Scalaz 8 is the latest edition of the popular functional programming library for Scala. In this whirlwind tour, maintainer John A. De Goes discusses some of the hottest features of Scalaz 8, including all of the following: * A fast, concurrent, and leak-free effect system, which has small, composable, and powerful primitives for building practical, real-world software; * A non-linear type class hierarchy, which permits a more powerful hierarchy that infers well without devastating ambiguous implicit errors; * A new encoding for abstractions in category theory that providers higher fidelity and enables new categories of useful software to be developed; * A Scala 2.12 encoding of opaque types that powers improved performance and better developer UX. In this tour, you’ll see how the design of Scalaz 8 was inspired by a desire to provide Scala developers with a principled, performant, and pragmatic library that never sacrifices the safety and equational reasoning properties of functional programming. You’ll see live code snippets that show you how solving complex real world problems is simpler, faster, safer, and more reasonable than in previous versions of Scalaz. And hopefully you’ll be inspired at just how far functional programming in Scala has come in the past decade.