In this section, we will learn about the basic building blocks of functional programming and how to use them in C++. First, we will look at what functional programming is and how it is different from and similar to object-oriented programming (OOP). Then, we will dive into the fundamental idea of immutability and learn how to write pure functions in C++—that is, functions that don't change state. We will then learn how to use lambdas and how to write pure functions using them.

Once we master those building blocks, we can move on to operations with functions. In functional programming, functions are data, so we can pass them around and make operations with them. We will learn about partial application and currying, two fundamental and closely-related operations. We will also see how to compose functions. These operations will take us from simple functions to very complex ones with just a few lines of plumbing code.

The following chapters will be covered in this section:

• Chapter 1, An Introduction to Functional Programming
• Chapter 2, Understanding Pure Functions
• Chapter 3, Deep Dive into Lambdas
• Chapter 4, The Idea of Functional Composition
• Chapter 5, Partial Application and Currying