[GHC] #15532: Relaxing Levity-Polymorphic Binder Check for Lifted vs Unlifted pointers

[GHC]

#15532: Relaxing Levity-Polymorphic Binder Check for Lifted vs Unlifted pointers
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        Reporter:  andrewthad        |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.4.3
      Resolution:                    |             Keywords:
                                     |  LevityPolymorphism
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  14917             |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by andrewthad):

 So, you couldn't write `map` or `foldr` or anything like that, but you
 could get a levity polymorphic index lookup:

 {{{
 (!) :: forall (v :: Levity) (a :: TYPE ('PtrRep v)). Int -> List a -> a
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15532#comment:12>
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