[GHC] #9858: Typeable instances should be kind-aware

[GHC]

#9858: Typeable instances should be kind-aware
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        Reporter:  dreixel           |                   Owner:
            Type:  bug               |                  Status:  merge
        Priority:  highest           |               Milestone:  7.10.2
       Component:  Compiler          |                 Version:  7.9
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |  typecheck/should_fail/T9858a,
                                     |  should_run/T9858b
                                     |                Blocking:
                                     |  Differential Revisions:  Phab:D652
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"c0b5adbd1a04dd1c7916c1240e50a936e826136d/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="c0b5adbd1a04dd1c7916c1240e50a936e826136d"
 Do not decompose => (Trac #9858)

 We really don't want to unify (a b) with (Eq a => ty).
 The ever-ingenious Oerjan discovered this problem;
 see comment:101 in Trac #9858.

 See Note [Decomposing fat arrow c=>t] in Type.hs
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9858#comment:105>
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