[GHC] #5930: add System.Environment.lookupEnv which returns Maybe instead of an exception

[GHC]

#5930: add System.Environment.lookupEnv which returns Maybe instead of an
exception
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 Reporter:  elaforge          |          Owner:                  
     Type:  feature request   |         Status:  patch           
 Priority:  normal            |      Component:  libraries/base  
  Version:  7.4.1             |       Keywords:                  
       Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
  Failure:  None/Unknown      |       Testcase:                  
Blockedby:                    |       Blocking:                  
  Related:                    |  
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Comment(by Lemming):

 Discussion started here:
 http://www.haskell.org/pipermail/libraries/2012-February/017576.html

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5930#comment:2>
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