You have to export the code to make it callable, and I had to write some adapters on the Kotlin end. But very doable for integrating if you need to.
This code is quite specific, but you get the idea. Export symbols:
https://gitlab.com/crossref/rest_api/-/blob/main/src/cayenne...
Convert Clojure structures to Kotlin classes:
https://gitlab.com/crossref/manifold/-/blob/main/src/main/ko...