Comment by eastoeast

I've actually just recently been through this myself. I'm also building something for kids to build games in. But much more opinionated than Easel. It's interesting to me that Easel looks declarative but is imperative.

I've actually gone with a 100% declarative approach. Basically you define effects, which are executed in response to certain interactions. There's a comprehensive targeting system. But the best part is this is all type-safe using TypeScript, the declarative structure is enforced. That means even when you chain effects, nested effects are able to access (incl. autocomplete) the targets of parent effects etc. Whilst this provides a super nice experience to consume, it's definitely non-trivial to build this system.

https://breaka.club/blog/why-were-building-clubs-for-kids

Oh yes, handling interactions and dependencies and what is affected by what. I did a lot of React development (as in the frontend web framework) before making Easel and was quite inspired by how it hooks to change. The way you give it a little routine, it says what it depends on, and then it just fully re-executes that whole routine when the dependencies change. So in Easel when you say `with Health { ... }` it makes a behaviour that re-executes every time the Health changes. But, if it just reran the behaviour, then you'd end up with it adding a new sprite (for example) every time it re-executes, until you've got hundreds of them. So the other trick is the Easel compiler assigns an implicit ID to things like sprites so that it will replace rather than add the second time around. It's built into the programming language so you don't see it (most of the time). It actually took me 2 years to come up with that, which is both cool and depressing when I can explain it in one paragraph.