Interesting article. While reading it I wrote a version of the code in Racket. YMMV but I think it turns out cleaner, especially towards the end. https://gist.

Interesting article. While reading it I wrote a version of the code in Racket. YMMV but I think it turns out cleaner, especially towards the end. https://gist.github.com/bon/801fdb6dbced0efdb83a358bb4f6285f https://gist.github.com/bon/801fdb6dbced0efdb83a358bb4f6285f