[GHC] #9628: Add Annotations to the AST to simplify source to source conversions

[GHC]

#9628: Add Annotations to the AST to simplify source to source conversions
-------------------------------------+-------------------------------------
              Reporter:  alanz       |            Owner:  alanz
                  Type:  feature     |           Status:  new
  request                            |        Milestone:
              Priority:  normal      |          Version:  7.8.3
             Component:  Compiler    |         Keywords:
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Unknown
  Unknown/Multiple                   |       Blocked By:
       Type of failure:              |  Related Tickets:
  None/Unknown                       |
             Test Case:              |
              Blocking:              |
Differential Revisions:  D246        |
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Comment (by simonpj):

 I'm afraid I'm very confused by this thread.

  * There are two different Phab tickets: Phab:D246 is linked to this
 ticket, but Phab:D297 (I believe) may supercede it.  If so please let's
 redirect the "Differential revision" field of this ticket, and explicit
 mark the moribund one as moribund.

  * The wiki page GhcAstAnnotations does not appear to reflect any of the
 discussion.  Indeed it appears to describe only the first bullet from
 comment:3

  * comment:3 identifies two issues, which Alan (in comment:4) agreed were
 separate. Yet [http://www.haskell.org/pipermail/ghc-
 devs/2014-October/006487.html Neil certainly thinks] that the new
 Phab:D297 is exclusively about issue 1.  So maybe the new design
 encompasses both issue 1 and issue 2?  I have no idea.

  * There has been quite a lot of [http://www.haskell.org/pipermail/ghc-
 devs/2014-October/006482.html traffic on ghc-devs] that is not captured
 anywhere.  That's fine: an email list is good for discussion.  But my
 input bandwidth is low and struggle to make sense of it all. And the
 conclusions from the discussion may be useful.

  * Alan has posted a [http://www.haskell.org/pipermail/haskell-
 cafe/2014-October/116267.html useful summary] to Haskell Cafe, which isn't
 captured on a wiki anywhere.

  * Alan has done some work identifying users for the new features, and
 written some email notes about that; again this would be useful to
 capture.

 I am too slow to take a big patch and try to reverse-engineer the thought
 process that went into it.  Would be possible to update the wiki page
 (presumably GhcAstAnnotations) to state
  * The problem we are trying to solve
  * The user-visible (or at least visible-to-client-of-GHC-API) design
  * Other notes about the implementation.

 Covering the larger picture about the GHC API improvements you are making
 (eg no landmines) would be helpful.  Maybe you need more than one page.

 I'm delighted you are doing this.  But I don't want to throw a lot of code
 into GHC without a clear, shared consensus about what it is we are trying
 do to, and how we are doing it.

 Thanks.

 Simon (drowning in review requests) PJ

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9628#comment:12>
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