It's brilliant: all useMemo and useCallback can be removed and you get the same runtime performance and then some, at the cost of only a slight increase in code size.

A small downside at the moment is the build time. This change will hopefully help address that because it will no longer depend on babel.

> Note that the conversion from any AST into our HIR is complex, and we can only maintain one version. Hence we've aligned on using a Babel-like AST as our public API. Another key point is that we don't yet implement our own scope analysis (since the TS version of the compiler relied on Babel's scope analysis), so for now we require that the scope data be serialized. It's a denormalized graph, and some metadata has to be stored to associate nodes with scopes. We're open to feedback about the AST and scope representation - we iterated a bit just to get things to work, but it can be more optimal.

Whats funny is I had been using Rust more with Claude because of this, and before Anthropic did their rewrite of Bun I tried a Rust rewrite of a C# project I had laying around (.NET 3.5 from back in 2008) it wasnt perfect but its nearly there now, mostly for fun, and I did it because for a little while I realized LLMs can be useful for more serious refactors, and figured it might be good for a language rewrite. Sure enough.

I think rewriting tooling that takes text and transforms it in a language like Rust is fine for JS projects, so is Go, which is why TypeScript is migrating to Go. The “free” optimized speed increases are worth it, at the temporary cost of dealing with the migration for a year or two, which with LLMs trims down the initial work into a week effort it seems? Wild.