Typed Lisp with Pattern Matching
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))