[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:
             Test Case:              |
              Blocking:              |
Differential Revisions:  Phab:D209   |
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Comment (by Herbert Valerio Riedel <hvr@…>):

 In [changeset:"eae19112462fe77a3f1298bff12b409b205a581d/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="eae19112462fe77a3f1298bff12b409b205a581d"
 Move `when` to GHC.Base

 This allows several modules to avoid importing Control.Monad and thus
 break
 import cycles that manifest themselves when implementing #9586

 Reviewed By: austin, ekmett

 Differential Revision: https://phabricator.haskell.org/D222
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9586#comment:7>
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