Chicken, together with its eggs system has always struck me as very professional feeling. Plus, bind (dead simple ffi for C stuff) seems like a huge win where C is required.

That all said, I've become quite enamored of Clojure's various data types. Does anyone know if there has been an attempt to create things like immutable maps, vectors, and whatnot for scheme (esp Chicken Scheme)? I found a blog post a while back that talks about FSet for common lisp, but have failed to find an analogue for scheme. http://blog.thezerobit.com/2012/07/21/immutable-persistent-d...