[GHC] #5902: Cannot tell from an exception handler whether the exception was asynchronous

[GHC]

#5902: Cannot tell from an exception handler whether the exception was
asynchronous
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        Reporter:  simonmar          |            Owner:  simonmar
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:  7.8.1
       Component:  Compiler          |          Version:  7.4.1
      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 igloo):

 Hmm. If we also had something like
 {{{
 newUnsafePerformIO :: IO a -> a
 newUnsafePerformIO io = unsafePerformIO io'
     where io' = io `newCatch` (\eb -> (newThrow eb >> io'))
 }}}
 so that at the outermost level the unsafePerformIO knows how to continue,
 then would that suffice? Or would it still be possible for problematic
 thunks inside `io` to be reentered?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5902#comment:13>
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