Fix quicksort example

sample-programs/working/quicksort.crf

@@ -0,0 +1,44 @@
+toStr : List Int -> List Char
+toStr xs = case xs of
+    Cons a as => Cons (toChar a) (toStr as)
+    Nil => Nil
+
+toChar : Int -> Char
+toChar x = case x of
+    0 => '0'
+    1 => '1'
+    2 => '2'
+    3 => '3'
+    4 => '4'
+    5 => '5'
+    6 => '6'
+    7 => '7'
+    8 => '8'
+    9 => '9'
+
+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
+
+.++ : List a -> List a -> List a
+.++ as bs = case as of
+    Nil => bs
+    Cons x xs => Cons x (xs ++ bs)
+
+quicksort : List Int -> List Int
+quicksort xs = case xs of
+    Nil => Nil
+    Cons a as => let smaller = quicksort (filter (\y. y < a) xs)
+                  in let bigger = quicksort (filter (\y. a < y) xs)
+                      in smaller ++ (Cons a bigger)
+
+descList : Int -> Int -> List Int
+descList from to = case to < from of
+   False => Cons to (descList from (to - 1)) 
+   True => Nil
+
+main = let list = Cons 5 (Cons 2 (Cons 8 (Cons 9 (Cons 6 (Cons 0 (Cons 1 Nil)))))) in 
+       printStr (toStr (quicksort list))