[GHC] #9123: Need for higher kinded roles

[GHC]

#9123: Need for higher kinded roles
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        Reporter:  simonpj           |                Owner:  goldfire
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  7.8.2
  checker)                           |             Keywords:  Roles,
      Resolution:                    |  QuantifiedConstraints
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by goldfire):

 I had seen the bit you had hidden under the carpet, but was still stuck on
 the "completely false" part -- glad we agree there. :)

 And I'm glad that the current implementation is correct.

 If you're documenting this, you may wish to refresh yourself on Section
 5.3.1 of the
 [https://repository.brynmawr.edu/cgi/viewcontent.cgi?referer=&httpsredir=1&article=1010&context=compsci_pubs
 JFP "Safe Coercions" paper], which goes over all this in some detail.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9123#comment:54>
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