[GHC] #9117: Coercible constraint solver misses one

[GHC]

#9117: Coercible constraint solver misses one
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        Reporter:  goldfire          |            Owner:  nomeata
            Type:  bug               |           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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Comment (by nomeata):

 Yes, that’s a better example. So we have a dilemma: Should we support
 recursive newtypes better, or should we support different
 internal/external coercions better?

 Your trick in comment:13, shouldn’t that work for newtypes just as well?
 So maybe the original order was better after all...

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9117#comment:22>
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