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Functor

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{{Standard class|Functor|module=Control.Monad|package=base}}
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{{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:
   

Revision as of 03:20, 2 January 2006

Functor class (base)
import doc=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)