[GHC] #12381: Type family not reduced

[GHC]

#12381: Type family not reduced
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        Reporter:  bgamari           |                Owner:
            Type:  bug               |               Status:  merge
        Priority:  normal            |            Milestone:  8.0.2
       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 simonpj):

 Let's add this as a regression test though. (Redundant perhaps, but
 still.)

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12381#comment:3>
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