Functor
From HaskellWiki
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+ | {{Standard class|Functor|module=Control.Monad}} | ||
The '''Functor''' class is defined like this: | The '''Functor''' class is defined like this: | ||
Revision as of 03:09, 2 January 2006
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)