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

GHC ghc-devs at haskell.org
Mon Mar 10 11:11:34 UTC 2014


#8865: Cannot derive well-kinded instance of form ‘Category
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        Reporter:  adinapoli                  |            Owner:
            Type:  bug                        |           Status:  new
        Priority:  normal                     |        Milestone:  7.8.1
       Component:  Compiler                   |          Version:
      Resolution:                             |  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 Simon Peyton Jones <simonpj@…>):

 In [changeset:"f521a26cb741409011137115d17232df901c3c94/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="f521a26cb741409011137115d17232df901c3c94"
 Unify, rather than match, in GND processing (fixes Trac #8865)

 Yet another small way in which polymorphic kinds needs a bit of care
 See Note [Unify kinds in deriving] in TcDeriv
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8865#comment:4>
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