[GHC] #8818: Add withMVarMasked

[GHC]

#8818: Add withMVarMasked
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        Reporter:  hvr               |            Owner:  hvr
            Type:  feature request   |           Status:  new
        Priority:  normal            |        Milestone:  7.10.1
       Component:  libraries/base    |          Version:
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by Herbert Valerio Riedel <hvr@…>):

 In [changeset:"2d5471cd3ee42406042a030424a1a83308a170fa/base"]:
 {{{
 #!CommitTicketReference repository="base"
 revision="2d5471cd3ee42406042a030424a1a83308a170fa"
 Add `withMVarMasked` (re #8818)

 Like `withMVar`, but the @IO@ action in the second argument is executed
 with asynchronous exceptions masked. This completes the `MVar` API,
 which already contained `modifyMVarMasked` and `modifyMVarMasked_`.

 Signed-off-by: Herbert Valerio Riedel <hvr at gnu.org>
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8818#comment:1>
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