Facebook's Hack and HHVM

Is the HHVM still in use at Facebook? Or did PHP catch up?

Facebook uses Hack. Hack is to PHP what C++ is to C, sort of. You can take PHP code and run it as Hack code, sometimes, but there are lots of reasons why PHP code might not be valid Hack code these days (Hack has diverged from upstream).https://en.wikipedia.org/wiki/Hack_(programming_language)

Wasn't there a PHP compiler at Facebook called Hip-hop?

Well, Facebook spun PHP off into Hack if that counts.

PHP is amazing! Facebook uses Hack on HHVM.

Don't forget that Facebook used PHP: https://en.wikipedia.org/wiki/HHVM

Facebook doesn't run on plain old PHP, it's compiled with HPHP into "highly optimized" C++

Is there any official reference to backup the claim? I doubt Facebook would spend effort on doing this since they have already port PHP to C++ with Hiphop.

Facebook's HHVM (HipHop VM) compiles webpages into native machine code that can be executed directly on the processor. People often confuse HHVM with HPHPc, also made by Facebook. HPHPc came first; it was a converter that converted all the PHP files in a folder into individual C++ files. In other words, you would end up uploading the C++ files to the server, not PHP files. Facebook abandoned HPHPc early on for multiple reasons (it was actually developed by a single developer as a tool for o

I think they meant Facebook switched their PHP code to Hack and HHVM, their own PHP-like language and implementation.