Functor
From HaskellWiki
Revision as of 21:10, 1 November 2009 by Lemming (talk | contribs) (Main article in category Functor)
import Control.Monad |
The Functor class is defined like this:
class Functor f where fmap :: (a -> b) -> f a -> f b
All instances of Functor should obey:
fmap id = id fmap (p . q) = (fmap p) . (fmap q)