We went to the Scala Days 2018 in Berlin. The talks we liked the most were:
The Keynote of Adriaan Moors and Martin Odersky. They spoke mostly about Scala 3.0. Some interesting aspects were:
The Talk «Functional Interpreters and You» is about Free Monad and Finally Tagless. That's a pattern from Functional Programming which helps building DSLs. The advantage of it is that these DSLs can easily be composed and interpreted on different Interpreters.
The last Talk «Type Parameter Power-Up!» shows all the Type Parameters of Scala. (Covariance, Contravariance, Invariance, Upper Bounds, Lower Bounds, View Bounds and Context Bounds.) It also explains how and when they are used.