Clojure has a fully optional, very grokkable and well-defined map from Clojure to Java, in the form of protocols and gen-class. Protocols are a natural part of

Clojure has a fully optional, very grokkable and well-defined map from Clojure to Java, in the form of protocols and gen-class. Protocols are a natural part of the language, and if you need a concrete gen-class, because Clojure is functional it's easy to plug whatever Clojure functionality into a Java interface.