Use more local modules.

demos/brz/Brzozowski.ml

@@ -270,10 +270,8 @@ let neg (e : regexp) : regexp =
 
 (* We memoize this function. (This is optional.) *)
 
-module M =
-  Memoize.ForHashedType(R)
-
 let nullable : regexp -> bool =
+  let module M = Memoize.ForHashedType(R) in
   M.fix (fun nullable e ->
     match skeleton e with
     | EChar _ ->
@@ -303,12 +301,10 @@ let nullable : regexp -> bool =
    star.) More precisely, for every character [a], [delta a] is a function of
    type [regexp -> regexp]: we memoize every function [delta a] separately. *)
 
-(* A tabulator for functions of type [char -> _] is used for this purpose. *)
-
-module T =
-  Tabulate.ForHashedType(Char)(Char)
 
 let delta : Char.t -> regexp -> regexp =
+  let module T = Tabulate.ForHashedType(Char)(Char) in
+  let module M = Memoize.ForHashedType(R) in
   T.tabulate (fun a ->
     M.fix (fun delta e ->
       match skeleton e with
@@ -430,6 +426,7 @@ let dfa (e : regexp) : dfa =
   (* There remains to tabulate the transition function. *)
   let transition =
     let module Q = Tabulate.ForIntSegment(N) in
+    let module T = Tabulate.ForHashedType(Char)(Char) in
     Q.tabulate (fun q -> T.tabulate (fun a ->
       encode (delta a (decode q))
     ))