[GHC] #9590: AMP breaks `haskell2010` package

[GHC]

#9590: AMP breaks `haskell2010` package
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              Reporter:  hvr         |            Owner:
                  Type:  bug         |           Status:  new
              Priority:  high        |        Milestone:  7.10.1
             Component:              |          Version:  7.9
  libraries/haskell2010              |         Keywords:  AMP
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Unknown
  Unknown/Multiple                   |       Blocked By:
       Type of failure:  GHC         |  Related Tickets:
  rejects valid program              |
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Comment (by ekmett):

 It is a bit more complex than just pasting the report. GHC internals
 actually know where `Monad` comes from for instance, so you'd have knock-
 on consequences.

 If we `do` adopt a `haskell2010` fully standards compliant package:

 1.) We'd need to make some modifications to GHC itself to tell it where to
 desugar to for the `Monad` syntax and internal hackery. We'd need to
 figure out how to tell tools like cabal to do the right thing.

 2.) Code that previously worked with the `haskell2010` or `haskell98`
 packages would cease to work with `base` and vice versa where those
 instances are concerned. You'd be giving up, say, `containers`, not just
 the rest of `base`. This actually comes at a price to a dozen or two
 packages that are built right now with the `haskell98` package and with
 these other dependencies as well, possibly breaking in non-obvious ways.

 It may be that to fully support both of these two very different usecases
 for `haskell2010` that you'd get two `haskell2010`-like packages to
 support both user pools.

 This makes for a very complex story to explain to end users, and a lot of
 engineering.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9590#comment:7>
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