Functional Programming in Rust

The book "Functional Programming in Rust" is a practical guide for developers who want to master the functional programming style in the Rust ecosystem. Unlike many other languages, Rust natively supports functional programming concepts: closures, iterators, pattern matching, and a powerful type system. The author shows how to combine the functional approach with Rust's safety and performance.

Who is this book for?

• Developers familiar with the basics of Rust who want to deepen their knowledge of functional programming.
• Programmers from Scala, Haskell, or OCaml who want to bring functional practices to Rust.
• Engineers working with parallel and asynchronous systems, where the functional approach reduces the number of errors.
• Anyone who wants to write more predictable, testable, and modular code in Rust.

What will you learn?

• Fundamentals of functional programming: function purity, immutability, absence of side effects.
• Working with closures, iterators, and combinators (map, filter, fold, flat_map).
• Implementing functors, applicative functors, and monads in Rust using the Option, Result types, and custom types.
• Lazy evaluation and infinite sequences via iterators.
• Pattern matching and algebraic data types for safe error and state handling.
• Parallelism and concurrency with a functional approach: using Rayon, async/await, and channels.
• Function composition, currying, and partial application.
• Testing pure functions and managing state without mutations.

Book structure

The first part introduces fundamental concepts: why Rust is suitable for functional programming, how the ownership and borrowing system aligns with immutability. The second part focuses on iterators and closures—the main tools of the functional style. The third part covers advanced topics: functors, monads, lazy evaluation. The fourth part demonstrates the application of the functional approach in real projects: parsers, data processing, web servers. At the end of each chapter, there are exercises with solutions to reinforce the material.

Why should you read it?

• Learn to write code that is easier to understand and maintain.
• Reduce the number of bugs thanks to immutability and strict types.
• Master parallel programming without data races.
• Get ready-made patterns for common tasks: error handling, working with collections, asynchronous call chains.

The book contains over 100 code examples, ready to compile and run. All examples are accompanied by explanations and comparisons with the imperative style. After reading, you will be able to confidently apply functional techniques in everyday Rust development.