| # Functional Language Features: Iterators and Closures |
| |
| Rust’s design has taken inspiration from many existing languages and techniques, |
| and one significant influence is _functional programming_. Programming in a |
| functional style often includes using functions as values by passing them in |
| arguments, returning them from other functions, assigning them to variables for |
| later execution, and so forth. |
| |
| In this chapter, we won’t debate the issue of what functional programming is or |
| isn’t but will instead discuss some features of Rust that are similar to |
| features in many languages often referred to as functional. |
| |
| More specifically, we’ll cover: |
| |
| * _Closures_, a function-like construct you can store in a variable |
| * _Iterators_, a way of processing a series of elements |
| * How to use closures and iterators to improve the I/O project in Chapter 12 |
| * The performance of closures and iterators (Spoiler alert: they’re faster than |
| you might think!) |
| |
| We’ve already covered some other Rust features, such as pattern matching and |
| enums, that are also influenced by the functional style. Because mastering |
| closures and iterators is an important part of writing idiomatic, fast Rust |
| code, we’ll devote this entire chapter to them. |
