Part 2. Becoming functional

In this part we’ll build on the foundations laid so far, and you’ll see how some techniques introduced in part 1 for limited scenarios can be generalized, enabling you to write entire applications in a functional style.

Chapter 6 discusses the functional take on validation and error handling.

Chapter 7 shows how you can modularize and compose an application with functions only, using techniques like partial application and the powerful Aggregate function (fold).

Another core function, Apply, is discussed in chapter 8, which also teaches you about implementing the LINQ query pattern and compares some functional patterns like applicatives and monads. Chapter 8 also introduces a technique called property-based testing, which verifies that your code observes certain properties by throwing random data at it.

Chapter 9 discusses the functional approach to representing state, identity, and change through immutable data objects and 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 10.

By the end of part 2, you’ll have acquired a set of tools enabling you to effectively tackle many programming tasks using an end-to-end functional approach.