Since 1994, the original Gang of Four Design Patterns book, "Design Patterns: Elements of Reusable Object-Oriented Software" has helped developers recognize common patterns in development. The book was originally written in C++, but there have been books that translate the original design patterns into their preferred language. One feature of "The Gang of Four Design Patterns" that has particularly stuck with me has been testability for the most part. With the exception of singleton, all patterns are unit testable. Design Patterns are also our common developer language. When a developer says "Let's use the Decorator Pattern" we know what is meant.

What's new though is functional programming, so we will also discuss how these patterns change in our new modern functional programming world. For example, functional currying in place of the builder pattern, using an enum for a singleton and reconstructing the state pattern using sealed interfaces. We will cover so much more, and I think you will be really excited about this topic and putting it into practice on your own codebase.