[GHC] #11815: Data.List: Add a function to get consecutive elements (mapConsecutives)

[GHC]

#11815: Data.List: Add a function to get consecutive elements (mapConsecutives)
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        Reporter:  holmisen          |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  low               |            Milestone:
       Component:  libraries/base    |              Version:
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by dfeuer):

 For educational porpoises, note that GHC is quite good at recognizing that
 the recursive call always receives a `Just` value, so it can use a worker-
 wrapper transformation to avoid all the `Maybe` business. I don't know if
 the `seq` is strictly necessary here, but times I've left that out of
 similar forms I've ended up regretting it eventually.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11815#comment:7>
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