Re: [Haskell-cafe] IO () and IO [()]

At Mon, 10 Mar 2008 22:11:33 +0000, Paulo J. Matos wrote:

I would like to know if in fact there's any difference in practice between (), [()], i.e. if in practice the difference matters.

Well, you could do something like this: outputLines :: Int -> IO [()] outputLines i = mapM (putStrLn . show) (take (i*2) $ iterate ((+) 1) 1) main = do l <- outputLines 10 putStrLn $ "I putted " ++ show (length l) ++ " lines." which is not very exciting in this case. But I think I may have done something similar in real code. j.