import Control.Applicative

data MyCoolIO a = MCIO (IO a)

instance Functor MyCoolIO where
  fmap f (MCIO xIO)  =  MCIO $ fmap f xIO

instance Applicative MyCoolIO where
  pure = MCIO . pure
  (MCIO fIO) <*> (MCIO xIO)  =  MCIO $ fIO <*> xIO

instance Monad MyCoolIO where
  return = pure
  
  (MCIO xIO) >>= f          =  MCIO $ xIO >>= \x -> (let (MCIO r) = f x in r)
  (MCIO xIO) >> (MCIO yIO)  =  MCIO $ yIO >>= \y -> (xIO >> return y)

myPutStrLn :: String -> MyCoolIO ()
myPutStrLn s = MCIO $ putStrLn s

myMain :: MyCoolIO () -> IO ()
myMain (MCIO io) = io

main = myMain $ do
  myPutStrLn "first"
  myPutStrLn "second"
  myPutStrLn "third"