meta/hhvm ? reverse-engineered prompt

Build me an open source virtual machine for running Hack programs, with a fast just in time execution path and support for both command line scripts and web requests.

I want to be able to run a Hack file directly, like hhvm example.hack, and also use it behind a web server so I can serve a simple site from main.hack. If it makes sense, include easy local setup, clear getting started steps, and a straightforward way to run it with either the built in Proxygen option or a FastCGI setup.

Please make it feel like a real developer tool, with good error messages, useful docs, and a clean build from source. If there are any current best practices or updated setup details you need, look them up online first.