This is Hack, not PHP. I considered Hack and HHVM a few years back, but with PHP 7, they really have little to nothing to offer PHP development and last time I

This is Hack, not PHP. I considered Hack and HHVM a few years back, but with PHP 7, they really have little to nothing to offer PHP development and last time I checked, there were still serious incompatibilities. The speed gains for both HHVM and PHP 7 are very similar over PHP 5. I really cannot see using Hack or HHVM, or even considering them, unless they get another 2x or more speed improvement over PHP 7. In my testing, they're head to head and that in no way justifies the migration. Hack is NOT PHP, sorry.