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

[GHC]

#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 simonpj):

 Oh, don't worry, I can reproduce it with
 {{{
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}

 module T8865 where
 import Control.Category

 newtype T a b = MkT (Either a b) deriving( Category )
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8865#comment:2>
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