feat(gs/achilles): Implement very basic monomorphization r/2296

Implement very basic monomorphization, by recording type variable
instantiations when typechecking Call nodes and then using those in a
new hir Visitor trait to copy the body of any generic decls for each
possible set of instantiation of the type variables.

Change-Id: Iab54030973e5d66e2b8bcd074b4cb6c001a90123
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2617
Reviewed-by: glittershark <grfn@gws.fyi>
Tested-by: BuildkiteCI

1 files changed, 6 insertions, 1 deletions

diff --git a/users/glittershark/achilles/src/interpreter/mod.rs b/users/glittershark/achilles/src/interpreter/mod.rs
index 3bfeeb52e85c..bcd474b3abe1 100644
--- a/users/glittershark/achilles/src/interpreter/mod.rs
+++ b/users/glittershark/achilles/src/interpreter/mod.rs
@@ -96,7 +96,12 @@ impl<'a> Interpreter<'a> {
                 }
                 Ok(Value::from(*interpreter.eval(body)?.as_type::<i64>()?))
             }
-            Expr::Fun { args, body, type_ } => {
+            Expr::Fun {
+                type_args: _,
+                args,
+                body,
+                type_,
+            } => {
                 let type_ = match type_ {
                     Type::Function(ft) => ft.clone(),
                     _ => unreachable!("Function expression without function type"),