[GHC] #10190: Add a Monad instance for ((,) w)

[GHC]

#10190: Add a Monad instance for ((,) w)
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        Reporter:  fumieval          |                   Owner:  fumieval
            Type:  feature request   |                  Status:  patch
        Priority:  normal            |               Milestone:  7.12.1
       Component:  libraries/base    |                 Version:
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:
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Comment (by Herbert Valerio Riedel <hvr@…>):

 In [changeset:"9db005a444722e31aca1956b058e069bcf3cacbd/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="9db005a444722e31aca1956b058e069bcf3cacbd"
 Add Monad instance for `((,) a)` (#10190)

 This was proposed a couple of times in the past, e.g.

  - https://mail.haskell.org/pipermail/libraries/2011-November/017153.html
  - https://mail.haskell.org/pipermail/libraries/2013-July/020446.html

 but its implementation had been blocked by the fact that `Monoid` wasn't
 in scope where the `Monad` class was defined. Since the AMP/FTP
 restructuring
 this is no longer the case.
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10190#comment:9>
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