(* Title: TFL/mask
ID: $Id$
Author: Konrad Slind, Cambridge University Computer Laboratory
Copyright 1997 University of Cambridge
*)
(*---------------------------------------------------------------------------
* This structure is intended to shield TFL from any constructors already
* declared in the environment. In the Isabelle port, for example, there
* was already a datatype with "|->" being a constructor. In TFL we were
* trying to define a function "|->", but it failed in PolyML (which conforms
* better to the Standard) while the definition was accepted in NJ/SML
* (which doesn't always conform so well to the standard).
*---------------------------------------------------------------------------*)
structure Mask : Mask_sig =
struct
datatype 'a binding = |-> of ('a * 'a) (* infix 7 |->; *)
datatype mask = ERR
end;