[GHC] #4159: move Monad and MonadFix instances for Either from mtl to base

[GHC]

#4159: move Monad and MonadFix instances for Either from mtl to base
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    Reporter:  ross              |       Owner:                
        Type:  proposal          |      Status:  new           
    Priority:  normal            |   Component:  libraries/base
     Version:  6.12.3            |    Keywords:                
          Os:  Unknown/Multiple  |    Testcase:                
Architecture:  Unknown/Multiple  |     Failure:  None/Unknown  
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 These patches move the Monad and MonadFix instances for Either (currently
 in the mtl package) to Control.Monad.Instances and Control.Monad.Fix
 respectively (both in the base package).  The Monad instance is still an
 orphan, to retain Haskell 98 compatibility, but the MonadFix instance is
 together with its class.  The Error constraint is removed from both
 instances, and the default definition of fail is used.

 Discussion deadline: 20th July 2010

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4159>
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