Allan MacGregor has a new post to his site introducing you to Hack, the recently released language from Facebook based on their work with the HipHop virtual machine.

Recently Facebook unveiled Hack, a new programming language that aims to provide developers with the tools to write and ship code quickly while catching errors on the fly. Hack is as programming language designed to work with HHVM and the same time it works seamlessly with PHP as Facebook lead devs. [...] So does that mean that Hack is just a faster more efficient PHP implementation, right? Wrong, Hack is much more than that, the language brings features that are normally found in statically typed languages to the dynamically typed world of PHP.

He focuses in on the static typing functionality of Hack a bit more and includes an example of PHP code where Hack would catch the type shifting. He also briefly mentions some of the other features including built-in collections, traits, generics and asynchronous programming.