[GHC] #13104: runRW# ruins join points

[GHC]

#13104: runRW# ruins join points
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        Reporter:  lukemaurer        |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.1
      Resolution:                    |             Keywords:  JoinPoints
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by nomeata):

 This wouldn’t be a valid use of a join point, would it? You cannot pass
 join-points in lambdas to arguments.

 But maybe that points to a solution. Can we somehow tell GHC that the
 argument of `runRW#` is special in the sense that passing a join-point
 call there is ok? So to say, a promise that by the time we generate code,
 the argument will be passed `n` functions and be used in a join-point
 eligible way?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13104#comment:8>
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