[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:27 crockeea]:
 > To echo @dreixel: What exactly *is* SPJ's suggestion? Is it to not
 *automatically* derive `Typeable` instances for poly-kinded type
 constructors, or is to disallow standalone-derived instances as well?

 Presumably it would be safe to allow a *single* standalone derivation in
 the same module that defines the type, as long as it's of actual
 monomorphic kind.  That way, at least `Proxy` could still have a `* -> *`
 instance, which might be the one that is used the most in practice?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9858#comment:28>
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