Most #BuildTool plugins should be developed as an library or CLI app first. Then, you can feed everything from your build tool into it. This makes reusing it in other build tools much easier. Also testing is easier that way. 

When looking at the current tooling landscape in #Scala or #Java, most tools are exclusive to  one build tool. They use the API of that tools and can therefore not easily reused by others. 

 @4d9fc3ff With some work we could define a single build-system->IDE API that works for everything - cmake, rust, ada, java, and so on.