You can't just pass in a Clojure `fn` into a Java lambda function. You have to `reify` the interface and implement the single method. It's annoying and verbose and frustratingly the equivalent code is considerably cleaner in Java as a result.

I know that this is a product of how Java implemented lambdas by having interfaces with a single method, and I'm not saying that it would be trivial to add into Clojure, but I don't think it's impossible and I think people have been complaining about this for more than a decade now.

So while I love Clojure, it's probably my favorite language, I do get a little annoyed when people act like it's "stable" because there's nothing to fix.