[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 simonpj):

 That's ok with me.

   So all we are left with is the choice about whether to support
 {{{
 {-# ROLE Map nominal representational #-}
 }}}
 as alternative syntax for those who want to use a noisier syntax that
 allows the same module to be compiled with older role-ignorant GHCs,
 without #ifdefs.  Personally I think that an #ifdef is clearer.

 Simon

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8185#comment:12>
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