[GHC] #9123: Need for higher kinded roles

[GHC]

#9123: Need for higher kinded roles
-------------------------------------+-------------------------------------
        Reporter:  simonpj           |                Owner:  goldfire
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler (Type    |              Version:  7.8.2
  checker)                           |             Keywords:  Roles,
      Resolution:  fixed             |  QuantifiedConstraints
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:  quantified-
                                     |  constraints/T9123{,a}
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by RyanGlScott):

 * testcase:   => quantified-constraints/T9123{,a}
 * status:  new => closed
 * resolution:   => fixed
 * milestone:   => 8.6.1


Comment:

 `QuantifiedConstraints`, which has become GHC's //de facto// mechanism for
 expressing higher-kinded roles, has landed. As such, I'll opt to close
 this ticket, as we can now express the sorts of programs that this ticket
 originally desired.

 Some has expressed the desire for the ability to encode this information
 into the roles system itself, but there doesn't appear to be a clear
 roadpath to doing so at the moment. As such, I don't think we need to keep
 this issue open. (If someone //does// think of a way to encode higher-
 kinded roles into the roles system, I'd encourage them to open a new
 ticket.)

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9123#comment:57>
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