(* Title: ZF/Coind/Language.thy
Author: Jacob Frost, Cambridge University Computer Laboratory
Copyright 1995 University of Cambridge
*)
theory Language imports Main begin
text{*these really can't be definitions without losing the abstraction*}
axiomatization
Const :: i and (* Abstract type of constants *)
c_app :: "[i,i] => i" (* Abstract constructor for fun application*)
where
constNEE: "c \<in> Const ==> c \<noteq> 0" and
c_appI: "[| c1 \<in> Const; c2 \<in> Const |] ==> c_app(c1,c2) \<in> Const"
consts
Exp :: i (* Datatype of expressions *)
ExVar :: i (* Abstract type of variables *)
datatype
"Exp" = e_const ("c \<in> Const")
| e_var ("x \<in> ExVar")
| e_fn ("x \<in> ExVar","e \<in> Exp")
| e_fix ("x1 \<in> ExVar","x2 \<in> ExVar","e \<in> Exp")
| e_app ("e1 \<in> Exp","e2 \<in> Exp")
end