new tasks

Task/Ackermann_function/Haskell/ackermann_function-2.hs

@@ -0,0 +1,9 @@
+-- everything here are [Int] or [[Int]], which would overflow
+-- * had it not overrun the stack first *
+ackermann = iterate ack [1..] where
+	ack a = s where
+		s = a!!1 : f (tail a) (zipWith (-) s (1:s))
+	f a (b:bs) = (head aa) : f aa bs where
+		aa = drop b a
+
+main = mapM_ print $ map (\n -> take (6 - n) $ ackermann !! n) [0..5]