This is awesome and something I've felt could be a (another) killer app for Rust.

If Rust interfaced well with a convenient scripting language that runs fast and safely, the language would morph into a platform where you could quickly prototype in the high level language and then convert well-defined structures to hardened Rust.

It'd be fantastic for games (no wonder the Piston folks are exploring this), web backends, and native apps.

If this reaches the ease of use of Python, I'll never look back.