I work at Facebook as well, but mainly in JavaScript so I haven't done a lot of PHP either :) You could use a common PHP framework like FuelPHP, Laravel or Koh

I work at Facebook as well, but mainly in JavaScript so I haven't done a lot of PHP either :) You could use a common PHP framework like FuelPHP, Laravel or Kohana. I'm not sure which frameworks are 100% compatible with HHVM, but I think they're all getting quite close to 100% (or may even be at 100% with the 3.0 release). It's fine to mix PHP and Hack in the one project, so you could use a PHP framework and use Hack just for your code.