--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Nominal/ExPS3.thy	Tue Mar 23 09:05:23 2010 +0100
@@ -0,0 +1,37 @@
+theory ExPS3
+imports "Parser"
+begin
+
+(* example 3 from Peter Sewell's bestiary *)
+
+atom_decl name
+
+ML {* val _ = recursive := false  *}
+nominal_datatype exp =
+  VarP "name"
+| AppP "exp" "exp"
+| LamP x::"name" e::"exp" bind x in e
+| LetP x::"name" p::"pat3" e1::"exp" e2::"exp" bind x in e2, bind "bp'' p" in e1
+and pat3 =
+  PVar "name"
+| PUnit
+| PPair "pat3" "pat3"
+binder
+  bp'' :: "pat3 \<Rightarrow> atom set"
+where
+  "bp'' (PVar x) = {atom x}"
+| "bp'' (PUnit) = {}"
+| "bp'' (PPair p1 p2) = bp'' p1 \<union> bp'' p2"
+
+thm exp_pat3.fv
+thm exp_pat3.eq_iff
+thm exp_pat3.bn
+thm exp_pat3.perm
+thm exp_pat3.induct
+thm exp_pat3.distinct
+thm exp_pat3.fv[simplified exp_pat3.supp]
+
+end
+
+
+