Re: [GHC] #8865: Cannot derive well-kinded instance of form ‘Category

GHC ghc-devs at haskell.org
Mon Mar 10 14:12:17 UTC 2014


#8865: Cannot derive well-kinded instance of form ‘Category
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        Reporter:  adinapoli                  |            Owner:
            Type:  bug                        |           Status:  closed
        Priority:  normal                     |        Milestone:  7.8.1
       Component:  Compiler                   |          Version:
      Resolution:  fixed                      |  7.8.1-rc2
Operating System:  MacOS X                    |         Keywords:
 Type of failure:  GHC rejects valid program  |     Architecture:  x86_64
       Test Case:                             |  (amd64)
        Blocking:                             |       Difficulty:  Unknown
                                              |       Blocked By:
                                              |  Related Tickets:
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Comment (by thoughtpolice):

 Oh, and really, Category isn't necessarily the only thing affected - per
 the test case, I would actually expect *anything* with a polymorphic kind
 inferred by `PolyKinds` being enabled will no longer be GND-able, which is
 quite a shame it would seem.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8865#comment:8>
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