[GHC] #9586: Implement Traversable/Foldable-Burning-Bridges Proposal

[GHC]

#9586: Implement Traversable/Foldable-Burning-Bridges Proposal
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              Reporter:  hvr         |            Owner:  hvr
                  Type:  task        |           Status:  new
              Priority:  normal      |        Milestone:  7.10.1
             Component:              |          Version:
  libraries/base                     |         Keywords:
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Difficult (2-5
  Unknown/Multiple                   |  days)
       Type of failure:              |       Blocked By:
  None/Unknown                       |  Related Tickets:  #9621
             Test Case:              |
              Blocking:              |
Differential Revisions:  Phab:D209   |
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Comment (by Herbert Valerio Riedel <hvr@…>):

 In [changeset:"5ed12810e0972b1e0d408fe1355805746c4614f9/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="5ed12810e0972b1e0d408fe1355805746c4614f9"
 Move `mapM` and `sequence` to GHC.Base and break import-cycles

 This simplifies the import graph and more importantly removes import
 cycles that arise due to `Control.Monad` & `Data.List` importing
 `Data.Traversable` (preparation for #9586)

 Reviewed By: ekmett, austin

 Differential Revision: https://phabricator.haskell.org/D234
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9586#comment:17>
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