[GHC] #4347: Asymmetry of (impredicative) instantiation/higher rank types

[GHC]

#4347: Asymmetry of (impredicative) instantiation/higher rank types
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    Reporter:  dolio                    |        Owner:                           
        Type:  bug                      |       Status:  new                      
    Priority:  normal                   |    Milestone:  7.4.1                    
   Component:  Compiler (Type checker)  |      Version:  7.1                      
    Keywords:                           |     Testcase:                           
   Blockedby:                           |   Difficulty:                           
          Os:  Linux                    |     Blocking:                           
Architecture:  x86_64 (amd64)           |      Failure:  GHC rejects valid program
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Comment(by carlhowells):

 I've recently run into this.  It's not fun when my code that worked on GHC
 6.12 doesn't work on GHC 7.  Any chance this'll get done before 7.4?

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4347#comment:3>
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