[GHC] #13547: Lint error in arrows program

[GHC]

#13547: Lint error in arrows program
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        Reporter:  cipher1024        |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
  (CodeGen)                          |
      Resolution:                    |             Keywords:  Arrows
Operating System:  Unknown/Multiple  |         Architecture:  x86_64
 Type of failure:  Compile-time      |  (amd64)
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  10158             |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by simonpj):

 * cc: simonmar (removed)
 * cc: Henrik.Nilsson@…, Ross, Paterson, <ross@…> (added)


Comment:

 Thanks for boiling it down so much futher.

 I have only the vaguest idea about how arrow-desugaring works, but I think
 it's very likely that it won't work at all if there are existentials
 involved.  Would an arrow expert care to give an opinion?  Henrik?  Ross?

 If so, we should reject it in a civilised way, not crash.

 Generally, arrows are sorely in need of love.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13547#comment:29>
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