A year ago at ScalaIO, John A. De Goes revealed the design of the Scalaz 8 IO monad in an epic standoff between Cats Effect and Scalaz 8 IO that became known as the #ClashOfIOs. Now, one year later, the ecosystem has been forever altered, as the event inspired other projects to adopt some of the Scalaz 8 design decisions.

Since that date, the Scalaz 8 effect system has continued rapidly evolving. The system has been pulled out into ZIO, a standalone library with no dependencies. A new bifunctor design allows typed error handling; performance has been improved further; the error model refined to precision; the code battlehardened; and new primitives have been introduced for composable, typesafe, leakfree, and highperformance concurrency.

In this presentation created exclusively for ScalaIO, John A. De Goes presents the latest work on finalizing the effect system. John takes attendees on a tour that reveals the beauty and the practicality of ZIO, and challenges attendees to embrace a functional way of solving the hard problems they encounter at work—without compromising performance or principles.