Andrew Johnson - Hands-On Functional Programming in Rust

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Andrew Johnson is a software developer who has worn many hats. Professionally, he has worked on projects written in C, C++, Java, Python, Ruby, JavaScript, Haskell, OCaml, and now Rust. Most notably, he has worked as an early employee at Topsy Labs (acquired by Apple) and FiscalNote (growing rapidly). Academically, his interests are focused on the intersection between formal language processing (such as programming languages) and existing natural language programming techniques.

Sebastian Drge is a free software developer currently working with Centricular Ltd. He has been involved for more than 10 years with the GStreamer project, a cross-platform multimedia framework. He also contributes to various other projects, such as Debian, GNOME, Rust, and WebKit. While finishing his master's degree in computer science, he started working as a contractor on free software and continues to do so to this day.

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Thanks for your interest in functional programming in Rust. Rust is a very young programming language and is particularly new to the functional programming community. Despite its age, the language provides a wealth of tools that are both practical and sophisticated.

In this book, we will introduce general functional programming principles and how they apply to Rust specifically. Our goal is to provide knowledge and a perspective on Rust that will outlast small changes to language features. The pace of development of Rust is so fast that during the course of writing the book we introduced new features as they became available and relevant. We want to equip the reader to produce code for this fast-moving environment such that they are prepared to best utilize new features as they are released.

This book is for developers who are familiar with basic Rust features or are willing to reference other material as they read along. We will not fully explain every new symbol, library, or syntax form, but we do explain libraries that are considered more advanced or syntax that may be difficult to read. Similarly, some concepts that are only briefly explained in the introductory material will be explained in detail.

, Functional Programming a Comparison , introduces functional programming in Rust. Comparisons are drawn between functional style and other paradigms that are prevalent or influential to Rust. The chapter also serves as a brief outline of topics that will appear later in the book.

, Functional Control Flow , introduces Rust control flow structures while explaining how they are relevant to the functional style of programming. The expression-centric nature of functional programming and Rust is illustrated through examples. Limiting as it may be, the chapter also begins an ongoing project using only the procedural expression style of programming.

, Functional Data Structures , introduces the reader to the various, highly expressive data types available in Rust. Notably, the enum type is introduced, which holds particular significance in functional programming. The project continues to grow to incorporate a variety of these data types.

, Generics and Polymorphism , explains the concepts of parameterization of data (generics) and parameterization of control flow (polymorphism). Parameterization and its natural interaction with traits reduces the programmer's burden, but the syntax can become overwhelming. Some approaches to reduce or mitigate parameter explosion are introduced. The ongoing project again grows to incorporate these features.