Change [Infer.ntvar] to return a type, not a string. Do not export...

Change [Infer.ntvar] to return a type, not a string. Do not export [CodePieces.ntvar], which is unused.

src/codePieces.ml

@@ -87,7 +87,7 @@ let semvtypent nt =
          can't happen. However, running type inference is only an
          option, so we still have to deal with that case. *)
 
-      TypVar (ntvar nt)
+      ntvar nt
 
   | Some ocamltype ->
 

src/codePieces.mli

@@ -22,10 +22,6 @@ open Grammar
 
 (* Naming conventions. *)
 
-(* The type variable associated with a nonterminal [nt]. *)
-
-val ntvar : Nonterminal.t -> string
-
 (* The variable that holds the environment. This is a parameter to all
    functions. We do not make it a global variable because we wish to
    preserve re-entrancy. *)

src/infer.ml

@@ -26,7 +26,7 @@ open TokenType
    cannot clash with OCaml keywords. *)
 
 let ntvar symbol =
-  Printf.sprintf "tv_%s" (Misc.normalize symbol)
+  TypVar (Printf.sprintf "tv_%s" (Misc.normalize symbol))
 
 (* The term variable associated with a nonterminal symbol. Its name begins
    with a prefix which ensures that it begins with a lowercase letter and
@@ -73,7 +73,7 @@ let nttype grammar nt =
    try
      TypTextual (StringMap.find nt grammar.types)
    with Not_found ->
-     TypVar (ntvar nt)
+     ntvar nt
 
 (* [is_standard] determines whether a branch derives from a standard
    library definition. The method, based on a file name, is somewhat

src/infer.mli

@@ -16,7 +16,7 @@ open BasicSyntax
 (* [ntvar symbol] is the name of the type variable associated with a
    nonterminal symbol. *)
 
-val ntvar: string -> string
+val ntvar: string -> IL.typ
 
 (* [infer grammar] analyzes the grammar [grammar] and returns a new
    grammar, augmented with a [%type] declaration for every nonterminal