Well, there's kinda an example in the docs [0]. Kinda related: this appears to be built on the Clack webserver and its homepage lists code snippets of Lucerne alternatives that are built on top of Clack as well [1].
I read through the Twitter-clone example in the docs after I posted my comment. The Twitter-clone is a little bit longer than a quick snippet. I just wanted something that showed a route pointing to an index function returning a hello world and a line of code starting the server.
Also, it is definitely Flask inspired. I might have to do a more in depth comparison of the two.
[0] http://eudoxia.me/lucerne/docs/example--a-twitter-clone.html
[1] http://clacklisp.org/