Two years ago Guile Scheme, the official extension language of the GNU project, released version 2.0, a major upgrade to the implementation. As part of the two year anniversary, the maintainers organized a challenge to hack a small project using Guile in 30 days as part of a birthday software potluck. The two coolest dishes appear to be OpenGL support using the FFI, and XCB bindings built using the XML specification for XCB: "guile-xcb is a language implemented in the Guile VM that parses the XML files used by the xcb project to specify the X protocol and compiles them into Guile modules containing all the methods and data needed to send requests to the X server and receive replies/events back. If new X extensions are added to the xcb library, guile-xcb can compile and add them with no additional work. " See the release announcement for details on the other dishes.