export toDescList from Data.Map

[Evan Laforge]

> Anyway, is 2-3 weeks ok for discussion period?  The library submission
> wiki doesn't say how long.

So it's been a little while and there hasn't been any objection.
What's the next step?  Is there any problem with applying the patch as
it stands and will it be in 6.10?  To re-recap, it exports toDescList,
and foldlWithKey.  I'm assuming its current level of strictness is ok
since no one has said anything.


As an aside, it's curious to me that so few people care about
Data.Map.  In my code, it's the #1 data structure, except for lists,
which almost all generated and consumed incrementally and thus take up
little space and have simple access patterns.  Data.Map does all the
heavy lifting.  Other people don't use it?