Re: [Haskell-cafe] A function for Maybes

fmap. e.g.: Prelude> fmap ('c':) (Just "a") Just "ca" Prelude> fmap ('c':) Nothing Nothing Prelude> /g 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

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