# The Rust Programming Language

by Steve Klabnik and Carol Nichols, with contributions from the Rust Community

Welcome to The Rust Programming Language book! This version of the text assumes you’re using Rust 1.31.0 or later with `edition="2018"` in Cargo.toml of all projects to use Rust 2018 Edition idioms. See the “Installation” section of Chapter 1 to install or update Rust, and see the new Appendix E for information on what editions of Rust are.

The 2018 Edition of the Rust language includes a number of improvements that make Rust more ergonomic and easier to learn. This printing of the book contains a number of changes to reflect those improvements:

- Chapter 7, “Managing Growing Projects with Packages, Crates, and Modules,” has been mostly rewritten. The module system and the way paths work in the 2018 Edition were made more consistent.
- Chapter 10 has new sections titled “Traits as Parameters” and “Returning Types that Implement Traits” that explain the new `impl Trait` syntax.
- Chapter 11 has a new section titled “Using `Result<T, E>` in Tests” that shows how to write tests that use the `?` operator.
- The “Advanced Lifetimes” section of Chapter 19 was removed because compiler improvements have made the constructs in that section even rarer.
- The previous Appendix D, “Macros,” has been expanded to include procedural macros and was moved to the “Macros” section in Chapter 19.
- Appendix A, “Keywords,” also explains the new raw identifiers feature that enables code written in the 2015 Edition and the 2018 Edition to interoperate.
- Appendix D is now titled “Useful Development Tools” and covers recently released tools that help you write Rust code.
- We fixed a number of small errors and imprecise wording throughout the book. Thank you to the readers who reported them!

Note that any code in the first printing of The Rust Programming Language that compiled will continue to compile without `edition="2018"` in the project’s Cargo.toml, even as you update the Rust compiler version you’re using. That’s Rust’s backward compatibility guarantees at work!

The HTML format is available online at https://doc.rust-lang.org/stable/book/ and offline with installations of Rust made with `rustup`; run `rustup docs --book` to open.

This text is available in paperback and ebook format from No Starch Press.