[GHC] #9112: data families with representational matching

[GHC]

#9112: data families with representational matching
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        Reporter:  jwlato            |            Owner:
            Type:  feature request   |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.8.2
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Changes (by liyang):

 * cc: hackage.haskell.org@… (added)


Comment:

 I'm not sure using [http://hackage.haskell.org/package/vector-th-unbox
 vector-th-unbox] counts as a complete workaround, as it amounts to giving
 the instance in full.

 Without coerce, I think it's also susceptible to the expensive "map id"
 issue.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9112#comment:1>
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