[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
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              Reporter:  alanz       |            Owner:  alanz
                  Type:  feature     |           Status:  new
  request                            |        Milestone:
              Priority:  normal      |          Version:  7.9
             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:  D297        |
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Comment (by simonpj):

 I suggest doing so only if the two can differ.  In the case of `String`
 there can be string gaps, thus
 {{{
 foo :: String
 foo = "blah blah\
       \more blah blah\
       \and more"
 }}}
 and I guess you want to have all that layout reproduced. Fine.  But for
 integers like `3234242329423`, I don't see how the displayed form could
 differ.

 For `Words` perhaps there is binary/hex forms?

 Regardless, I'm not against this, but very keen that the reasons for
 keeping the two are documented on a per-literal basis, as I have begun to
 do above.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9628#comment:29>
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