Scala was the only time in the past decade I actually enjoyed programming, but it wasn’t a great idea to use for our relative large team as the amount of expression allowed comes at the expense of subjecting others to your mental model of how things should be done and having them spend undue time grokking it. I view this largely as a deficiency in style guidance, but Scala attracts very opinionated people in my experience and I say good luck to any style guide being upheld across a large org or team.

Kotlin has been nothing but great for me though. (Different company). It’s largely the best parts of Scala for me and without the headaches that come from some allowed patterns.