[GHC] #12837: KnownNat and KnownSymbol should be abstract

[GHC]

#12837: KnownNat and KnownSymbol should be abstract
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        Reporter:  adamgundry        |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:  newcomer
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC accepts       |  Unknown/Multiple
  invalid program                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by pbg):

 I'm a total newbie so can't comment on whether this is a desired change.
 However in case it is - would extending the code that was added for
 `Typeable` (#8132) to account for additional class names be the way to go
 here?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12837#comment:1>
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