[GHC] #8026: DatatypeContexts should be fixed, not deprecated

[GHC]

#8026: DatatypeContexts should be fixed, not deprecated
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              Reporter:  gidyn       |            Owner:
                  Type:  feature     |           Status:  new
  request                            |        Milestone:
              Priority:  normal      |          Version:  7.6.3
             Component:  Compiler    |         Keywords:
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Unknown
  Unknown/Multiple                   |       Blocked By:
       Type of failure:              |  Related Tickets:
  None/Unknown                       |
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Comment (by simonpj):

 I urge you to read the OutsideIn(X) paper.

 I think that what you want in comment:21 is already fully implemented.
 You would declare `MVector` like this:
 {{{
 data MVector m a where
   MVector :: PrimMonad m
           => !Int -> !Int -> !(MutableArray (PrimState m) a) -> MVector m
 a
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8026#comment:22>
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