Functor
From HaskellWiki
Revision as of 18:52, 19 September 2012 by Henk-Jan van Tuyl (Talk | contribs)
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)