[GHC] #14112: bang patterns on pattern synonyms? (left vs right hand sides)

[GHC]

#14112: bang patterns on pattern synonyms? (left vs right hand sides)
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        Reporter:  carter            |                Owner:  RyanGlScott
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.2.1
      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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Changes (by RyanGlScott):

 * owner:  (none) => RyanGlScott
 * milestone:   => 8.4.1


Comment:

 The only reason I don't favor (B) is because it's not always clear how
 you'd translate bang patterns on the RHS of an implicitly bidirectional
 pattern synonym to bang patterns for the builder arguments. For example,
 how would this be desugared?

 {{{#!hs
 pattern Foo a = Just !(Just a)
 }}}

 The only sensible thing I could envision here would be to silently ignore
 the bang pattern, but that makes me just as uncomfortable as it does you.

 I'd be willing to implement option (A).

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14112#comment:6>
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