[GHC] #973: Adding Arbitrary instance for Either

[GHC]

#973: Adding Arbitrary instance for Either
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 Reporter:  guest              |          Owner:         
     Type:  proposal           |         Status:  new    
 Priority:  normal             |      Milestone:         
Component:  libraries (other)  |        Version:  6.6    
 Severity:  normal             |     Resolution:         
 Keywords:                     |     Difficulty:  Unknown
 Testcase:                     |   Architecture:  Unknown
       Os:  Unknown            |  
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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/973>
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