[GHC] #9747: Odd failure to deduce a constraint

[GHC]

#9747: Odd failure to deduce a constraint
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              Reporter:  acowley     |            Owner:
                  Type:  bug         |           Status:  infoneeded
              Priority:  normal      |        Milestone:
             Component:  Compiler    |          Version:  7.8.3
            Resolution:              |         Keywords:  TypeFamilies
      Operating System:              |  ConstraintKinds
  Unknown/Multiple                   |     Architecture:  Unknown/Multiple
       Type of failure:              |       Difficulty:  Unknown
  None/Unknown                       |       Blocked By:
             Test Case:              |  Related Tickets:
              Blocking:              |
Differential Revisions:              |
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Comment (by acowley):

 Sorry I wasn't clear, you need to uncomment the definition of `baz` to see
 the error.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9747#comment:2>
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