you might be interested that I developed a whole coding paradigm (Declarative Domain Paradigm, DDP) around nested and annotated enums.

it is fully declarative, immutable and easy to understand as the code reads like normal English — with funky interpunctation:

execute(.lighting(.turn (light,.on)))

store.change(.by(.adding (.favorite(fav))))

Khipu implements uncle bob's clean architecture in DDP: https://blog.devgenius.io/khipu-rapid-and-sustainable-software-creation-in-swift-using-engineering-and-science-principles-312a933cce57?sk=8359f48cc06571e53de156db8cbc005c