[GHC] #9527: Add Generic instances for Language.Haskell.TH

[GHC]

#9527: Add Generic instances for Language.Haskell.TH
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              Reporter:  nh2         |            Owner:  goldfire
                  Type:  feature     |           Status:  new
  request                            |        Milestone:  7.10.1
              Priority:  normal      |          Version:  7.8.3
             Component:  Core        |         Keywords:
  Libraries                          |     Architecture:  Unknown/Multiple
            Resolution:              |       Difficulty:  Moderate (less
      Operating System:              |  than a day)
  Unknown/Multiple                   |       Blocked By:  9526
       Type of failure:              |  Related Tickets:
  None/Unknown                       |
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Comment (by goldfire):

 An IRC discussion suggests not adding `Binary` instances:

 hvr
 1:32 goldfire: well, we only recently dropped the containers dep in
 template-haskell to not force users wanting to use TH to a specific
 containers verison
 hvr
 1:32 goldfire: adding  dep on 'binary' would be rather undesirable in that
 respect
 goldfire
 1:32 hvr: That makes sense.
 1:33 hvr: Does this get mitigated at all by the Backpack work?
 hvr
 1:33 goldfire: no idea tbh
 goldfire
 1:33 Because my (very loose) understanding is that multiple versions of
 the same package can now coexist peacefully.
 1:34 So, a TH client that doesn't use the Binary instances would be
 welcome to use a different version of the binary package.
 1:34 But, a TH client that wanted to use the TH Binary instances would be
 tied to the specific version of binary that TH ships with, lest they get
 type errors.
 1:35 ezyang: Care to comment on my and hvr's discussion just now?
 ezyang
 1:46 goldfire, hvr: As with everything, this comes with the caveat that
 Cabal doesn't know how to handle this, but yes, in principle this is
 possible with the new change
 rwbarton
 1:47 sounds like it would make sense to wait until 7.12 to add those
 instances
 goldfire
 1:47 rwbarton: Yes, that's the conclusion I'm coming to. luite: Care to
 counter?
 rwbarton
 1:48 since the out-of-process TH most likely won't land in 7.10 anyways
 right?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9527#comment:5>
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