Comment by gf000

Mill does work with idea (via the build server protocol), and the ideas behind it are very sound (a build tool is basically a function calling other functions - on which they depend. You just want to parallelize their running and cache their results.

But it does have a learning curve and you may sometimes end up having strange error messages. (As an implementation, it's basically Scala macros turning normal looking scala functions into a static task graph). It is getting better and better support for mainstream java build setups, and it's possibly the best tool for something very custom. In between the two extremes, you may or may not have a better time with Gradle/Maven.