[ckwalsh]

> I am also wondering if Meta still uses PHP or Hack

Meta’s WWW codebase is its oldest, and still written in Hacklang. Lots of internal tooling is also written in Hack.

I wouldn’t be surprised if there are more committed lines of Hacklang than any other language (although, a good chunk of that is codegen, vs other core languages where codegen is part of the build process).

[ameliaquining]

Why don't they do codegen at build time in Hack?

[paxys]

Hack does JIT compilation.

Even otherwise, at the scale the company operates it's much better to run codegen once at commit time rather than recreate the entire codebase on every deploy (several times a day) which would take forever.