[GHC] #4370: Bring back monad comprehensions

[GHC]

#4370: Bring back monad comprehensions
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    Reporter:  simonpj           |        Owner:  nsch        
        Type:  feature request   |       Status:  new         
    Priority:  normal            |    Milestone:  7.2.1       
   Component:  Compiler          |      Version:  6.12.3      
    Keywords:                    |     Testcase:              
   Blockedby:                    |   Difficulty:              
          Os:  Unknown/Multiple  |     Blocking:              
Architecture:  Unknown/Multiple  |      Failure:  None/Unknown
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Comment(by nsch):

 I just did a rebuild with the darcs repo and everything did work as
 expected (we were using git before). I'll upload the darcs patch for the
 compiler aswell.

 So to test this you should:

  * Apply the `group_zip.patch` patch to the base library and
  * apply the `monad-comprehension-alpha.patch` patch to the main ghc repo.

 There should be no conflicts/errors.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4370#comment:43>
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