[GHC] #10344: Make BranchList simpler

[GHC]

#10344: Make BranchList simpler
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        Reporter:  goldfire          |                   Owner:  goldfire
            Type:  task              |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.11
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:
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Comment (by goldfire):

 But looking at Adam's code, I think changing it from using `Maybe` would
 make it more complex, not less. (I agreed with you about avoiding `Maybe`
 here originally, but inspection of the code encouraged me to change my
 mind.)

 In any case, I don't feel too strongly here. Ask once more, and I'll agree
 with you. :)

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10344#comment:5>
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