freemo

mergeSort :: (Ord a) => [a] -> [a]
mergeSort x
    | len <= 1 = x
    | otherwise = combine (mergeSort upper) (mergeSort lower)
    where len = length x
          middle = quot len 2
          upper = take middle x
          lower = drop middle x
          combine x [] = x
          combine [] x = x

freemo

prime :: Int -> Bool
prime x
    | x == 1 = False
    | x == 2 = True
    | x == 3 = True
    | x `mod` 2 == 0 = False
    | x `mod` 3 == 0 = False
    | otherwise = all (\y -> x `mod` y /= 0) $ dividends x
    where
        dividends z =