Clojure's Java interop is smoother than Scala's, but not as seamless as Kotlin's. Kotlin is modern syntax for the same Java APIs and programming philosophy. Scala and Clojure are radically different languages (from Java as well as each other), for better or worse.

Kotlin is a modern Java-replacement, while Clojure and Scala have different strengths and weaknesses. That's not to say that you can't write many applications in any of the four languages, but the "feel" of the codebase would be completely different in Clojure or in Scala, while Kotlin would feel the same (but would be leaner).

Clojure devs don't seem to care about performance.

Just check how the JVM gets the blame for what is essentially Clojure initialization time.

There are some in the community trying to improve the situation, but those are kind of forks like Skummet.

> Clojure devs don't seem to care about performance.

Ridiculous. Clojure devs care a lot about performance. We just care more about correctness.

By "performance" I think you specifically mean "startup time."

I think there is a big difference between startup time and runtime performance. It is well-known and fully acknowledged by the Clojure community that starting up a Clojure environment and REPL takes a while. But are you also suggesting there is a problem with Clojure runtime performance?

I got that understanding given how performance improvements get postponed version after version. Apparently they will be coming on 1.8.

After the start time, In my testing, I have never seen Java code that's faster than it's commensurate Clojure code. I've seen the reverse.