diff --git a/demo/quicksort b/demo/quicksort
index b0339d3..3917ce2 100755
Binary files a/demo/quicksort and b/demo/quicksort differ
diff --git a/demo/quicksort.crf b/demo/quicksort.crf
index 61ab3a4..5728051 100644
--- a/demo/quicksort.crf
+++ b/demo/quicksort.crf
@@ -1,10 +1,6 @@
-
-filter : (a -> Bool) -> List a -> List a
-filter p xs = case xs of
-    Nil => Nil
-    Cons x xs => case p x of
-        True => Cons x (filter p xs)
-        False => filter p xs
+data List a where
+    Nil : List a
+    Cons : a -> List a -> List a
 
 quicksort : List Int -> List Int
 quicksort xs = case xs of
@@ -13,10 +9,20 @@ quicksort xs = case xs of
                  let bigger = quicksort (filter (\y. a < y) xs) in
                  smaller ++ (Cons a bigger)
 
+.++ list1 list2 = case list1 of
+    Nil => list2
+    Cons x xs => Cons x (xs ++ list2)
+
+filter : (a -> Bool) -> List a -> List a
+filter p xs = case xs of
+    Nil => Nil
+    Cons x xs => case p x of
+        True => Cons x (filter p xs)
+        False => filter p xs
+
 mkDescList : Int -> Int -> List Int
 mkDescList from to = case from == to of
     True => Nil
     False => Cons from (mkDescList (from - 1) to)    
     
 main = printList (quicksort (mkDescList 1000 0))
-