src/HOL/Prolog/Func.thy

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/Prolog/Func.thy	Fri Jun 02 12:44:04 2000 +0200
@@ -0,0 +1,57 @@
+(* untyped functional language, with call by value semantics *)
+
+Func = HOHH +
+
+types tm
+
+arities tm :: term
+
+consts	abs	:: (tm => tm) => tm
+	app	:: tm => tm => tm
+
+	cond	:: tm => tm => tm => tm
+	fix	:: (tm => tm) => tm
+
+	true,
+	false	:: tm
+	"and"	:: tm => tm => tm	(infixr 999)
+	"eq"	:: tm => tm => tm	(infixr 999)
+
+	"0"	:: tm			("Z")
+	S	:: tm => tm
+(*
+	"++", "--",
+	"**"	:: tm => tm => tm	(infixr 999)
+*)
+	eval	:: [tm, tm] => bool
+
+arities tm :: plus
+arities tm :: minus
+arities tm :: times
+
+rules	eval "
+
+eval (abs RR) (abs RR)..
+eval (app F X) V :- eval F (abs R) & eval X U & eval (R U) V..
+
+eval (cond P L1 R1) D1 :- eval P true  & eval L1 D1..
+eval (cond P L2 R2) D2 :- eval P false & eval R2 D2..
+eval (fix G) W   :- eval (G (fix G)) W..
+
+eval true  true ..
+eval false false..
+eval (P and Q) true  :- eval P true  & eval Q true ..
+eval (P and Q) false :- eval P false | eval Q false..
+eval (A1 eq B1) true  :- eval A1 C1 & eval B1 C1.. 
+eval (A2 eq B2) false :- True..
+
+eval Z Z..
+eval (S N) (S M) :- eval N M..
+eval ( Z    + M) K     :- eval      M  K..
+eval ((S N) + M) (S K) :- eval (N + M) K..
+eval (N     - Z) K     :- eval  N      K..
+eval ((S N) - (S M)) K :- eval (N- M)  K..
+eval ( Z    * M) Z..
+eval ((S N) * M) K :- eval (N * M) L & eval (L + M) K"
+
+end