[GHC] #14190: Typeable imposes seemingly redundant constraints on polykinded instances

[GHC]

#14190: Typeable imposes seemingly redundant constraints on polykinded instances
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        Reporter:  dfeuer            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler (Type    |              Version:  8.2.1
  checker)                           |
      Resolution:                    |             Keywords:  Typeable
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by dfeuer):

 I think the ideal ergonomics with the best performance would likely be to
 leave the class as it is, extract the typerep-of-kind info as needed in
 the `DFun`s, and hack the constraint solver to let it solve `Typeable k`
 from `Typeable (a :: k)`.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14190#comment:7>
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