[GHC] #10524: PolyKinds doesn't interact well with DeriveFunctor

[GHC]

#10524: PolyKinds doesn't interact well with DeriveFunctor
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        Reporter:  RyanGlScott       |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.10.1
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:  #10561            |  Differential Revisions:
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"ceb3c8448dfba23aa98a710f846304158c1c584b/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="ceb3c8448dfba23aa98a710f846304158c1c584b"
 Improve error message for Typeable k (T k)

 GHC can't yest build a TypeRep for a type involving kind variables.
 (We await kinds = types for that.)  But the error message was terrible,
 as fixing #10524 reminded me.

 This improves it a lot.
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10524#comment:9>
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