In order to learn the nom crate (and higher order parsers in general), I've made a simple json parser.
Big thanks to ericseppanen for his writeup on his own parser toy:
https://github.com/ericseppanen/json-parser-toy
1Password had a decent video explaining it:
https://www.youtube.com/watch?v=zHF6j1LvngA
https://www.youtube.com/watch?v=9GLFJcSO08Y
And nom has a parser "cheat sheet" in their repo:
https://github.com/Geal/nom/blob/main/doc/choosing_a_combinator.md