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

Wed, 13 Jan 2010 08:47:42 -0600 Antoine Latter:

On Wed, Jan 13, 2010 at 8:44 AM, Eugen Zagorodniy 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.

Sure that is it. I should pay more attention to standard type classes. Thanks!