BTW, for anyone interested in graphics programming, I highly recommend
checking out the Agave OpenGL demos:
<https://github.com/dharmatech/agave>. They run in Chez, Ikarus and
Ypsilon and are quite easy to install from Akku
(https://akkuscm.org/packages/agave/).

These are under the Apache License and probably are possibly under 500
LOC even including library code (if the Scheme OpenGL wrapper doesn't
count). Maybe we could incorporate these, or something in this spirit,
into the example programs.

While we're on the topic of graphics, one of the most delightful CS
papers ever is FunctionalGeometry (Henderson 2002):
<https://eprints.soton.ac.uk/257577/1/funcgeo2.pdf>. He defines a
functional graphics language and replicates an Escher drawing with it.
The book How To Design Programs also uses this language and it's
available for Racket:
<https://docs.racket-lang.org/teachpack/2htdpimage.html>.