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:See the release announcement for details on the other dishes.