[GHC] #8631: Need ImpredicativeTypes for GeneralizedNewtypeDeriving?

[GHC]

#8631: Need ImpredicativeTypes for GeneralizedNewtypeDeriving?
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        Reporter:  goldfire          |            Owner:
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.7
      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 simonpj):

 `-XImpredicativeTypes` it not a very well-defined flag.  It might make
 this program compile, and I think it'd be safe to enable it for GND-
 produced code.  But it has had no love for many years.

 Do give it a try; which would make Q2 moot.

 Simon

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8631#comment:6>
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