Thanks for the tip. Also, we are working on making it easier to isolate opam packages and npm packages side by side in one development environment so that problems like this are avoided. This allows you to build a project that depends on opam packages for build time tooling inside your JS projects. That project is called esy, and it’s a young addition to the ecosystem but something I’ve been using to greatly increase my own productivity for a while now. It will not make BuckleScript compile opam packages (that is not BuckleScript’s goal) but it will at least make the two ecosystems coexist simultaneously.