[GHC] #12243: RebindableSyntax and OverloadedLabels

[GHC]

#12243: RebindableSyntax and OverloadedLabels
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        Reporter:  htebalaka         |                Owner:  adamgundry
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:  ORF
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 adamgundry):

 * owner:   => adamgundry
 * milestone:   => 8.2.1


Comment:

 A
 [https://www.reddit.com/r/haskell/comments/4x8tk8/overloadedlabels_considered_awesome/d6jg78i
 reddit discussion] made me realise that there are some use cases for this.
 In particular, the translation of overloaded labels to `IsLabel` may
 introduce ambiguous type variables, which could be avoided using a more
 restrictive `fromLabel` (e.g. constraining it to be a field selector, one
 we have `OverloadedRecordFields`). Essentially, rebindable syntax makes it
 possible to choose a single `IsLabel` instance for an entire module.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12243#comment:2>
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