[GHC] #7582: Created thunk gets immediately evaluated

[GHC]

#7582: Created thunk gets immediately evaluated
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  Reporter:  tibbe             |          Owner:                  
      Type:  bug               |         Status:  closed          
  Priority:  normal            |      Milestone:                  
 Component:  Compiler          |        Version:  7.6.1           
Resolution:  invalid           |       Keywords:                  
        Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
   Failure:  None/Unknown      |     Difficulty:  Unknown         
  Testcase:                    |      Blockedby:                  
  Blocking:                    |        Related:                  
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Changes (by simonpj):

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


Comment:

 Yes, consider `(lookup undefined `seq` True)`.  In your original program
 this should yield `True`. When you add the bang on `h0` you change the
 semantics so that the expression yields `undefined`.  Different semantics,
 different code.  I don't see how to get better behaviour while preserving
 semantics.  Please re-open if you can see a way.

 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7582#comment:2>
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