[GHC] #9827: void does not use <$

[GHC]

#9827: void does not use <$
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              Reporter:  dfeuer      |            Owner:  dfeuer
                  Type:  task        |           Status:  patch
              Priority:  normal      |        Milestone:  7.10.1
             Component:  Core        |          Version:  7.9
  Libraries                          |         Keywords:
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Easy (less than 1
  Unknown/Multiple                   |  hour)
       Type of failure:  Runtime     |       Blocked By:
  performance bug                    |  Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:  Phab:D521   |
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Comment (by Herbert Valerio Riedel <hvr@…>):

 In [changeset:"cc7a735f015510dda6f69d4a48d1b0cdd55856ba/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="cc7a735f015510dda6f69d4a48d1b0cdd55856ba"
 Define void using <$ (re #9827)

 `() <$ x` is sometimes better than `fmap (const ()) x` and should
 never be worse.

 Reviewed By: ekmett

 Differential Revision: https://phabricator.haskell.org/D521
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9827#comment:2>
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