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-rw-r--r--backends/lean/primitives.lean16
1 files changed, 9 insertions, 7 deletions
diff --git a/backends/lean/primitives.lean b/backends/lean/primitives.lean
index d86c0423..9e72b708 100644
--- a/backends/lean/primitives.lean
+++ b/backends/lean/primitives.lean
@@ -131,26 +131,28 @@ macro_rules
def vec (α : Type u) := { l : List α // List.length l < USize.size }
-def vec_new : result (vec α) := return ⟨ [], by {
+def vec_new (α : Type u): result (vec α) := return ⟨ [], by {
match USize.size, usize_size_eq with
| _, Or.inl rfl => simp
| _, Or.inr rfl => simp
} ⟩
-def vec_len (v : vec α) : USize :=
+#check vec_new
+
+def vec_len (α : Type u) (v : vec α) : USize :=
let ⟨ v, l ⟩ := v
USize.ofNatCore (List.length v) l
#eval do
- return (vec_len (<- @vec_new Nat))
+ return (vec_len Nat (<- vec_new Nat))
-def vec_push_fwd (_ : vec α) (_ : α) : Unit := ()
+def vec_push_fwd (α : Type u) (_ : vec α) (_ : α) : Unit := ()
-- TODO: more precise error condition here for the fail case
-- TODO: I originally wrote `List.length v.val < USize.size - 1`; how can one
-- make the proof work in that case? Probably need to import tactics from
-- mathlib to deal with inequalities... would love to see an example.
-def vec_push_back (v : vec α) (x : α) : { res: result (vec α) //
+def vec_push_back (α : Type u) (v : vec α) (x : α) : { res: result (vec α) //
match res with | fail _ => True | ret v' => List.length v'.val = List.length v.val + 1}
:=
if h : List.length v.val + 1 < USize.size then
@@ -168,7 +170,7 @@ def vec_push_back (v : vec α) (x : α) : { res: result (vec α) //
-- select the `val` field if the context provides a type annotation. We
-- annotate `x`, which relieves us of having to write `.val` on the right-hand
-- side of the monadic let.
- let x: vec Nat ← vec_push_back (<- vec_new) 1
+ let x: vec Nat ← vec_push_back Nat (<- vec_new Nat) 1
-- TODO: strengthen post-condition above and do a demo to show that we can
-- safely eliminate the `fail` case
- return (vec_len x)
+ return (vec_len Nat x)