[Haskell-cafe] ANN: unordered-containers - a new, faster hashing-based containers library

[Max Bolingbroke]

On 20 February 2011 03:40, Louis Wasserman <wasserman.louis at gmail.com> wrote:
> I'd like to complain about that, too ;)

I'm curious, when do people find that they need a really fast way to
get map size? I use them quite a lot, and almost never call length -
and when I do, it is typically only to get some statistics about the
map for user display - certainly not in an inner loop.

I find it is still useful to have a way to quickly test if a map is
empty (for e.g. fixed points that slowly grow a map by unioning in a
new bit every time) but "null" works OK for that purpose.

Cheers,
Max