Well, here is your problem: map :: (a -> b) -> [a] -> [b] putStrLn :: String -> IO () qlist :: [String] map putStrLn :: [String] -> [IO ()] map putStrLn qlist :: [IO ()] The type of (map putStrLn qlist) is not of the form IO a, so it's not an action which can be run. There are some useful prelude functions called sequence and sequence_ whose types are as follows: sequence :: (Monad m) => [m a] -> m [a] sequence_ :: (Monad m) => [m a] -> m () they will put that list of actions into a single action which can then be run. This pattern of mapping over a list and sequencing is so common that it has a name: mapM :: Monad m => (a -> m b) -> [a] -> m [b] mapM_ :: Monad m => (a -> m b) -> [a] -> m () -- similar, but throws away computed results. which is exactly what you're looking for. :) - Cale On 19/08/05, Brian McQueen wrote:

I have a simple list like this:

qlist = ["ll", "kkkkkkk", "ddddd"]

Why is it OK to do this:

qwrap [] = putStrLn ":" qwrap (a:as) = do putStrLn a qwrap as

qwap qlist

but not this:

map putStrLn qlist

What is going on in the map function?

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