[GHC] #2580: export Data.Map.toDescList

[GHC]

#2580: export Data.Map.toDescList
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    Reporter:  elaforge        |        Owner:  igloo  
        Type:  proposal        |       Status:  new    
    Priority:  normal          |    Milestone:         
   Component:  libraries/base  |      Version:  6.8.3  
    Severity:  normal          |   Resolution:         
    Keywords:                  |     Testcase:         
Architecture:  Unknown         |           Os:  Unknown
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Changes (by elaforge):

  * owner:  => igloo

Comment:

 Replacing patch yet again to export foldrWithKey also.

 Summary from the "thread" such as it was:

 Benedikt suggested adding something like:
 > viewAssocs :: Map k v -> MapView (k,v)
 > instance Foldable MapView

 This might be a good idea for the future but I wanted to keep the scope of
 the patch under control.

 On further thought, it seemed asymmetrical to export foldWithKey and
 foldlWithKey, so I added foldrWithKey to the export list, keeping
 foldWithKey to not break existing code.  I added a note to the haddock for
 foldWithKey encouraging the use of foldrWithKey.

 So we export:
 toDescList - new, but implementable with foldlWithKey
 foldlWithKey - new
 foldrWithKey - the same as foldWithKey, but explicitly the mirror of
 foldlWithKey

 There were no other comments.  I'm specifically not certain about the
 laziness of the folds (i.e. will they lead to stack problems like
 List.foldl), but no one said there was a problem, so maybe it's fine.  I'm
 also not sure if there was some important reason behind the reason the
 folds were exported, but no one said anything, so maybe it was just
 arbitrary.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2580#comment:2>
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