> Hack is quite different in various non-trivial ways [citation needed]. In what non-trivial ways is Hack different to PHP? Of the three distinguishing featur

> Hack is quite different in various non-trivial ways [citation needed]. In what non-trivial ways is Hack different to PHP? Of the three distinguishing features highlighted on https://hacklang.org/ https://hacklang.org/, PHP has two (the exception is generics, which I don't think PHP has added... yet).