Saphire 
Ruby inspired type system for JavaScript.
Supported Platforms
Currently this is only supported on NodeJS and compatible V8 implementations. It requires Harmony proxies in order to run correctly.
Acknowledgments
Most of this code was based on MRI/YARV and Rubinius.
We'd like to say a big thank you for all contributors of those projects which without them we won't be able to create this project.