[Haskell-cafe] how to apply a function which returns IO() to a list?

Stefan Holdermans stefan at cs.uu.nl
Wed Jun 14 05:50:35 EDT 2006


> I have this function which write a file:
> writeHtml b x y = do
>                         writeFile (b ++ ".html")  (htmlCode b x y)
> i need to apply to each member of a given list:

Have a look at the mapM and mapM_ functions from the Prelude.  
Instantiated to IO, these have the following types:

   mapM  :: (a -> IO b) -> [a] -> IO [b]
   mapM_ :: (a -> IO b) -> [a] -> m ()



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