[GHC] #8809: Prettier error messages?

[GHC]

#8809: Prettier error messages?
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        Reporter:  joelteon          |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.9
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
  #8809,#10073,#10179,#12906         |
       Wiki Page:                    |
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Comment (by mpickering):

 I'm a bit confused about the status of this ticket. The original poster
 suggests adding carets to error messages, this has now been done but the
 discussion in the ticket has moved all over the place. I want to bring
 order to the chaos!

 I think a new ticket which focuses just on the issue of adding semantic
 information to error messages should be created. There should also be
 (dare I say it...) a wikipage which outlines the suggested designs on this
 ticket.

 Richard, great that your student wants to work on this. Is that still the
 plan? Could she perhaps take care of creating the new ticket and the
 wikipage if she decides to take ownership of this. I entered this ticket
 with the intention to do so but don't want to step on her toes.


 When I last looked at this it seemed that the main problem was  #10735
 which talks about the problems with `pretty` which have so far put
 everyone off working on this (me included). The crux of the matter is that
 `pretty` isn't very efficient and we use it in the code generator. The
 solution here seems to be to use a different (simpler) pretty printing
 library for code generation as this shouldn't require complicated layout
 instructions such as hanging or nesting.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8809#comment:47>
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