Hack
Gradually typed PHP dialect from Meta — adds static typing, generics, and modern language features to PHP.
gradual
jit
since 2014
oopfunctionalimperative
Hack was developed at Facebook to bring static typing to a PHP codebase with hundreds of millions of lines. It runs on HHVM and adds generics, nullable types, lambdas, and async/await to PHP’s model. The gradual type system allows incremental migration of existing PHP code.