Part 3. Functional designs

In this part, we’ll widen our focus to designing entire applications or tackling cross-cutting concerns with a functional approach.

Chapter 8 discusses the functional take on validation and error handling.

Chapter 9 shows how you can modularize and compose an application with functions only, using techniques like partial application and the powerful Aggregate function (fold).

Chapter 10 discusses another core function, Apply. It also teaches you about implementing the LINQ query pattern and compares some functional patterns like applicatives and monads. Chapter 10 also introduces a technique called property-based testing, which verifies that your code observes certain properties by throwing random data at it.

Chapter 11 discusses the functional approach to representing state, identity, and change through immutable data objects, while chapter 12 discusses immutable data structures. These principles can be applied not only to in-memory data but also at the database level, and this is shown in chapter 13.

By the end of part 3, you’ll have acquired a set of tools enabling you to effectively tackle many common scenarios using an end-to-end functional approach.