quicksort quickcheck

quickcheck-by-example/quicksort.hs

@@ -0,0 +1,21 @@
+import Test.QuickCheck
+import Data.List
+
+quicksort :: Ord a => [a] -> [a]
+quicksort [] = []
+quicksort (x:xs) = quicksort small ++ [x] ++ quicksort large
+ where
+ small = filter (<x) xs
+ large = filter (>=x) xs
+
+isSorted :: Ord a => [a] -> Bool
+isSorted [] = True
+isSorted [x] = True
+isSorted (x:y:xs) = x <= y && isSorted xs
+
+idempotent_property xs = quicksort (quicksort xs) == quicksort xs
+sorted_pproperty xs = isSorted (quicksort xs)
+
+main = do
+ quickCheck (idempotent_property :: [Integer] -> Bool)
+ quickCheck (sorted_pproperty :: [Integer] -> Bool)