Re:PHP 7 Released
by Killswitch on Wednesday December 02, 2015 @09:47AM
(#10663196)
Hack is derived from PHP, they've only tuned the engine for their own usecase, and not to mention anyone in the PHP community can use Hack.
Hack is basically the TypeScript of PHP. Regular PHP works fine on Hack, but you can start incorporating Hack things into your PHP.
If you want to go that route, then my site is actually powered by Babel and not JavaScript.
http://hacklang.org/
As far as I understand, most/all new development is done in Hack.
Granted, a lot of Hack features are starting to make their way into PHP (much like how exciting new TypeScript features are making their way into ES6 and above), but focus has been shifted to Hack.