Even more succinctly:
sequence_ . map is mapM_, and putStrLn . show is print, so you get:
mapM_ print films
Dan
On Sun, May 10, 2009 at 9:59 PM, Alex MDC
2009/5/11 applebiz89
I know to use show and putStrLn but I just don't know how to put them into the function correctly
Well I hope we're not doing your homework for you but...
As putStrLn is in the IO monad, listFilms should at least have a signature like this:
listFilms :: [Film] -> IO ()
Now you know you want to call putStrLn on each item in the list. That means you want to join a bunch of functions return IO (). That sounds like a job for sequence_:
listFilms films = sequence_ $ map (putStrLn.show) films
Or the same thing more verbosely:
listFilms [] = return () listFilms (film:films) = do putStrLn (show film) listFilms films
Hope that helps, Alex
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