    Source: 'src/array.rs', lines 124:0-124:28 -/
 def take_slice (s : Slice U32) : Result Unit :=
   Result.ret ()
 
-/- [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 -/
 def take_mut_slice (s : Slice U32) : Result (Slice U32) :=
   Result.ret s
 
-/- [array::const_array]: forward function
+/- [array::const_array]:
    Source: 'src/array.rs', lines 127:0-127:32 -/
 def const_array : Result (Array U32 2#usize) :=
   Result.ret (Array.make U32 2#usize [ 0#u32, 0#u32 ])
 
-/- [array::const_slice]: forward function
+/- [array::const_slice]:
    Source: 'src/array.rs', lines 131:0-131:20 -/
 def const_slice : Result Unit :=
   do
-    let _ ←
-      Array.to_slice U32 2#usize (Array.make U32 2#usize [ 0#u32, 0#u32 ])
-    Result.ret ()
+  let _ ←
+    Array.to_slice U32 2#usize (Array.make U32 2#usize [ 0#u32, 0#u32 ])
+  Result.ret ()
 
-/- [array::take_all]: forward function
+/- [array::take_all]:
    Source: 'src/array.rs', lines 141:0-141:17 -/
 def take_all : Result Unit :=
   do
-    let _ ← take_array (Array.make U32 2#usize [ 0#u32, 0#u32 ])
-    let _ ← take_array_borrow (Array.make U32 2#usize [ 0#u32, 0#u32 ])
-    let s ←
-      Array.to_slice U32 2#usize (Array.make U32 2#usize [ 0#u32, 0#u32 ])
-    let _ ← take_slice s
-    let s0 ←
-      Array.to_slice U32 2#usize (Array.make U32 2#usize [ 0#u32, 0#u32 ])
-    let s1 ← take_mut_slice s0
-    let _ ←
-      Array.from_slice U32 2#usize (Array.make U32 2#usize [ 0#u32, 0#u32 ]) s1
-    Result.ret ()
-
-/- [array::index_array]: forward function
+  let _ ← take_array (Array.make U32 2#usize [ 0#u32, 0#u32 ])
+  let _ ← take_array (Array.make U32 2#usize [ 0#u32, 0#u32 ])
+  let _ ← take_array_borrow (Array.make U32 2#usize [ 0#u32, 0#u32 ])
+  let s ←
+    Array.to_slice U32 2#usize (Array.make U32 2#usize [ 0#u32, 0#u32 ])
+  let _ ← take_slice s
+  let (s1, to_slice_mut_back) ←
+    Array.to_slice_mut U32 2#usize (Array.make U32 2#usize [ 0#u32, 0#u32 ])
+  let s2 ← take_mut_slice s1
+  let _ ← to_slice_mut_back s2
+  Result.ret ()
+
+/- [array::index_array]:
    Source: 'src/array.rs', lines 155:0-155:38 -/
 def index_array (x : Array U32 2#usize) : Result U32 :=
   Array.index_usize U32 2#usize x 0#usize
 
-/- [array::index_array_borrow]: forward function
+/- [array::index_array_borrow]:
    Source: 'src/array.rs', lines 158:0-158:46 -/
 def index_array_borrow (x : Array U32 2#usize) : Result U32 :=
   Array.index_usize U32 2#usize x 0#usize
 
-/- [array::index_slice_u32_0]: forward function
+/- [array::index_slice_u32_0]:
    Source: 'src/array.rs', lines 162:0-162:42 -/
 def index_slice_u32_0 (x : Slice U32) : Result U32 :=
   Slice.index_usize U32 x 0#usize
 
-/- [array::index_mut_slice_u32_0]: forward function
+/- [array::index_mut_slice_u32_0]:
    Source: 'src/array.rs', lines 166:0-166:50 -/
-def index_mut_slice_u32_0 (x : Slice U32) : Result U32 :=
-  Slice.index_usize U32 x 0#usize
-
-/- [array::index_mut_slice_u32_0]: backward function 0
-   Source: 'src/array.rs', lines 166:0-166:50 -/
-def index_mut_slice_u32_0_back (x : Slice U32) : Result (Slice U32) :=
+def index_mut_slice_u32_0 (x : Slice U32) : Result (U32 × (Slice U32)) :=
   do
-    let _ ← Slice.index_usize U32 x 0#usize
-    Result.ret x
+  let i ← Slice.index_usize U32 x 0#usize
+  Result.ret (i, x)
 
-/- [array::index_all]: forward function
+/- [array::index_all]:
    Source: 'src/array.rs', lines 170:0-170:25 -/
 def index_all : Result U32 :=
   do
-    let i ← index_array (Array.make U32 2#usize [ 0#u32, 0#u32 ])
-    let i0 ← index_array (Array.make U32 2#usize [ 0#u32, 0#u32 ])
-    let i1 ← i + i0
-    let i2 ← index_array_borrow (Array.make U32 2#usize [ 0#u32, 0#u32 ])
-    let i3 ← i1 + i2
-    let s ←
-      Array.to_slice U32 2#usize (Array.make U32 2#usize [ 0#u32, 0#u32 ])
-    let i4 ← index_slice_u32_0 s
-    let i5 ← i3 + i4
-    let s0 ←
-      Array.to_slice U32 2#usize (Array.make U32 2#usize [ 0#u32, 0#u32 ])
-    let i6 ← index_mut_slice_u32_0 s0
-    let i7 ← i5 + i6
-    let s1 ← index_mut_slice_u32_0_back s0
-    let _ ←
-      Array.from_slice U32 2#usize (Array.make U32 2#usize [ 0#u32, 0#u32 ]) s1
-    Result.ret i7
-
-/- [array::update_array]: forward function
+  let i ← index_array (Array.make U32 2#usize [ 0#u32, 0#u32 ])
+  let i1 ← index_array (Array.make U32 2#usize [ 0#u32, 0#u32 ])
+  let i2 ← i + i1
+  let i3 ← index_array_borrow (Array.make U32 2#usize [ 0#u32, 0#u32 ])
+  let i4 ← i2 + i3
+  let s ←
+    Array.to_slice U32 2#usize (Array.make U32 2#usize [ 0#u32, 0#u32 ])
+  let i5 ← index_slice_u32_0 s
+  let i6 ← i4 + i5
+  let (s1, to_slice_mut_back) ←
+    Array.to_slice_mut U32 2#usize (Array.make U32 2#usize [ 0#u32, 0#u32 ])
+  let (i7, s2) ← index_mut_slice_u32_0 s1
+  let i8 ← i6 + i7
+  let _ ← to_slice_mut_back s2
+  Result.ret i8
+
+/- [array::update_array]:
    Source: 'src/array.rs', lines 184:0-184:36 -/
 def update_array (x : Array U32 2#usize) : Result Unit :=
   do
-    let _ ← Array.update_usize U32 2#usize x 0#usize 1#u32
-    Result.ret ()
+  let (_, index_mut_back) ← Array.index_mut_usize U32 2#usize x 0#usize
+  let _ ← index_mut_back 1#u32
+  Result.ret ()
 
-/- [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 -/
 def update_array_mut_borrow
   (x : Array U32 2#usize) : Result (Array U32 2#usize) :=
-  Array.update_usize U32 2#usize x 0#usize 1#u32
+  do
+  let (_, index_mut_back) ← Array.index_mut_usize U32 2#usize x 0#usize
+  index_mut_back 1#u32
 
-/- [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 -/
 def update_mut_slice (x : Slice U32) : Result (Slice U32) :=
-  Slice.update_usize U32 x 0#usize 1#u32
+  do
+  let (_, index_mut_back) ← Slice.index_mut_usize U32 x 0#usize
+  index_mut_back 1#u32
 
-/- [array::update_all]: forward function
+/- [array::update_all]:
    Source: 'src/array.rs', lines 194:0-194:19 -/
 def update_all : Result Unit :=
   do
-    let _ ← update_array (Array.make U32 2#usize [ 0#u32, 0#u32 ])
-    let x ← update_array_mut_borrow (Array.make U32 2#usize [ 0#u32, 0#u32 ])
-    let s ← Array.to_slice U32 2#usize x
-    let s0 ← update_mut_slice s
-    let _ ← Array.from_slice U32 2#usize x s0
-    Result.ret ()
-
-/- [array::range_all]: forward function
+  let _ ← update_array (Array.make U32 2#usize [ 0#u32, 0#u32 ])
+  let _ ← update_array (Array.make U32 2#usize [ 0#u32, 0#u32 ])
+  let a ← update_array_mut_borrow (Array.make U32 2#usize [ 0#u32, 0#u32 ])
+  let (s, to_slice_mut_back) ← Array.to_slice_mut U32 2#usize a
+  let s1 ← update_mut_slice s
+  let _ ← to_slice_mut_back s1
+  Result.ret ()
+
+/- [array::range_all]:
    Source: 'src/array.rs', lines 205:0-205:18 -/
 def range_all : Result Unit :=
   do
-    let s ←
-      core.array.Array.index_mut U32 (core.ops.range.Range Usize) 4#usize
-        (core.ops.index.IndexMutSliceTIInst U32 (core.ops.range.Range Usize)
-        (core.slice.index.SliceIndexRangeUsizeSliceTInst U32))
-        (Array.make U32 4#usize [ 0#u32, 0#u32, 0#u32, 0#u32 ])
-        { start := 1#usize, end_ := 3#usize }
-    let s0 ← update_mut_slice s
-    let _ ←
-      core.array.Array.index_mut_back U32 (core.ops.range.Range Usize) 4#usize
-        (core.ops.index.IndexMutSliceTIInst U32 (core.ops.range.Range Usize)
-        (core.slice.index.SliceIndexRangeUsizeSliceTInst U32))
-        (Array.make U32 4#usize [ 0#u32, 0#u32, 0#u32, 0#u32 ])
-        { start := 1#usize, end_ := 3#usize } s0
-    Result.ret ()
-
-/- [array::deref_array_borrow]: forward function
+  let (s, index_mut_back) ←
+    core.array.Array.index_mut U32 (core.ops.range.Range Usize) 4#usize
+      (core.ops.index.IndexMutSliceTIInst U32 (core.ops.range.Range Usize)
+      (core.slice.index.SliceIndexRangeUsizeSliceTInst U32))
+      (Array.make U32 4#usize [ 0#u32, 0#u32, 0#u32, 0#u32 ])
+      { start := 1#usize, end_ := 3#usize }
+  let s1 ← update_mut_slice s
+  let _ ← index_mut_back s1
+  Result.ret ()
+
+/- [array::deref_array_borrow]:
    Source: 'src/array.rs', lines 214:0-214:46 -/
 def deref_array_borrow (x : Array U32 2#usize) : Result U32 :=
   Array.index_usize U32 2#usize x 0#usize
 
-/- [array::deref_array_mut_borrow]: forward function
-   Source: 'src/array.rs', lines 219:0-219:54 -/
-def deref_array_mut_borrow (x : Array U32 2#usize) : Result U32 :=
-  Array.index_usize U32 2#usize x 0#usize
-
-/- [array::deref_array_mut_borrow]: backward function 0
+/- [array::deref_array_mut_borrow]:
    Source: 'src/array.rs', lines 219:0-219:54 -/
-def deref_array_mut_borrow_back
-  (x : Array U32 2#usize) : Result (Array U32 2#usize) :=
+def deref_array_mut_borrow
+  (x : Array U32 2#usize) : Result (U32 × (Array U32 2#usize)) :=
   do
-    let _ ← Array.index_usize U32 2#usize x 0#usize
-    Result.ret x
+  let i ← Array.index_usize U32 2#usize x 0#usize
+  Result.ret (i, x)
 
-/- [array::take_array_t]: forward function
+/- [array::take_array_t]:
    Source: 'src/array.rs', lines 227:0-227:31 -/
 def take_array_t (a : Array AB 2#usize) : Result Unit :=
   Result.ret ()
 
-/- [array::non_copyable_array]: forward function
+/- [array::non_copyable_array]:
    Source: 'src/array.rs', lines 229:0-229:27 -/
 def non_copyable_array : Result Unit :=
   do
-    let _ ← take_array_t (Array.make AB 2#usize [ AB.A, AB.B ])
-    Result.ret ()
+  let _ ← take_array_t (Array.make AB 2#usize [ AB.A, AB.B ])
+  Result.ret ()
 
-/- [array::sum]: loop 0: forward function
+/- [array::sum]: loop 0:
    Source: 'src/array.rs', lines 242:0-250:1 -/
-divergent def sum_loop (s : Slice U32) (sum0 : U32) (i : Usize) : Result U32 :=
-  let i0 := Slice.len U32 s
-  if i < i0
+divergent def sum_loop (s : Slice U32) (sum1 : U32) (i : Usize) : Result U32 :=
+  let i1 := Slice.len U32 s
+  if i < i1
   then
     do
-      let i1 ← Slice.index_usize U32 s i
-      let sum1 ← sum0 + i1
-      let i2 ← i + 1#usize
-      sum_loop s sum1 i2
-  else Result.ret sum0
+    let i2 ← Slice.index_usize U32 s i
+    let sum3 ← sum1 + i2
+    let i3 ← i + 1#usize
+    sum_loop s sum3 i3
+  else Result.ret sum1
 
-/- [array::sum]: forward function
+/- [array::sum]:
    Source: 'src/array.rs', lines 242:0-242:28 -/
 def sum (s : Slice U32) : Result U32 :=
   sum_loop s 0#u32 0#usize
 
-/- [array::sum2]: loop 0: forward function
+/- [array::sum2]: loop 0:
    Source: 'src/array.rs', lines 252:0-261:1 -/
 divergent def sum2_loop
-  (s : Slice U32) (s2 : Slice U32) (sum0 : U32) (i : Usize) : Result U32 :=
-  let i0 := Slice.len U32 s
-  if i < i0
+  (s : Slice U32) (s2 : Slice U32) (sum1 : U32) (i : Usize) : Result U32 :=
+  let i1 := Slice.len U32 s
+  if i < i1
   then
     do
-      let i1 ← Slice.index_usize U32 s i
-      let i2 ← Slice.index_usize U32 s2 i
-      let i3 ← i1 + i2
-      let sum1 ← sum0 + i3
-      let i4 ← i + 1#usize
-      sum2_loop s s2 sum1 i4
-  else Result.ret sum0
-
-/- [array::sum2]: forward function
+    let i2 ← Slice.index_usize U32 s i
+    let i3 ← Slice.index_usize U32 s2 i
+    let i4 ← i2 + i3
+    let sum3 ← sum1 + i4
+    let i5 ← i + 1#usize
+    sum2_loop s s2 sum3 i5
+  else Result.ret sum1
+
+/- [array::sum2]:
    Source: 'src/array.rs', lines 252:0-252:41 -/
 def sum2 (s : Slice U32) (s2 : Slice U32) : Result U32 :=
   let i := Slice.len U32 s
-  let i0 := Slice.len U32 s2
-  if not (i = i0)
+  let i1 := Slice.len U32 s2
+  if not (i = i1)
   then Result.fail .panic
   else sum2_loop s s2 0#u32 0#usize
 
-/- [array::f0]: forward function
+/- [array::f0]:
    Source: 'src/array.rs', lines 263:0-263:11 -/
 def f0 : Result Unit :=
   do
-    let s ←
-      Array.to_slice U32 2#usize (Array.make U32 2#usize [ 1#u32, 2#u32 ])
-    let s0 ← Slice.update_usize U32 s 0#usize 1#u32
-    let _ ←
-      Array.from_slice U32 2#usize (Array.make U32 2#usize [ 1#u32, 2#u32 ]) s0
-    Result.ret ()
-
-/- [array::f1]: forward function
+  let (s, to_slice_mut_back) ←
+    Array.to_slice_mut U32 2#usize (Array.make U32 2#usize [ 1#u32, 2#u32 ])
+  let (_, index_mut_back) ← Slice.index_mut_usize U32 s 0#usize
+  let s1 ← index_mut_back 1#u32
+  let _ ← to_slice_mut_back s1
+  Result.ret ()
+
+/- [array::f1]:
    Source: 'src/array.rs', lines 268:0-268:11 -/
 def f1 : Result Unit :=
   do
-    let _ ←
-      Array.update_usize U32 2#usize (Array.make U32 2#usize [ 1#u32, 2#u32 ])
-        0#usize 1#u32
-    Result.ret ()
+  let (_, index_mut_back) ←
+    Array.index_mut_usize U32 2#usize (Array.make U32 2#usize [ 1#u32, 2#u32 ])
+      0#usize
+  let _ ← index_mut_back 1#u32
+  Result.ret ()
 
-/- [array::f2]: forward function
+/- [array::f2]:
    Source: 'src/array.rs', lines 273:0-273:17 -/
 def f2 (i : U32) : Result Unit :=
   Result.ret ()
 
-/- [array::f4]: forward function
+/- [array::f4]:
    Source: 'src/array.rs', lines 282:0-282:54 -/
 def f4 (x : Array U32 32#usize) (y : Usize) (z : Usize) : Result (Slice U32) :=
   core.array.Array.index U32 (core.ops.range.Range Usize) 32#usize
@@ -466,44 +435,42 @@ def f4 (x : Array U32 32#usize) (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 -/
 def f3 : Result U32 :=
   do
-    let i ←
-      Array.index_usize U32 2#usize (Array.make U32 2#usize [ 1#u32, 2#u32 ])
-        0#usize
-    let _ ← f2 i
-    let b := Array.repeat U32 32#usize 0#u32
-    let s ←
-      Array.to_slice U32 2#usize (Array.make U32 2#usize [ 1#u32, 2#u32 ])
-    let s0 ← f4 b 16#usize 18#usize
-    sum2 s s0
+  let i ←
+    Array.index_usize U32 2#usize (Array.make U32 2#usize [ 1#u32, 2#u32 ])
+      0#usize
+  let _ ← f2 i
+  let b := Array.repeat U32 32#usize 0#u32
+  let s ←
+    Array.to_slice U32 2#usize (Array.make U32 2#usize [ 1#u32, 2#u32 ])
+  let s1 ← f4 b 16#usize 18#usize
+  sum2 s s1
 
 /- [array::SZ]
    Source: 'src/array.rs', lines 286:0-286:19 -/
 def sz_body : Result Usize := Result.ret 32#usize
 def sz_c : Usize := eval_global sz_body (by simp)
 
-/- [array::f5]: forward function
+/- [array::f5]:
    Source: 'src/array.rs', lines 289:0-289:31 -/
 def f5 (x : Array U32 32#usize) : Result U32 :=
   Array.index_usize U32 32#usize x 0#usize
 
-/- [array::ite]: forward function
+/- [array::ite]:
    Source: 'src/array.rs', lines 294:0-294:12 -/
 def ite : Result Unit :=
   do
-    let s ←
-      Array.to_slice U32 2#usize (Array.make U32 2#usize [ 0#u32, 0#u32 ])
-    let s0 ←
-      Array.to_slice U32 2#usize (Array.make U32 2#usize [ 0#u32, 0#u32 ])
-    let s1 ← index_mut_slice_u32_0_back s0
-    let _ ←
-      Array.from_slice U32 2#usize (Array.make U32 2#usize [ 0#u32, 0#u32 ]) s1
-    let s2 ← index_mut_slice_u32_0_back s
-    let _ ←
-      Array.from_slice U32 2#usize (Array.make U32 2#usize [ 0#u32, 0#u32 ]) s2
-    Result.ret ()
+  let (s, to_slice_mut_back) ←
+    Array.to_slice_mut U32 2#usize (Array.make U32 2#usize [ 0#u32, 0#u32 ])
+  let (_, s1) ← index_mut_slice_u32_0 s
+  let (s2, to_slice_mut_back1) ←
+    Array.to_slice_mut U32 2#usize (Array.make U32 2#usize [ 0#u32, 0#u32 ])
+  let (_, s3) ← index_mut_slice_u32_0 s2
+  let _ ← to_slice_mut_back1 s3
+  let _ ← to_slice_mut_back s1
+  Result.ret ()
 
 end array