Fix use type of last expression in a sequence

[tiger.ml.git] / compiler / src / lib / tiger / tiger_semant.ml

diff --git a/compiler/src/lib/tiger/tiger_semant.ml b/compiler/src/lib/tiger/tiger_semant.ml
index a0fdf3d..70639e9 100644 (file)
--- a/compiler/src/lib/tiger/tiger_semant.ml
+++ b/compiler/src/lib/tiger/tiger_semant.ml
@@ -19,18 +19,19 @@ module Semant : sig
    * Appel's
    *)
   val transExp : env:Env.t -> A.exp -> expty
-  val transVar : env:Env.t -> A.var -> expty
-  val transDec : env:Env.t -> A.dec -> Env.t
-  val transTy  : env:Env.t -> A.ty  -> Type.t  (* needs only type env *)
+
+  (* transVar does not seem to be needed, as trvar handles all our cases.
+   * Am I wrong?
+   *
+   * val transVar : env:Env.t -> A.var -> expty
+   *
+   *)
 end = struct
   type expty =
     { exp : Translate.exp
     ; ty  : Type.t
     }
 
-  let unimplemented () =
-    failwith "unimplemented"
-
   let return ty     = {exp = (); ty}
   let return_unit   = return Type.Unit
   let return_nil    = return Type.Nil
@@ -99,12 +100,18 @@ end = struct
               E.raise (E.Wrong_type_used_as_record {ty_id=typ; ty; pos})
             );
           return ty
-      | A.SeqExp exps ->
-          (* Ignoring value because we only care if a type-checking exception
-           * is raised in one of trexp calls: *)
-          List.iter exps ~f:(fun (exp, _) -> ignore (trexp exp));
-          (* FIXME: Return type of last expression, not unit. *)
+      | A.SeqExp [] ->
           return_unit
+      | A.SeqExp exps ->
+          let last xs =
+            xs
+            |> List.rev  (* Yes, redundant, but clean-looking ;-P *)
+            |> List.hd   (* Empty is matched in above SeqExp match case *)
+          in
+          exps
+          |> List.map ~f:(fun (exp, _) -> let {ty; _} = trexp exp in ty)
+          |> last
+          |> return
       | A.AssignExp {var; exp; pos} ->
           check_same (trvar var) (trexp exp) ~pos;
           (* TODO: Add var->exp to val env? *)
@@ -131,7 +138,8 @@ end = struct
           check_int (trexp lo) ~pos;
           check_int (trexp hi) ~pos;
           (* Only care if a type-error is raised *)
-          ignore (transExp ~env:(Env.set_typ env var Type.Int) body);
+          let env = Env.set_val env var (Value.Var {ty = Type.Int}) in
+          ignore (transExp ~env body);
           return_unit
       | A.BreakExp _ ->
           return_unit
@@ -235,7 +243,7 @@ end = struct
       )
     in
     trexp exp
-  and transDec ~env dec =
+  and transDec ~(env : Env.t) (dec : A.dec) : Env.t =
     (match dec with
     | A.VarDec {name; typ=typ_opt; init; pos=pos_outter; escape=_} ->
         let ty =
@@ -279,7 +287,7 @@ end = struct
             Env.set_val env name (Value.Fun {formals; result})
         )
     )
-  and transTy ~env typ =
+  and transTy ~(env : Env.t) (typ : A.ty) : Type.t =
     (match typ with
     | A.NameTy {symbol=sym; pos} ->
         env_get_typ ~sym ~env ~pos
@@ -295,16 +303,6 @@ end = struct
         let element_ty = env_get_typ ~sym ~env ~pos in
         Type.new_array element_ty
     )
-
-  let transVar ~env:_ var =
-    (match var with
-    | A.SimpleVar {symbol=_; _} ->
-        unimplemented ()
-    | A.FieldVar {var=_; symbol=_; _} ->
-        unimplemented ()
-    | A.SubscriptVar {var=_; exp=_; _} ->
-        unimplemented ()
-    )
 end
 
 open Semant