[GHC] #9671: Allow expressions in patterns

[GHC]

#9671: Allow expressions in patterns
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        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:
      Resolution:                    |             Keywords:
                                     |  PatternSynonyms
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 Iceland_jack):

 Replying to [comment:3 cactus]:
 > > The implementation is a straightforward desugaring into pattern
 synonyms and view patterns
 >
 > That's how I started the work on pattern synonyms in the first place...
 spoiler alert: it never is :)

 ;)

 > +1 to SPJ on distinguishing ''pat'' and ''expr'' arguments. In fact, I
 think they should be distinguished even when introducing them as formal
 arguments.

 Can you elaborate on last part

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9671#comment:12>
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