Kotlin has lots of nice features for this kind of stuff. Including extension functions and it comes with lots of those for existing Java APIs. And a nice thing

Kotlin has lots of nice features for this kind of stuff. Including extension functions and it comes with lots of those for existing Java APIs. And a nice thing with extension functions is that they also work against interfaces, generic types, etc. So, there is no need for a Stream.of in Kotlin. You just call .filter, .map, etc. on anything that you'd want to call that on that is a List, Map, Array, Flow, Sequence, whatever. Java Streams too probably but I haven't had a need for using those in five years. As for doing things in parallel, that's where Kotlin co-routines shine.