[Haskell-beginners] lazy mapM

Hi again, Given the following code: g :: IO String -> IO String f :: [IO String] -> IO [ String ] f = mapM g The implementation of f is wrong because I would like to: 1. Make f behave lazy Its input list is made of lines read from stdin and I want it to process lines one by one as they are entered by the user. 2. Implement f such that it stops consuming items from the input list when the input item meets some condition. For example: isExit item = ("exit" == item) I tried to implement my own custom iteration by recursion but I got stuck in the combination of IO and list monads. Any help is appreciated. Thanks!