Are you talking about Facebook? They&#x27;re transitioning over to Hack.<p><a href="http:&#x2F;&#x2F;hacklang.org&#x2F;" rel="nofollow">http:&#x2F;&#x2F;hacklang.org&#x2F;</a><p>As far as I understand, most&#x2F;all new development is done in Hack.<p>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.