[GHC] #9123: Need for higher kinded roles

[GHC]

#9123: Need for higher kinded roles
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        Reporter:  simonpj           |            Owner:
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.8.2
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by ekmett):

 Richard,

 The asymmetry is annoying but without it you cannot write the lifting for
 `Representational (StateT s m)`.

 I started without it for the same reason you dislike it and added it only
 when forced.

 Simon,

 As for dropping join for now I'd be sad to see it lost, but if we at least
 commit to seeking a solution to this problem, I'd be personally okay with
 sacrificing it for now.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9123#comment:11>
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