[GHC] #12708: RFC: Representation polymorphic Num

[GHC]

#12708: RFC: Representation polymorphic Num
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        Reporter:  Iceland_jack      |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Core Libraries    |              Version:  8.0.1
      Resolution:                    |             Keywords:
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 Iceland_jack):

 With it and `RebindableSyntax` you can write

 {{{#!hs
 foo :: Int
 foo = I# u + 10 * 4 where
   u :: Int#
   u = 10 + 10 * 4

 bar :: String
 bar = show @PtrRepLifted @Int  24
    ++ show @IntRep       @Int# 24
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12708#comment:2>
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