I just got so fed up with Starlark trying to do a nontrivial RBE prelude that's fairly different than Meta's.

I added WASM/WASI bindings and wrote the prelude in Haskell.

Both the bindings and the prelude took less time than I already wasted on multiple attempts in Starlark that all collapsed into string goop.

It's nice to be able to bound the execution environment in a build tool but still use a serious programming language.

Given Zig has excellent support for targeting WASM, seems you'd get the same advantages.