[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:  patch
        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):  Phab:D4000
       Wiki Page:                    |
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Comment (by dfeuer):

 Getting rid of `TrFun` does seem to simplify the story substantially. If
 we end up keeping it, by the way, I think we should really have a `Note`
 explaining why the fingerprinting is safe. It's because whenever `p q` is
 well-kinded, `p -> q` is not. Not a complicated matter, but I think one
 worth mentioning.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14190#comment:15>
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