Code back-end: type annotations for values extracted out of the stack.

CHANGES

+2016/03/11:
+In the code back-end, generate type annotations when extracting a semantic
+value out of the stack. When working with a semantic value of some function
+type, OCaml would incorrectly warn that this function does not use its
+argument. This warning should now be gone.
+
 2016/03/03:
 Makefile changes, so as to support ocamlbuild 4.03, which seems to have
 stricter hygiene rules than previous versions.

src/codeBackend.ml

@@ -715,10 +715,14 @@ let runcellparams var holds_state symbol =
 let reducecellparams prod i holds_state symbol =
   let ids = Production.identifiers prod in
 
-  (* The semantic value is bound to the variable [ids.(i)]. *)
-
-  let semvpat _t =
-    PVar ids.(i)
+  (* The semantic value is bound to the variable [ids.(i)]. Its type is [t]. As
+     of 2016/03/11, we generate a type annotation. Indeed, because of our use of
+     [magic], the semantic value would otherwise have an unknown type; and, if
+     it is a function, the OCaml compiler could warn (incorrectly) that this
+     function does not use its argument. *)
+
+  let semvpat t =
+    PAnnot (PVar ids.(i), t)
   in
 
   elementif (Invariant.endp symbol) (PVar (Printf.sprintf "_endpos_%s_" ids.(i))) @