> Parent/child and handler/emitter relations are very common. You can work around it, but unnaturally.

I think this is where we disagree.

If your UI data flow is not unidirectional, that's a problem you brought yourself into, Rust or not.

For reference: I don't do my UIs in Rust, but the language is not the reason why, and I still use unidirectional data flow even on GC'd languages.

> Because the 'best' language for JSON is obviously Javascript/Typescript

As a TypeScript fan (it's my main language)... ser/de sucks in TS and IO boundaries are most of my pain points with it. My top 2 things that I miss from Rust are: (1) serde/rkyv (2) affine types. Zod has been great but it's still miles behind a proper ser/de library.

And yet I still can't see how JSON is relevant for UIs.