A partial (or finite) map is defined very much like a list in Coq. The [find] and [update] operations are easy to code with the help of the [option] type. A theorem is proved; it shows that the two operations work together.
Textbook: https://clarksmr.github.io/sf-lectures/textbook/lf/toc.html
Supporting materials: https://github.com/clarksmr/sf-lectures/tree/main/notes/lf
