[GHC] #12369: data families shouldn't be required to have return kind *, data instances should

[GHC]

#12369: data families shouldn't be required to have return kind *, data instances
should
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        Reporter:  ekmett            |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:  8.2.1
       Component:  Compiler (Type    |              Version:  8.0.1
  checker)                           |
      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):

 Replying to [comment:6 goldfire]:
 > So I think this kind of construct is best off waiting until we solve the
 simpler case of normal unlifted datatypes before we try unlifted data
 families.

 Awesome! Maybe you can combine them into fixed point that is rep-poly ;)

 > You just want to say `data instance Array Int#`, which indeed works
 fine.

 Haha oops.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12369#comment:7>
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