Take a look at The Guardian newspaper's github repository for some professional Scala. It ain't pretty - implicits all over the place, liberally mixed with Cats and Scalaz. This is Scala's big problem - taken in isolation Scala-isms are comprehensible but it's the way the cleverness composes that leads to a big ball of mud. Add to that the tendency of Scala connoisseurs to throw-in Cats and Scalaz at every turn and you have a recipe for disaster.