Ypsilon is an implementation of Scheme programming language for real-time
applications, which conforms to the latest standard R^6RS.
Ypsilon features mostly concurrent garbage collector optimized for systems
with multiple CPUs, and an easy to use FFI.

WWW: http://www.littlewingpinball.net/mediawiki/index.php/Ypsilon
WWW: https://github.com/fujita-y/ypsilon