[GHC] #4935: New type error in GHC 7.1 with TypeFamilies, Rank2Types

[GHC]

#4935: New type error in GHC 7.1 with TypeFamilies, Rank2Types
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    Reporter:  patrick_premont          |        Owner:              
        Type:  bug                      |       Status:  new         
    Priority:  normal                   |    Milestone:              
   Component:  Compiler (Type checker)  |      Version:  7.1         
    Keywords:                           |     Testcase:              
   Blockedby:                           |   Difficulty:              
          Os:  Windows                  |     Blocking:              
Architecture:  x86                      |      Failure:  None/Unknown
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Comment(by simonpj):

 Yes this is a definite bug; thank you!  Should not be hard to fix.

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4935#comment:1>
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