(* 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