Thanks again for sharing!
Since you've been so kind as to share your know-how so far--is it idiomatic to keep the tests in the same source file as the code or are you simply putting them all in the same file just for purposes of illustration?
And that tip about #:type-name is very welcome as well. Some of the names I come up with are pretty clumsy; I don't think #:type-name will help with that but it's a step in the right direction.