[GHC] #10755: Add `MonadPlus IO` and `Alternative IO` instances

[GHC]

#10755: Add `MonadPlus IO` and `Alternative IO` instances
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        Reporter:  hvr               |                Owner:
            Type:  task              |               Status:  patch
        Priority:  normal            |            Milestone:  8.0.1
       Component:  Core Libraries    |              Version:
      Resolution:                    |             Keywords:  report-impact
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1148
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Comment (by Austin Seipp <austin@…>):

 In [changeset:"b62605e53c167719b3bf8842eba628061cf22dd1/ghc"
 b62605e5/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="b62605e53c167719b3bf8842eba628061cf22dd1"
 Add `MonadPlus IO` and `Alternative IO` instances

 This requires adding a new primitive `mplusIO` to `GHC.IO`

 Update transformers submodule to accomodate extant orphan instances.

 Reviewed By: austin, bgamari

 Differential Revision: https://phabricator.haskell.org/D1148

 GHC Trac Issues: #10755
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10755#comment:12>
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