[GHC] #8565: New GeneralisedNewtypeDeriving needs help with higher rank types

[GHC]

#8565: New GeneralisedNewtypeDeriving needs help with higher rank types
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        Reporter:  simonpj                       |            Owner:
            Type:  bug                           |           Status:  new
        Priority:  normal                        |        Milestone:
       Component:  Compiler                      |          Version:  7.6.3
      Resolution:                                |         Keywords:
Operating System:  Unknown/Multiple              |     Architecture:
 Type of failure:  None/Unknown                  |  Unknown/Multiple
       Test Case:                                |       Difficulty:
  typecheck/should_compile/T8565                 |  Unknown
        Blocking:                                |       Blocked By:
                                                 |  Related Tickets:
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Comment (by nomeata):

 I’m working on
 {{{
 instance (forall a. (Coercible t1 t2)) => Coercible (forall a. t1) (forall
 a. t2)
 }}}
 and am almost done, just trying to get the desugarer cope with new type
 variables in derived constraints.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8565#comment:6>
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