I suddenly remember FbExperiment on building Mercurial server using Rust https://github.com/facebookexperimental/mononoke https://github.com/facebookexperimenta

I suddenly remember FbExperiment on building Mercurial server using Rust https://github.com/facebookexperimental/mononoke https://github.com/facebookexperimental/mononoke And yes.. it's for extension modules (maybe just the beginning)