Functor
From HaskellWiki
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− | {{Standard class|Functor|module=Control.Monad|module=doc=Control-Monad|package=base}} |
+ | {{Standard class|Functor|module=Control.Monad|module-doc=Control-Monad|package=base}} |
The '''Functor''' class is defined like this: |
The '''Functor''' class is defined like this: |
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Revision as of 03:20, 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)