From 32fac8c22454186aa6327474e63cde99958e3d4b Mon Sep 17 00:00:00 2001
From: Son Ho
Date: Fri, 28 Jan 2022 15:10:40 +0100
Subject: Implement the unit_vars_to_unit pass

---
 src/PureMicroPasses.ml | 26 +++++++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

(limited to 'src')

diff --git a/src/PureMicroPasses.ml b/src/PureMicroPasses.ml
index b3e65055..c75d9f9b 100644
--- a/src/PureMicroPasses.ml
+++ b/src/PureMicroPasses.ml
@@ -336,10 +336,30 @@ let to_monadic (def : fun_def) : fun_def =
   { def with signature }
 
 (** Convert the unit variables to `()` if they are used as right-values or
-    `_` if they are used as left values. *)
+    `_` if they are used as left values in patterns. *)
 let unit_vars_to_unit (def : fun_def) : fun_def =
-  (* TODO *)
-  def
+  (* The map visitor *)
+  let obj =
+    object
+      inherit [_] map_expression as super
+
+      method! visit_var_or_dummy _ v =
+        match v with
+        | Dummy -> Dummy
+        | Var (v, mp) -> if v.ty = unit_ty then Dummy else Var (v, mp)
+      (** Replace in lvalues *)
+
+      method! visit_typed_rvalue env rv =
+        if rv.ty = unit_ty then unit_rvalue else super#visit_typed_rvalue env rv
+      (** Replace in rvalues *)
+    end
+  in
+  (* Update the body *)
+  let body = obj#visit_expression () def.body in
+  (* Update the input parameters *)
+  let inputs_lvs = List.map (obj#visit_typed_lvalue ()) def.inputs_lvs in
+  (* Return *)
+  { def with body; inputs_lvs }
 
 (** Apply all the micro-passes to a function.
 
-- 
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