[GHC] #1236: System.Mem.Weak breaks referential transparency

[GHC]

#1236: System.Mem.Weak breaks referential transparency
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 Reporter:  drtomc at gmail.com  |          Owner:         
     Type:  bug               |         Status:  closed 
 Priority:  normal            |      Milestone:         
Component:  libraries/base    |        Version:  6.6    
 Severity:  normal            |     Resolution:  invalid
 Keywords:                    |     Difficulty:  Unknown
 Testcase:                    |   Architecture:  Unknown
       Os:  Unknown           |  
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Changes (by simonmar):

  * resolution:  => invalid
  * status:  new => closed

Comment:

 `mkWeakPtr` does not break referential transparency.  You cannot use it to
 write a function that returns a non-deterministic result.

 Think of it as being similar to `forkIO`, in that it postpones an `IO`
 action until some time in the future.  This is one of the reasons that
 `mkWeakPtr` must be in the `IO` monad, incedentally.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1236>
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