[GHC] #9223: Type equality makes type variable untouchable

[GHC]

#9223: Type equality makes type variable untouchable
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              Reporter:  Feuerbach   |            Owner:
                  Type:  bug         |           Status:  new
              Priority:  normal      |        Milestone:
             Component:  Compiler    |          Version:  7.8.2
  (Type checker)                     |         Keywords:
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Unknown
  Unknown/Multiple                   |       Blocked By:
       Type of failure:              |  Related Tickets:
  None/Unknown                       |
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Comment (by simonpj):

 @porges: Yes, the two types should be equivalent.  GHC HEAD (and 7.10)
 should be better in this regard.  Can you try your example with that?

 @goldire: you may be right.  But even if you are, there's a balance
 between trying to make type inference as clever as possible and making it
 so unpredictable that no one knows whether it'll work or not.  But I'm
 open to suggetions.

 Simon

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9223#comment:12>
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