tl;dr: I implemented an experimental Mill plugin that publishes a Scala library as a pure Java library.
This experimental plugin grew out of my efforts to learn the Mill build tool. I decided to tackle a use case I found challenging:
In the past, before Scala 3 introduced the TASTy format, getting different Scala versions to work together wasn't always easy or possible. In addition, while calling Java functions from Scala has always been intuitive, the reverse (calling Scala from Java) has not always been straightforward. Personally, I think a pure Java library is still the way to go if you want to reach both Java and Scala developers. I asked myself: is it possible to build a pure Java library of a decent size while still using my favorite programming language, Scala? My idea was to create a Java facade for a Scala library, bundle all necessary Scala dependencies within the Java JAR, shrink the output, and shade the third-party Scala classes to avoid name clashes. It sounds like a bold experiment, but I gave it a try and implemented a Mill plugin to support this specific use case. For me, this was a case study to see how customizable the Mill build tool is.
A "hello-world" example project you find here:
