[Haskell-beginners] point-free + IO Monad

I have the following code: f1 :: String -> String f2 :: IO String -> IO () f2 a = do b <- a putStr $ f1 b How can I write the function f2 in a point-free style? I have tried this: f2 = return.f1 >>= putStr ...but it doesn't work. Thanks!