Conclusion

Functional effects are blueprints for concurrent workflows, immutable values that offer a variety of operators for transforming and combining effects to solve more complex problems.

The ZIO type parameters allow us to model effects that require context from an environment before they can be executed; they allow us to model failure modes (or a lack of failure modes); and they allow us to describe the final successful result that will be computed by an effect.

ZIO offers a variety of ways to create functional effects from synchronous code, asynchronous code, pure computations, and impure computations. In addition, ZIO effects can be created from other data types built into the Scala standard library.

ZIO uses the environment type parameter to make it easy to write testable code that interacts with interfaces, without the need to manually propagate those interfaces throughout the entire application. ZIO also ships with default services for interacting with the console, the system, random number generation.

With these tools, you should be able to write your own simple ZIO programs, convert existing code you have written into ZIO using effect constructors, and leverage the functionality built into ZIO.