Very cool project :)

I wondered if you'd considered whether it would be possible to reuse the open source upstream Buck2 prelude as well? It seems that Nix is a great source for toolchain definitions, but reimplementing things like Rust/Haskell/OCaml/C++ etc on top separately from the upstream prelude would be a lot of work.

Happy to chat further over video conference or similar if that's easier, and happy to answer any questions you have about Buck2. It's still early days, but integration with Nix is super cool.