[GHC] #9531: Implement Prelude.Word Proposal

[GHC]

#9531: Implement Prelude.Word Proposal
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              Reporter:  hvr         |            Owner:  hvr
                  Type:  task        |           Status:  new
              Priority:  normal      |        Milestone:  7.10.1
             Component:              |          Version:
  libraries/base                     |         Keywords:  Prelude
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Easy (less than 1
  Unknown/Multiple                   |  hour)
       Type of failure:              |       Blocked By:
  None/Unknown                       |  Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Comment (by Herbert Valerio Riedel <hvr@…>):

 In [changeset:"393b820233caa00e428affc28e090b496d181664/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="393b820233caa00e428affc28e090b496d181664"
 Re-export Word from Prelude (re #9531)

 The original proposal text can be found at

   http://www.haskell.org/pipermail/libraries/2014-August/023491.html

 The proposal passed with a clear majority, and was additionally
 confirmed by the core libraries committee.

 *Compatibility Note*

 Only code that imports `Data.Word` for the sole purpose of using `Word`
 *and* requires to be `-Werror`-clean (due to `-fwarn-unused-imports`)
 is affected by this change.

 In order to write warning-free forward/backward compatible against `base`,
 a variant of the following CPP-based snippet can be used:

   -- Starting with base>4.7.0 or GHC>7.8 Prelude re-exports 'Word'
   -- The following is needed, if 'Word' is the *only* entity needed from
 Data.Word
   #ifdef MIN_VERSION_base
   # if !MIN_VERSION_base(4,7,1)
   import Data.Word (Word)
   # endif
   -- no cabal_macros.h -- fallback to __GLASGOW_HASKELL__
   #elif __GLASGOW_HASKELL__ < 709
   import Data.Word (Word)
   #endif

 This also updates the haddock submodule in order to avoid a compile
 warning
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9531#comment:1>
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