[GHC] #10457: Revise/remove custom mapM implementation for lists

[GHC]

#10457: Revise/remove custom mapM implementation for lists
-------------------------------------+-------------------------------------
        Reporter:  dolio             |                   Owner:
            Type:  task              |                  Status:  patch
        Priority:  normal            |               Milestone:  7.12.1
       Component:  libraries/base    |                 Version:  7.10.1
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:  Phab:D1124
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"60297486fddd5c9695e2263c2ae46fa90f0feb9e/ghc"
 60297486/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="60297486fddd5c9695e2263c2ae46fa90f0feb9e"
 Drop custom mapM impl for []

 See https://mail.haskell.org/pipermail/libraries/2015-May/025708.html
 for motivation.

 This fixes #10457

 Test Plan: Validate

 Reviewers: hvr, austin

 Subscribers: simonmar, thomie, dolio

 Differential Revision: https://phabricator.haskell.org/D1124

 GHC Trac Issues: #10457
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10457#comment:14>
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