Scheme-xp is the X protocol implemented in Scheme. It is not a binding, where scheme functions wrap around C code, but a complete reimplementation.
Currently, it's more of a proof of concept than a fully functioning replacement for xlib, and it will remain so for a while longer. Although I still want to come back to this code, life is rather complicated right now and it will be a while.
Eric Marsden sent me a patch catching scheme-xp up to the latest scsh version, but I'm not in a position to test and integrate it.
The current version of scheme-xp remains scheme-xp-0.01.tar.gz. You may also browse the code online.
Thanks for your interest.