[Haskell-beginners] Trivial function of type (a -> b) -> Maybe a -> Maybe b

[Antoine Latter]

On Wed, Jan 13, 2010 at 8:44 AM, Eugen Zagorodniy
<e.zagorodniy at gmail.com> wrote:
> Greetings!
>
> I looked at documentation of Maybe type and suprisingly found no
> function like
>
> maybize             :: (a -> b) -> Maybe a -> Maybe b
> maybize f Nothing   =  Nothing
> maybize f (Just x)  =  Just (f x)
>

Have you looked at:

fmap :: Functor f => (a -> b) -> f a -> f b

It will do what you want, and has the bonus of doing the same
operation for a lot more structures.

Antoine

http://haskell.org/ghc/docs/latest/html/libraries/base-4.2.0.0/Prelude.html#v:fmap