[GHC] #7828: RebindableSyntax and Arrow

[GHC]

#7828: RebindableSyntax and Arrow
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        Reporter:  AlessandroVermeulen        |            Owner:
            Type:  bug                        |  jstolarek
        Priority:  normal                     |           Status:  new
       Component:  Compiler (Type checker)    |        Milestone:  7.10.1
      Resolution:                             |          Version:  7.6.2
Operating System:  Unknown/Multiple           |         Keywords:
 Type of failure:  GHC rejects valid program  |     Architecture:
       Test Case:                             |  Unknown/Multiple
        Blocking:                             |       Difficulty:  Unknown
                                              |       Blocked By:
                                              |  Related Tickets:
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Comment (by simonpj):

 Well in principle with rebindable syntax, each of those calls to `>>>` at
 different types (I assume they are at different types?) could in principle
 be overloaded a different way.  So
  * There really is no alternative to generating them all
  * I really don't know what sort of error message you'd generate for the
 user if one of the calls to `>>>` failed but the others didn't, say.

 Before going further I think we need help from Ross, to see if the
 "thought experiment of desugar and then typecheck" makes sense for arrows.
 We MUST give a clear story to the programmer of what will type check and
 what will not.  We have that for rebindable syntax and do-notation.  I
 don't know what the story is for rebindable syntax and arrow notation.
 Until we know that we can't implement anything.

 > What do you think about the design I describe above?

 What precisely is "above".  I don't see a proposed design.

 We really need help from Ross here.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7828#comment:10>
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