src/ZF/Coind/Types.thy

fixed dots;

(*  Title:      ZF/Coind/Types.thy
    ID:         $Id$
    Author:     Jacob Frost, Cambridge University Computer Laboratory
    Copyright   1995  University of Cambridge
*)

Types = Language +

consts
  Ty :: i                       (* Datatype of types *)
  TyConst :: i          (* Abstract type of type constants *)
datatype <= "univ(TyConst)"
  "Ty" = t_const("tc:TyConst")
       | t_fun("t1:Ty","t2:Ty")
  

(* Definition of type environments and associated operators *)

consts
  TyEnv :: i
datatype <= "univ(Ty Un ExVar)"
  "TyEnv" = te_emp
          | te_owr("te:TyEnv","x:ExVar","t:Ty") 

consts
  te_rec :: [i,i,[i,i,i,i]=>i] => i
defs
  te_rec_def
    "te_rec(te,c,h) ==   
    Vrec(te,%te g. TyEnv_case(c,%tem x t. h(tem,x,t,g`tem),te))"
  
consts
  te_dom :: i => i
  te_app :: [i,i] => i
defs
  te_dom_def "te_dom(te) == te_rec(te,0,% te x t r. r Un {x})"
  te_app_def "te_app(te,x) == te_rec(te,0, % te y t r. if(x=y,t,r))"
  

end