[GHC] #8185: Change role annotation syntax

[GHC]

#8185: Change role annotation syntax
----------------------------+----------------------------------------------
        Reporter:           |            Owner:  goldfire
  goldfire                  |           Status:  new
            Type:  feature  |        Milestone:  7.8.1
  request                   |          Version:  7.7
        Priority:  normal   |         Keywords:
       Component:           |     Architecture:  Unknown/Multiple
  Compiler                  |       Difficulty:  Moderate (less than a day)
      Resolution:           |       Blocked By:
Operating System:           |  Related Tickets:
  Unknown/Multiple          |
 Type of failure:           |
  None/Unknown              |
       Test Case:           |
        Blocking:           |
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Comment (by goldfire):

 Yes, very much agreed with rwbarton:

 {{{
 data Foo {-# ROLE Nominal #-} a = ...
 }}}

 is the plan for labeling `a` with role `Nominal`.

 Also as part of this plan is to prefer writing out role names in full
 (e.g., "Nominal" not "N") to help with understanding and searching.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8185#comment:3>
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