[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:  closed
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:  fixed             |             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 simonpj):

 OK that's good!  I still don't know ''why'' the effect is so large; but
 there was a definite bug, now fixed by the "tiny refactor".  Which was not
 as tiny as I thought.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13227#comment:23>
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