This talk may be from almost a year ago now but it is a really great talk, from John De Goes, about 'Thinking Functionally'. Given at the ScalaUA conference he runs through effects; giving a backstory and code examples.
In Thinking Functionally, you'll learn how a functional programmer thinks about problems as John live-refactors a concurrent imperative program to its purely functional equivalent — which is shorter, more powerful, more type-safe, and far easier to reason about and test. Don't miss this chance to witness both the "why" and the "how" of functional programming and learn more about ZIO, the hot new Scala library for asynchronous and concurrent programming that makes it easy to conquer the impossible.
This talk was given by John De Goes at ScalaUA.