[Haskell-cafe] Re: Composing monads

[Jules Bean]

> module Main (Main.main) where
> import Control.Monad
> import System.IO
> 
> (>*>) :: Monad m => m () -> (a -> m ()) -> (a -> m ())
> (>*>) f f' = \a -> do{
>   f;
>   f' a;
> }
> 
> main :: IO ()
> main = mapM_ ((putStrLn "") >*> putStrLn) $
>           map show [1,2,3]

There is nothing wrong with that, but I would normally write:

mapM_ (\a -> putStrLn "" >> putStrLn a) $ map show [1,2,3]

...i.e. I wouldn't be afraid of a lambda in a case like that. IME it's 
moderately common to have to do:

mapM_ (\a -> some stuff >> something_with a >> some stuff) ll

Jules