
diff -r 893f0314a88b -r fff2b8d356a5 thys/CountSnoc.thy
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/thys/CountSnoc.thy	Tue Oct 07 12:33:27 2014 +0100
@@ -0,0 +1,27 @@
+theory CountSnoc
+imports Main
+begin
+
+
+datatype 'a myList = Nil | Cons 'a "'a myList"
+
+fun app_list :: "'a myList \<Rightarrow> 'a myList \<Rightarrow> 'a myList" where
+"app_list Nil ys = ys" |
+"app_list (Cons x xs) ys = Cons x (app_list xs ys)"
+
+fun rev_list :: "'a myList \<Rightarrow> 'a myList" where
+"rev_list Nil = Nil" |
+"rev_list (Cons x xs) = app_list (rev_list xs) (Cons x Nil)"
+
+fun count_list :: "'a \<Rightarrow> 'a list \<Rightarrow> nat" where
+"count_list x [] = 0" |
+"count_list x (y#xs) = (
+  if x = y then Suc(count_list x xs) 
+  else count_list x xs)"
+
+value "count_list 2 [1,2,1,1]"
+ 
+
+
+
+




