Chapter 3: Functional Data Structures

In this chapter, we'll learn the concept of functional data structures and how to work with them. We'll use this as an opportunity to introduce how data types are defined in functional programming, learn about the related technique of pattern matching, and get practice writing and generalizing pure functions.

Chapter 4: Functional Error Handling

In this chapter, we'll learn the basic principles for raising and handling errors functionally. The big idea is that we can represent failures and exceptions with ordinary values, and we can write higher-order functions that abstract out common patterns of error handling and recovery.