[Periodic]

It needs to be fixed up a bit. You can somewhat resolve this issue by compiling with -Wall, at which point it will warn you that your pattern matching is non-exhaustive.

    import System.IO

    divide :: Int -> Int -> Maybe Int
    divide x 0 = Nothing
    divide x y = Just $ x `div` y

    printResult :: Maybe Int -> IO ()
    printResult (Just x) = print x

    main = do
        putStr "Type a number: "
        hFlush stdout
        x <- readLn
        printResult $ divide 42 x