add pixie.walk

[mpenet]

It's very similar to clojure.walk but uses transients when possible, and is extensible via a protocol.

[thomasmulvaney]

I've restarted the build as it looks like pulling down deps failed.

[mpenet]

yep, the pypy archive is not available https://bitbucket.org/pypy/pypy/get/default.tar.bz2 returns an http 500 at the moment.

[mpenet]

I forgot to mention, this API doesn't include the "outer" fn parameter from the clojure equivalent, I never really understood why they baked in this fn, as you can just call it on the result returned by a walk yourself and seems to make things more confusing for little benefit.

Feel free to tell me if you think it's not ok.

[thomasmulvaney]

I agree that the outer is probably not necessary. I like the choice of an IWalk protocol so walking can be extended in the future.

[mpenet]

Do you need me to modify anything on this? (I need it for a toy project, but worst case I can use a local fork).

[thomasmulvaney]

A quick squash would be nice, but otherwise this looks great. Thanks!

[mpenet]

There you go! Squashed.

[heyLu]

Thanks!