For what it's worth, Clojure also has a much closer fit to Elixir Protocols called... a Protocol.
https://www.braveclojure.com/multimethods-records-protocols/...
They too can only dispatch on the type of the first argument, but are more structured (you can add multiple pieces of behavior at a time) and performant than multimethods where that's the behavior you're looking for.
https://github.com/clojure/core.match -- pattern matching as a library
https://github.com/killme2008/defun -- using core.match to implement Elixir/Erlang-like function definition
https://github.com/noprompt/meander -- advanced pattern matching, for some fun and flavor :)
What's also fun is that core.match is implemented using a paper from INRIA on how to efficiently convert patterns into decision trees:
https://github.com/clojure/core.match/wiki/Understanding-the...
Here's Jose Valim talking about it:
> I’ve learned a lot also from Clojure because, at the time I was thinking about Elixir, Clojure was already around. I like to say it’s one of the top three influences in Elixir
[...]
> The main, the top three influences are Erlang, Ruby, and Clojure.
[...]
> I was like, no, but I’m going to call them protocols because there are a lot of similarities between Clojure and Elixir in terms of them being dynamic languages and in terms of the macro system. I was like, okay, I’m going to call them protocols because the closest thing we have today to what I want is Clojure
And he goes on talking about more inspiration and similarities from Clojure like Agents, etc.
Full exert is here: http://blog.cognitect.com/cognicast/120