[toast0]

As someone who has wrote PHP as part of a job in the 90s, the 00s, and the 10s, and at least seen some Hack at Facebook (I think I wrote a tiny amount of code in Hack, but it wasn't in the main repo), Hack code, especially the idiomatic code in the main repo, is pretty detached from PHP.

Yes, there's $'s everywhere. Otherwise, it looks more like a Java codebase than a PHP code base, IMHO. Although, maybe I've mostly seen PHP code bases where there's less abstraction/OO::Explosion, I've never worked long term on PHP code with an opensource framework, and I didn't like what I saw when I had to look at things in those frameworks. IMHO, that makes for too much hidden logic, and makes it hard to understand what's happening, and why it takes 20-50ms to output a hello world.