mappy.hs

-- | Conditionally apply the monadic f to the Maybe value when it is
--   Just and wrap the /inner/ value in Just, or return Nothing
(=<?) :: (Monad m) => (a -> m b) -> Maybe a -> m (Maybe b)
f =<? (Just a) = return . Just =<< f a
f =<?  Nothing = return Nothing

-- can this not be done with some variation of liftM and fmap?

Have a peek on Monad transformers. I think that's just what you're doing.

Ah yes. Thanks for that link.