Re: [Haskell-cafe] A function for Maybes

liftM (+2) (Just 3 Just 5

:t liftM forall r (m :: * -> *) a1. (Monad m) => (a1 -> r) -> m a1 -> m r liftM (+2) Nothing Nothing (Thanks to allbery_b for contributing to the discussion on #haskell) On 1/25/07, John Ky wrote:

Is there a built-in function that already does this?

foo :: (a -> b) -> Maybe a -> Maybe b foo f m | isNothing m = Nothing | otherwise = Just (f (fromJust m))

*Main> foo (+2) (Just 3) Just 5 *Main> foo (+2) Nothing Nothing

If so what is it?

If not, what should I call it?

Thanks

-John

_______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe