Buck2: Our open source build system

I was reading on & on, going, yeah sounds great, but when are you going to mention that it runs on Mercurial, which just puts such massive distance between FB & the rest of the planet?

They do mention that it supports virtual file systems through Sapling, which now encompasses their long known EdenFS. I'd like to know more but right off the bat Sapling says it is:

> Sapling SCM is a cross-platform, highly scalable, Git-compatible source control system.

Git compatible eh? Thats a lot less foreboding. (It is however a total abstraction over git with it's own distinct cli tools.)

I hope there are some good up to date resources on Sapling/EdenFS. I have heard some really interesting things about code kind of auto getting shipped up to the mothership & built/linted proactively, it just at commit points, which always sounded neat, and there seem to be some neat transparent thin checkout capabilities here.

https://github.com/facebook/sapling

I'm not sure how Mercurial is relevant. From reading the Buck2 getting started docs, it looks like it works just fine with Git repos.

It indeed is not the primary concern of build systems. For many folks, there's some ci/CD systems checking stuff out & feeding their build tools.

Buck2 notably though tries to be a good persistent incremental build system, and it needs much more awareness of things changing. It does integrate with Sapling for these kind of reasons.

So the boundaries are a bit blurrier than they used to be between scm/build/ci/CD tools.

My understanding is that Buck2 uses Watchman (disclaimer: I'm one of the maintainers) so it can work with both Git and Mercurial repositories efficiently, without compromising performance.