Functional Programming in PHP: From Basics to Advanced Techniques

The book "Functional Programming in PHP" is a practical guide to implementing the functional programming (FP) paradigm in everyday PHP development. Unlike typical textbooks, this book doesn't just list theoretical concepts but shows how to apply them to solve real-world problems: from data processing to building web application architecture.

The author, Alexey Smirnov, is a senior developer with 10 years of experience, specializing in high-load projects using PHP and Symfony. In the book, he shares proven patterns that will help you write code that is resilient to errors and easy to maintain.

What you will learn from the book:

• FP Basics in PHP: pure functions, data immutability, absence of side effects.
• Working with Higher-Order Functions: map, filter, reduce, function composition, partial application, and currying.
• Monads and Functors: practical use of Maybe, Either, IO monads for error handling and asynchronicity without exceptions.
• Lazy Evaluation and Generators: optimizing work with large datasets and infinite sequences.
• Functional Architecture: building applications using monad transformers, free monads, and effect systems.
• Integration with Existing Projects: how to gradually introduce functional approaches into legacy PHP code.

Who this book is for:

• Middle-level and above PHP developers familiar with OOP who want to expand their toolkit.
• Architects designing complex systems where code predictability and testability are important.
• Anyone who wants to understand how functional programming can improve the quality of PHP code without switching to other languages.

The book contains numerous code examples, from simple functions to full-fledged mini-projects. You will learn to avoid "dirty" states, easily test business logic, and build composable abstractions. After reading it, you will be able to write elegant, declarative PHP code that is not afraid of changes.

Edition feature: all examples are adapted for modern PHP versions (8.1+), using built-in language features (arrow functions, union types, match expressions) and popular libraries (vazaha-nl/php-functional, loophp/collection).

This is not just a book — it is your guide to a world where PHP becomes a language capable of elegant functional solutions. Discover a new way of thinking about code.