[GHC] #13875: ApplicativeDo desugaring is lazier than standard desugaring

[GHC]

#13875: ApplicativeDo desugaring is lazier than standard desugaring
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        Reporter:  dfeuer            |                Owner:  simonmar
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  8.3
      Resolution:                    |             Keywords:  ApplicativeDo
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Other             |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by simonpj):

 * owner:  (none) => simonmar


Comment:

 It's a subtle issue, not described in the paper.  So yes we need something
 in the user manual, but a longer Note somewhere, linking to this ticket,
 giving example(s), and explaining our design choice, would be helpful.

 > To fix this properly we would have to prevent ApplicativeDo from
 applying to any statement with a strict pattern match.

 That would not be hard, would it?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13875#comment:4>
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