Theory Values

theory Values
imports Language Map
(*  Title:      ZF/Coind/Values.thy
Author: Jacob Frost, Cambridge University Computer Laboratory
Copyright 1995 University of Cambridge
*)


theory Values imports Language Map begin

(* Values, values environments and associated operators *)

consts
Val :: i
ValEnv :: i
Val_ValEnv :: i;

codatatype
"Val" = v_const ("c ∈ Const")
| v_clos ("x ∈ ExVar","e ∈ Exp","ve ∈ ValEnv")
and
"ValEnv" = ve_mk ("m ∈ PMap(ExVar,Val)")
monos PMap_mono
type_intros A_into_univ mapQU

consts
ve_owr :: "[i,i,i] => i"
ve_dom :: "i=>i"
ve_app :: "[i,i] => i"


primrec "ve_owr(ve_mk(m), x, v) = ve_mk(map_owr(m,x,v))"

primrec "ve_dom(ve_mk(m)) = domain(m)"

primrec "ve_app(ve_mk(m), a) = map_app(m,a)"

definition
ve_emp :: i where
"ve_emp == ve_mk(map_emp)"


(* Elimination rules *)

lemma ValEnvE:
"[| ve ∈ ValEnv; !!m.[| ve=ve_mk(m); m ∈ PMap(ExVar,Val) |] ==> Q |] ==> Q"
apply (unfold Part_def Val_def ValEnv_def, clarify)
apply (erule Val_ValEnv.cases)
apply (auto simp add: Val_def Part_def Val_ValEnv.con_defs)
done

lemma ValE:
"[| v ∈ Val;
!!c. [| v = v_const(c); c ∈ Const |] ==> Q;
!!e ve x.
[| v = v_clos(x,e,ve); x ∈ ExVar; e ∈ Exp; ve ∈ ValEnv |] ==> Q
|] ==>
Q"

apply (unfold Part_def Val_def ValEnv_def, clarify)
apply (erule Val_ValEnv.cases)
apply (auto simp add: ValEnv_def Part_def Val_ValEnv.con_defs)
done

(* Nonempty sets *)

lemma v_closNE [simp]: "v_clos(x,e,ve) ≠ 0"
by (unfold QPair_def QInl_def QInr_def Val_ValEnv.con_defs, blast)

declare v_closNE [THEN notE, elim!]


lemma v_constNE [simp]: "c ∈ Const ==> v_const(c) ≠ 0"
apply (unfold QPair_def QInl_def QInr_def Val_ValEnv.con_defs)
apply (drule constNEE, auto)
done


(* Proving that the empty set is not a value *)

lemma ValNEE: "v ∈ Val ==> v ≠ 0"
by (erule ValE, auto)

(* Equalities for value environments *)

lemma ve_dom_owr [simp]:
"[| ve ∈ ValEnv; v ≠0 |] ==> ve_dom(ve_owr(ve,x,v)) = ve_dom(ve) ∪ {x}"
apply (erule ValEnvE)
apply (auto simp add: map_domain_owr)
done

lemma ve_app_owr [simp]:
"ve ∈ ValEnv
==> ve_app(ve_owr(ve,y,v),x) = (if x=y then v else ve_app(ve,x))"

by (erule ValEnvE, simp add: map_app_owr)

(* Introduction rules for operators on value environments *)

lemma ve_appI: "[| ve ∈ ValEnv; x ∈ ve_dom(ve) |] ==> ve_app(ve,x):Val"
by (erule ValEnvE, simp add: pmap_appI)

lemma ve_domI: "[| ve ∈ ValEnv; x ∈ ve_dom(ve) |] ==> x ∈ ExVar"
apply (erule ValEnvE, simp)
apply (blast dest: pmap_domainD)
done

lemma ve_empI: "ve_emp ∈ ValEnv"
apply (unfold ve_emp_def)
apply (rule Val_ValEnv.intros)
apply (rule pmap_empI)
done

lemma ve_owrI:
"[|ve ∈ ValEnv; x ∈ ExVar; v ∈ Val |] ==> ve_owr(ve,x,v):ValEnv"
apply (erule ValEnvE, simp)
apply (blast intro: pmap_owrI Val_ValEnv.intros)
done

end