Part 3. Advanced techniques

This part tackles the complex topics of state management, asynchrony, and concurrency.

Chapter 11 discusses the benefits of lazy evaluation and how lazy computations can be composed. This is a general pattern for which you’ll see several practical uses.

Chapter 12 shows how you can implement stateful programs without state mutation, and how stateful computations can also be composed.

Chapter 13 deals with asynchronous computations, and with how asynchrony can be combined with other effects discussed in previous parts of the book. This leads to the wider concern of combining several monadic effects—still an open topic of research in FP.

Asynchronous streams are even more general than asynchronous values, and they’re discussed in chapter 14, along with Rx, a framework for working with streams.

Finally, chapter 15 introduces message-passing concurrency, a style of lock-free concurrency that can be used when writing stateful concurrent programs.

Each chapter in part 3 introduces important techniques that have the potential to completely alter the way you think about writing software. Many of these topics are too vast to be discussed comprehensively, so these chapters aim to provide an introduction and a starting point for further exploration.