More properties of double double_compare_to_input x | x > 0 = double x > x | x < 0 = double x < x | x == 0 = True double_minus_input x = double x - x == x
-- splitting an empty list results in an empty list split char [] = [] split char str | null after = before : [] | otherwise = before : split char (tail after) where before = takeWhile (/=char) str after = dropWhile (/=char) str