[GHC] #3335: make some Applicative functions into methods, and split off Data.Functor

[GHC]

#3335: make some Applicative functions into methods, and split off Data.Functor
-----------------------------+----------------------------------------------
Reporter:  ross              |          Owner:                  
    Type:  proposal          |         Status:  new             
Priority:  normal            |      Component:  libraries/base  
 Version:                    |       Severity:  normal          
Keywords:                    |       Testcase:                  
      Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
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 The following functions
 {{{
 (<$) :: Functor f => a -> f b -> f a
 (*>) :: Applicative f => f a -> f b -> f b
 (<*) :: Applicative f => f a -> f b -> f a
 some :: Alternative f => f a -> f [a]
 many :: Alternative f => f a -> f [a]
 }}}
 are moved into the corresponding classes, with the existing
 implementations as default definitions.  This gives people creating
 instances the option of defining specialized implementations of these
 functions, though they should be equivalent to the default definitions.

 Although (<$) is now a method of the Functor class, it is hidden in the
 re-export by the Prelude, Control.Monad and Monad.  The new module
 Data.Functor exposes the full class, plus the function (<$>).  These are
 also re-exported by Control.Applicative.

 Discussion on libraries at haskell.org to 20th July 2009.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3335>
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