[GHC] #13227: Loss of full laziness in mapFB

[GHC]

#13227: Loss of full laziness in mapFB
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        Reporter:  simonpj           |                Owner:  nomeata
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D3067
       Wiki Page:                    |
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Comment (by nomeata):

 I gave it a shot, but something is clearly still wrong, I get huge
 regressions in performance tests. I will try counting only the length of
 the `OneShot` prefix of `occ_one_shots` (which seems to make more sense to
 me).

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13227#comment:14>
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