I like it! Really nice API.

I had an idea about writing something similar, but for multimethods, but never got around thinking it through and trying it out.

The way defmulti and defmethod work is that they do a concurrency safe operation on a data structure, which is used to dispatch to the right method when you call the function.

My hunch is that it should be possible to do something similar by using core match. What I don't know is whether it's a good idea or a terrible one though. When you're already doing pattern matching, then you likely want to see everything in one place like with your library.