[GHC] #15219: Implement UnliftedNewtypes proposal

[GHC]

#15219: Implement UnliftedNewtypes proposal
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        Reporter:  andrewthad        |                Owner:  (none)
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Compiler          |              Version:  8.4.3
      Resolution:                    |             Keywords:
                                     |  UnliftedNewtypes, GHCProposal
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 LeanderK):

 Question: Would it be possible to introduce UnliftedNewtypes in one of the
 following releases (something like 8.6.3?)?

 I have a use-case where levity-polymorphism would help, but it crucially
 relies on having levity polymorphic newtypes.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15219#comment:4>
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