3.8 Summary

In this chapter, we looked again at writing pure functions free of side effects. We looked at generator functions and how we can use these as the backbone of functional programming to process collections of items. We also examined a number of the built-in collection classes to show how they’re used in the functional paradigm. While the general idea behind functional programming is to limit the use of stateful variables, the collection objects have a stateful implementation. For many algorithms, they’re often essential. Our goal is to be judicious in our use of Python’s non-functional features.

In the next two chapters, we’ll look at functions for processing collections. After that, we’ll look closely at higher-order functions: functions that accept functions as arguments as well as returning functions. In later chapters, we’ll look at techniques for defining our own higher-order functions. We’ll also look at the itertools and...