Proof of concept: s/defmulti + arguments-checker

[frenchy64]

arguments-checker implements idea outlined in #450.

Multimethod wrapping for non-graalVM JVM Clojure only atm.

[w01fe]

Interesting, thanks for exploring this direction. I know this is just a draft for now, not sure if you are looking for feedback on the whole thing, or just the arguments-checker piece, or just putting it up for CI?

In the future I would ideally suggest making a proposal before putting up an implementation for a new feature like s/defmulti, but that's of course up to you. For historical context, we had deliberately omitted this one because it wasn't clear there was significant value above and beyond what's provided by s/defmethod, especially given the necessary complexity to implement it.

In any case, I'm open to reconsidering that but to be able to usefully comment on something like this I would really appreciate at some point an explanation of what user need you're trying to address, how you went about solving it and new user-facing syntax, explanation behind tricky implementation details (why did you need to drop to java, how safe is this from a maintenance perspective), etc. Thanks!

[frenchy64]

Someone in #malli in clojurians wanted similar functionality for malli and I thought I'd try it in Schema since I'm more comfortable here. I will move this to my repo since this is just exploratory.