Sorry, I know this isn't specifically about Stanza, but I know Patrick, you're a lisp hacker.

Do you know about Shen? http://shenlanguage.org/

It's pretty interesting how it's a Lisp, but also how it makes heavy use of ML-like pattern matching.  For example:

(define foldl
    F Z [] -> Z
    F Z [X | Xs] -> (foldl F (F Z X) Xs))