A virtual machine for executing programs written in Hack.

The Hack Standard Library

The sources for how we have built the HHVM packages.

A Hack library for writing unit tests expressively

Class libraries for XHP. XHP is a Hack feature that augments the syntax of the language such that XML document fragments become valid Hack expressions.

Autoload classes, functions, enums, constants, and typedefs on HHVM

Syntax highlighting and typechecker integration for Hack.

The official Hack Language specification.

Escape Velocity Nova Fix for Modern OS X

Provides classes to use with XHP for common components of Twitter's Bootstrap library.

The Hack and HHVM manual and documentation

A complete app.net library written in JavaScript. Exported as a jQuery plugin.