[GHC] #9510: Prelude.!! is not a good consumer

[GHC]

#9510: Prelude.!! is not a good consumer
-------------------------------------+-------------------------------------
              Reporter:  dfeuer      |            Owner:  ekmett
                  Type:  bug         |           Status:  patch
              Priority:  normal      |        Milestone:
             Component:  Core        |          Version:  7.8.3
  Libraries                          |         Keywords:  fusion
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Unknown
  Unknown/Multiple                   |       Blocked By:
       Type of failure:  Runtime     |  Related Tickets:
  performance bug                    |
             Test Case:              |
              Blocking:              |
Differential Revisions:  Phab:D380   |
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Comment (by Herbert Valerio Riedel <hvr@…>):

 In [changeset:"75979f3661ff16ec44528a23005ac1be2b9683fe/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="75979f3661ff16ec44528a23005ac1be2b9683fe"
 base: Refactor/clean-up *List modules

 This gets rid of all hand-unboxing in `GHC.List` and moves `Foldable`
 requirements from `Data.OldList` into `GHC.List` (preparatory work for
 addressing #9716).  Specifically, this moves the definition of
 `maximum`, `minimum`, `foldl'`, `foldl1`, `foldl1'`, `sum`, and
 `product` into `GHC.List` (which now needs to import `GHC.Num`)

 Make `take`, `drop`, `length`, and `!!` generally saner (see also #9510)

 Performance overall seems minimally affected. Some things go up; some
 things go down; nothing moves horribly much. The code is much easier to
 read.

 Differential Revision: https://phabricator.haskell.org/D380
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9510#comment:4>
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