[GHC] #8345: A more efficient atomicModifyIORef'

[GHC]

#8345: A more efficient atomicModifyIORef'
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              Reporter:  parcs       |            Owner:
                  Type:  bug         |           Status:  new
              Priority:  normal      |        Milestone:  7.10.1
             Component:              |          Version:  7.6.3
  libraries/base                     |         Keywords:  IORef
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Moderate (less
  Unknown/Multiple                   |  than a day)
       Type of failure:  Runtime     |       Blocked By:
  performance bug                    |  Related Tickets:  #5926
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Changes (by hvr):

 * cc: ekmett (added)


Comment:

 Just a thought, what about:

 {{{#!hs
 atomicModifyIORef' ref f =
     evaluate =<< atomicModifyIORef ref (\a -> case f a of v@(!a',_) -> v)
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8345#comment:4>
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