[GHC] #12404: Document version availability for each language extension

[GHC]

#12404: Document version availability for each language extension
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        Reporter:  dfeuer            |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:  8.2.1
       Component:  Documentation     |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Documentation     |  Unknown/Multiple
  bug                                |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by dfeuer):

 Replying to [comment:1 thomie]:
 > Fwiw, there is [wiki:LanguagePragmaHistory].

 Imitation is the sincerest form of flattery. I think this is something
 that belongs in the GHC documentation proper. And that list does not (yet)
 include many details on changes made to the extensions from version to
 version. There have been some wobbles around `PolyKinds`, for example,
 although I don't know the details, and several changes to
 `PatternSynonyms` from 7.8 to 8.0.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12404#comment:2>
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