>the superb racket/class encapsulation mechanism.

Superb? The racket class system strikes me as awful/embarrassing. The language at least looks functional in nature, but to do OO they implemented this ridiculous single dispatch mechanism (manually calling "send" no less!). Why on earth didn't Racket end up with a CLOS like system? They could have made anything they wanted, and yet they ended up with a system that will require people to write the Visitor pattern. Shocking.