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[TOC]
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# Introduction
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2022-07-14 00:57:18 +00:00
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Welcome to *The Rust Programming Language,* an introductory book about Rust.
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The Rust programming language helps you write faster, more reliable software.
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High-level ergonomics and low-level control are often at odds in programming
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language design; Rust challenges that conflict. Through balancing powerful
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technical capacity and a great developer experience, Rust gives you the option
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to control low-level details (such as memory usage) without all the hassle
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traditionally associated with such control.
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## Who Rust Is For
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Rust is ideal for many people for a variety of reasons. Let’s look at a few of
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the most important groups.
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### Teams of Developers
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Rust is proving to be a productive tool for collaborating among large teams of
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developers with varying levels of systems programming knowledge. Low-level code
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is prone to various subtle bugs, which in most other languages can be caught
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only through extensive testing and careful code review by experienced
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developers. In Rust, the compiler plays a gatekeeper role by refusing to
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compile code with these elusive bugs, including concurrency bugs. By working
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alongside the compiler, the team can spend their time focusing on the program’s
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logic rather than chasing down bugs.
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Rust also brings contemporary developer tools to the systems programming world:
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* Cargo, the included dependency manager and build tool, makes adding,
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compiling, and managing dependencies painless and consistent across the Rust
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ecosystem.
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* The Rustfmt formatting tool ensures a consistent coding style across
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developers.
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* The Rust Language Server powers Integrated Development Environment (IDE)
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integration for code completion and inline error messages.
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By using these and other tools in the Rust ecosystem, developers can be
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productive while writing systems-level code.
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### Students
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Rust is for students and those who are interested in learning about systems
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concepts. Using Rust, many people have learned about topics like operating
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systems development. The community is very welcoming and happy to answer
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student questions. Through efforts such as this book, the Rust teams want to
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make systems concepts more accessible to more people, especially those new to
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programming.
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### Companies
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Hundreds of companies, large and small, use Rust in production for a variety of
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tasks, including command line tools, web services, DevOps tooling, embedded
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devices, audio and video analysis and transcoding, cryptocurrencies,
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bioinformatics, search engines, Internet of Things applications, machine
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learning, and even major parts of the Firefox web browser.
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### Open Source Developers
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Rust is for people who want to build the Rust programming language, community,
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developer tools, and libraries. We’d love to have you contribute to the Rust
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language.
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### People Who Value Speed and Stability
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Rust is for people who crave speed and stability in a language. By speed, we
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mean both how quickly Rust code can run and the speed at which Rust lets you
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write programs. The Rust compiler’s checks ensure stability through feature
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additions and refactoring. This is in contrast to the brittle legacy code in
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languages without these checks, which developers are often afraid to modify. By
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striving for zero-cost abstractions, higher-level features that compile to
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lower-level code as fast as code written manually, Rust endeavors to make safe
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code be fast code as well.
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The Rust language hopes to support many other users as well; those mentioned
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here are merely some of the biggest stakeholders. Overall, Rust’s greatest
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ambition is to eliminate the trade-offs that programmers have accepted for
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decades by providing safety *and* productivity, speed *and* ergonomics. Give
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Rust a try and see if its choices work for you.
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## Who This Book Is For
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This book assumes that you’ve written code in another programming language but
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doesn’t make any assumptions about which one. We’ve tried to make the material
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broadly accessible to those from a wide variety of programming backgrounds. We
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don’t spend a lot of time talking about what programming *is* or how to think
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about it. If you’re entirely new to programming, you would be better served by
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reading a book that specifically provides an introduction to programming.
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## How to Use This Book
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In general, this book assumes that you’re reading it in sequence from front to
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back. Later chapters build on concepts in earlier chapters, and earlier
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chapters might not delve into details on a particular topic but will revisit
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the topic in a later chapter.
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You’ll find two kinds of chapters in this book: concept chapters and project
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chapters. In concept chapters, you’ll learn about an aspect of Rust. In project
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chapters, we’ll build small programs together, applying what you’ve learned so
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far. Chapters 2, 12, and 20 are project chapters; the rest are concept chapters.
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Chapter 1 explains how to install Rust, how to write a “Hello, world!” program,
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and how to use Cargo, Rust’s package manager and build tool. Chapter 2 is a
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hands-on introduction to writing a program in Rust, having you build up a
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number guessing game. Here we cover concepts at a high level, and later
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chapters will provide additional detail. If you want to get your hands dirty
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right away, Chapter 2 is the place for that. Chapter 3 covers Rust features
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that are similar to those of other programming languages, and in Chapter 4
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you’ll learn about Rust’s ownership system. If you’re a particularly meticulous
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learner who prefers to learn every detail before moving on to the next, you
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might want to skip Chapter 2 and go straight to Chapter 3, returning to Chapter
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2 when you’d like to work on a project applying the details you’ve learned.
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Chapter 5 discusses structs and methods, and Chapter 6 covers enums, `match`
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expressions, and the `if let` control flow construct. You’ll use structs and
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enums to make custom types in Rust.
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In Chapter 7, you’ll learn about Rust’s module system and about privacy rules
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for organizing your code and its public Application Programming Interface
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(API). Chapter 8 discusses some common collection data structures that the
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standard library provides, such as vectors, strings, and hash maps. Chapter 9
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explores Rust’s error-handling philosophy and techniques.
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Chapter 10 digs into generics, traits, and lifetimes, which give you the power
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to define code that applies to multiple types. Chapter 11 is all about testing,
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which even with Rust’s safety guarantees is necessary to ensure your program’s
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logic is correct. In Chapter 12, we’ll build our own implementation of a subset
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of functionality from the `grep` command line tool that searches for text
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within files. For this, we’ll use many of the concepts we discussed in the
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previous chapters.
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Chapter 13 explores closures and iterators: features of Rust that come from
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functional programming languages. In Chapter 14, we’ll examine Cargo in more
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depth and talk about best practices for sharing your libraries with others.
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Chapter 15 discusses smart pointers that the standard library provides and the
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traits that enable their functionality.
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In Chapter 16, we’ll walk through different models of concurrent programming
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and talk about how Rust helps you to program in multiple threads fearlessly.
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Chapter 17 looks at how Rust idioms compare to object-oriented programming
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principles you might be familiar with.
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Chapter 18 is a reference on patterns and pattern matching, which are powerful
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ways of expressing ideas throughout Rust programs. Chapter 19 contains a
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smorgasbord of advanced topics of interest, including unsafe Rust, macros, and
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more about lifetimes, traits, types, functions, and closures.
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In Chapter 20, we’ll complete a project in which we’ll implement a low-level
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multithreaded web server!
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Finally, some appendices contain useful information about the language in a
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more reference-like format. Appendix A covers Rust’s keywords, Appendix B
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covers Rust’s operators and symbols, Appendix C covers derivable traits
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provided by the standard library, Appendix D covers some useful development
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tools, and Appendix E explains Rust editions.
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There is no wrong way to read this book: if you want to skip ahead, go for it!
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You might have to jump back to earlier chapters if you experience any
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confusion. But do whatever works for you.
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An important part of the process of learning Rust is learning how to read the
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error messages the compiler displays: these will guide you toward working code.
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As such, we’ll provide many examples that don’t compile along with the error
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message the compiler will show you in each situation. Know that if you enter
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and run a random example, it may not compile! Make sure you read the
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surrounding text to see whether the example you’re trying to run is meant to
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error. In most situations, we’ll lead you to the correct version of any code
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that doesn’t compile.
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## Resources and How to Contribute to This Book
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2022-07-14 00:57:18 +00:00
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This book is open source. If you find an error, please don’t hesitate to file
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an issue or send a pull request on GitHub at
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*https://github.com/rust-lang/book/*. Please see *CONTRIBUTING.md* at
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*https://github.com/rust-lang/book/blob/main/CONTRIBUTING.md* for more details.
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The source code for the examples in this book, errata, and other information
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are available at *https://www.nostarch.com/Rust2021/*.
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