Hi again,
first of all, apologies to Dan Liebgold for butchering his last name in my previous email.
Dan just wrote me and clarified an interesting point. In his words: "We didn't use our own implementation of Scheme, we used PLT Scheme and layered a language on top of it (including a set of SRFIs)".
I think that it's very neat that they didn't have to write their own implementation. Hopefully, we might get more technical details soon.
Guillaume