This book is designed to help PHP programmers, whether experienced or looking to advance, transition into the world of Functional Programming (FP). It covers the key concepts and practical applications of FP in PHP, with a particular focus on function composition. By introducing ideas like immutability, referential transparency, and the role of functions in abstraction and generalization, the book aims to give readers the fundamental knowledge necessary to incorporate FP principles into their PHP projects. The book distills the theoretical foundations of paradigmatic concepts such as functors, monads, lenses, pattern matching, and recursion, ideas congruent with the rationale of composing functions, into comprehensive segments that each offer demonstrations of how to apply them in solving problems that occur in everyday PHP development. So robustly intuitive are the demonstrations of paradigmatic concepts that they can easily be revised for deployment in more elaborate and often complex language codebases. In offering these, the book equips its readers to favor composition when designing solutions to challenging problems. Additionally, the book dispels common misconceptions about FP, describes the paradigm’s influence on the creation of commonplace programming ideas that, at a glance, might not seem related to it, and explores how it can be integrated with other programming paradigms. Emphasized throughout the book are the benefits of creating and using higher-order abstractions, which instate composable error handling, rigorous testing, and lazy flow control. The goal is to help readers develop a deeper understanding of FP, enabling them to incorporate its powerful patterns into their everyday programming practice and elevate their technical proficiency. You Will Learn: The foundations of functional programming and the potency of composition. How to apply advanced patterns like partial application, currying, and transducers in PHP projects. How to speed...