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

[GHC]

#9858: Typeable instances should be kind-aware
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        Reporter:  dreixel           |                   Owner:  dreixel
            Type:  bug               |                  Status:  new
        Priority:  highest           |               Milestone:  7.10.1
       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:                    |                Blocking:
                                     |  Differential Revisions:
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Comment (by oerjan):

 Replying to [comment:58 goldfire]:
 > This defaulting to `*` is precisely what happens without `PolyKinds` on.
 So anyone not worried about kind variables won't need to.

 Oh, so it is, on second testing.  My first test (with my mock
 implementation, whose inferred types I think are "close enough" for the
 purpose) failed, but I only removed `PolyKinds` and must have left some
 other extension that implied it.

 > But I don't like this defaulting behavior if `PolyKinds` ''is'' on. If a
 user has specified `PolyKinds` and writes the code in comment:57, I would
 want an error to be reported. The choice of the kind variable here is
 potentially relevant to the programmer's desired behavior, and I think
 silently guessing a value is wrong here.

 Good point, although I'm still wondering which option will break the least
 code...

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9858#comment:59>
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