[GHC] #13330: forkIO has inconsistent behavior under optimization

[GHC]

#13330: forkIO has inconsistent behavior under optimization
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        Reporter:  dfeuer            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.2.1
       Component:  Core Libraries    |              Version:  8.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Other             |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D3189
       Wiki Page:                    |
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Comment (by dfeuer):

 Replying to [comment:15 simonpj]:
 > Demand signatures are not expressive enough to express the either/or
 demand you want in comment:14.  Sorry.  Not even close.
 >
 > My questions in comment:13 stand though.  What goes wrong (in behavior
 or perf) if we just say `catchException = catch`?

 I haven't tried `catchException = catch` yet. I'll take a look at that
 soon. Are you sure demand signatures aren't close to expressive enough for
 what I want? Because they ''look'' fairly close. We have a way to talk
 about either-or demand for `case` branches. We have something fairly close
 to

 {{{#!hs
 m `catch#` f = \s -> case ORACLE m s of
   Succeeded -> m s
   Failed e -> f e s
 }}}

 If we're analyzing ``m `catch#` f``, can't we find the demands for `m`
 applied to one argument and for `f` applied to two? Because then we can
 take their least upper bound and get demands for the whole thing applied
 to the `realWorld#`, right? That doesn't give `catch#` itself a terribly
 demand signature, but it shouldn't matter.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13330#comment:16>
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