[GHC] #15322: `KnownNat` does not imply `Typeable` any more when used with plugin

[GHC]

#15322: `KnownNat` does not imply `Typeable` any more when used with plugin
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        Reporter:  chshersh          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.4.3
      Resolution:                    |             Keywords:
                                     |  typeable,knownnat
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #10348            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 > I have used type-nats a few times and every time I used them, I have
 been bitten by GHC not recognizing apartness between nats

 Interesting. Another possibility would be to build into GHC more knowledge
 about `KnownNat`.

 But making it possible for plugins to specify apartness would also be
 good.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15322#comment:16>
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