[GHC] #9337: Add `sortOn` function to Data.List

[GHC]

#9337: Add `sortOn` function to Data.List
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       Reporter:  JohnWiegley              |             Owner:
           Type:  feature request          |            Status:  closed
       Priority:  normal                   |         Milestone:  7.10.1
      Component:  libraries/base           |           Version:  7.8.3
     Resolution:  duplicate                |          Keywords:
   Differential:                           |  Operating System:
   Architecture:  Unknown/Multiple         |  Unknown/Multiple
     Difficulty:  Easy (less than 1 hour)  |   Type of failure:
     Blocked By:                           |  None/Unknown
Related Tickets:  #9004                    |         Test Case:
                                           |          Blocking:
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Changes (by hvr):

 * status:  new => closed
 * resolution:   => duplicate
 * related:   => #9004


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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9337#comment:6>
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