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Functor

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(Added section "More reading" with a link to "The functor design pattern")
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{{Standard class|Functor|module=Control.Monad}}
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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:
  
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  fmap id = id
 
  fmap id = id
 
  fmap (p . q) = (fmap p) . (fmap q)
 
  fmap (p . q) = (fmap p) . (fmap q)
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== More reading ==
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* [http://www.haskellforall.com/2012/09/the-functor-design-pattern.html The functor design pattern]
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[[Category:Functor|*]]

Revision as of 18:52, 19 September 2012

Functor class (base)
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)


More reading