Add bloom filters to standard library.

[eholk]

This would be a handy thing to have.

[benbrittain]

working on it

[eholk]

It looks like the Bloom filter is now a cargo package.

https://github.com/mozilla/cargo-central/commit/cf28beaa46bcd0c06bd7741d9322670c47754039

I'll go ahead and close this bug, although maybe we'll want to move the Bloom filter into libstd sometime.

[bstrie]

Reopening this since eholk's link is dead, and I feel that this is the sort of thing that at least deserves a place in libextra.

Here's an implementation we could perhaps think of adopting:

https://github.com/jedisct1/rust-bloom-filter

...which was mentioned in this blog post:

http://labs.umbrella.com/2013/10/04/zeromq-helping-us-block-malicious-domains/

...which was brought to my attention by @pcwalton. Perhaps he's already given the code a once-over, and can comment on its quality?

[bstrie]

Nominating for Feature Complete milestone.

[thestinger]

Another repository to keep an eye on: https://github.com/polyfractal/rust-approx

[thestinger]

I don't think this needs to be nominated. It would be nice to have but I don't know a language shipping one in the standard library, and it wouldn't be a very commonly used data structure.

[thestinger]

Since extra is going away, I think this should remain as an external package. It doesn't seem like a strong candidate for libstd as it's not going to be widely used.