Conversations About The Internet #5: Anonymous Facebook Employee : This is a wide-ranging interview with an anonymous Facebook employee, which is very interesting in itself, but particularly for this bit about their infrastructure.
Our site is coded, I’d say, 90% in PHP. All the front end — everything you see — is generated via a language called PHP. He is creating HPHP, Hyper-PHP, which means he’s literally rewriting the entire language. […] So this engineer is converting the site from one that runs on a scripted language to one that runs on a compiled language.
I couldn’t find any reference to Hyper-PHP anywhere, so I’m assuming it’s a Facebook-only thing. Some pre-compiled derivation of PHP.