[GHC] #8158: Replace IO manager's IntMap with a mutable hash table

[GHC]

#8158: Replace IO manager's IntMap with a mutable hash table
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        Reporter:  bos         |            Owner:
            Type:  feature     |           Status:  patch
  request                      |        Milestone:  7.8.1
        Priority:  normal      |          Version:  7.7
       Component:              |         Keywords:
  libraries/base               |     Architecture:  Unknown/Multiple
      Resolution:              |       Difficulty:  Easy (less than 1 hour)
Operating System:              |       Blocked By:
  Unknown/Multiple             |  Related Tickets:
 Type of failure:  Other       |
       Test Case:              |
        Blocking:              |
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Comment (by simonmar):

 @bos: GHC has a `FastMutInt` type for this purpose, which is a 1-element
 mutable unboxed array.  I'd be interested to know whether performance
 differs between this and `ForeignPtr`.

 source:ghc/compiler/utils/FastMutInt.lhs

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8158#comment:8>
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