hoping to have @Andrew (cl-fast-ecs library), @oofoe and @Jummit comment here as well. You can read about their approach to ECS in their devlogs https://awkravchuk.itch.io/cl-fast-ecs/devlog/622054/gamedev-in-lisp-part-1-ecs-and-metalinguistic-abstraction. https://oofoe.itch.io/rfk2k/devlog/624237/handling-entities and https://jummit.itch.io/tic80-access-battlers/devlog/622949/pre-jam-preparations