> Can I even use e.g. a Scala collection from Java? (let alone Clojure, Kotlin, etc) Yup to all. Sometimes the code comes out looking a bit ugly (e.g, you can

> Can I even use e.g. a Scala collection from Java? (let alone Clojure, Kotlin, etc) Yup to all. Sometimes the code comes out looking a bit ugly (e.g, you can access default parameters from Java, but it's done by calling methods with kind of awful auto-generated names), but the only things you really can't get at are things that relies on implicits, type tags, or traits with fields.