Recursion schemes are a topic too few people know about in my opinion. I wrote two simple and interactive introductions. One in Javascript [1] and one in Elixir as Livebook [2]. The Elixir version contains a few more practical examples.

[1]: https://static.laszlokorte.de/recursion-schemes/ [2]: https://github.com/laszlokorte/elixir-recursion-livebook/blo...

Interesting syntax: https://effekt-lang.org/docs/casestudies/ad

> do add(do mul(do num(0.5), do exp(do add(do num(1.0), do mul(do num(2.0), x)))), do exp(do mul(x, x)))