[GHC] #14254: The Binary instance for TypeRep smells a bit expensive

[GHC]

#14254: The Binary instance for TypeRep smells a bit expensive
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        Reporter:  dfeuer            |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:  Typeable
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D3998
       Wiki Page:                    |
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Comment (by dfeuer):

 I have the feeling that `typeRepKind` is just too expensive, considering
 that it has to be called for `dynApply`, `funResultTy`, and
 deserialization. Just how bad would it be to expand the `TrApp` and
 `TrFun` constructors just enough to fit the result kind? Alternatively,
 would it make sense to add the kind representation to `Dynamic` and to the
 constraints on `funResultTy` and deserialization?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14254#comment:4>
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