R5RS has a clean, small core designed with functional programming in mind. This is both: a boon and a curse. One must add all sorts of libraries to build a dece

R5RS has a clean, small core designed with functional programming in mind. This is both: a boon and a curse. One must add all sorts of libraries to build a decent application. At the same time, it is better than Lua, if you're thinking of adding extensibility to your product. While using it as an extension language for a desktop product, I was irked by only one facet: threads. It really took quite a lot of gyrations to get the multithreaded implementation right. In all fairness, that is more of an implementation challenge, but still, one that must be overcome.