[GHC] #9502: mapAccumL does not participate in foldr/build fusion

[GHC]

#9502: mapAccumL does not participate in foldr/build fusion
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       Reporter:  dfeuer             |                   Owner:
           Type:  bug                |                  Status:  new
       Priority:  normal             |               Milestone:
      Component:  libraries/base     |                 Version:  7.8.3
       Keywords:                     |        Operating System:
   Architecture:  Unknown/Multiple   |  Unknown/Multiple
     Difficulty:  Unknown            |         Type of failure:  Runtime
     Blocked By:                     |  performance bug
Related Tickets:                     |               Test Case:
                                     |                Blocking:
                                     |  Differential Revisions:
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 This can probably be fixed in much the same way as `scanl`.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9502>
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