[GHC] #15930: Add @since-annotations to the Foldable methods

[GHC]

#15930: Add @since-annotations to the Foldable methods
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        Reporter:  sjakobi           |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:  8.6.3
       Component:  Core Libraries    |              Version:  8.6.2
      Resolution:                    |             Keywords:  newcomers
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by RyanGlScott):

 * keywords:   => newcomers


Comment:

 Indeed. Based on my testing (i.e., [https://github.com/nfrisby/invariant-
 functors/blob/ed51d2f0343c060076672e41f588447a179babda/src/Data/Functor/Invariant.hs#L581-L594
 here]), we need the following `@since` annotations:

 * Introduced in `base-4.6.0.0`:
   * `foldr'`
   * `foldl'`
 * Introduced in `base-4.8.0.0`:
   * `toList`
   * `null`
   * `length`
   * `elem`
   * `maximum`
   * `minimum`
   * `sum`
   * `product`

 Any volunteers?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15930#comment:1>
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