Book Image

Hands-On Functional Programming in RUST

By : Andrew Johnson
Book Image

Hands-On Functional Programming in RUST

By: Andrew Johnson

Overview of this book

Functional programming allows developers to divide programs into smaller, reusable components that ease the creation, testing, and maintenance of software as a whole. Combined with the power of Rust, you can develop robust and scalable applications that fulfill modern day software requirements. This book will help you discover all the Rust features that can be used to build software in a functional way. We begin with a brief comparison of the functional and object-oriented approach to different problems and patterns. We then quickly look at the patterns of control flow, data the abstractions of these unique to functional programming. The next part covers how to create functional apps in Rust; mutability and ownership, which are exclusive to Rust, are also discussed. Pure functions are examined next and you'll master closures, their various types, and currying. We also look at implementing concurrency through functional design principles and metaprogramming using macros. Finally, we look at best practices for debugging and optimization. By the end of the book, you will be familiar with the functional approach of programming and will be able to use these techniques on a daily basis.
Table of Contents (12 chapters)

Metaprogramming

Metaprogramming in Rust has two forms—macros and procedural macros. Both of these utilities accept an abstract syntax tree as new input and output symbols to be compiled. Procedural macros are very similar to normal macros but with fewer restrictions on how they work and how they are defined.

Macros defined with the macro_rules! syntax are defined recursively by matching the input syntax to produce output. It is crucial to understand that macro matching happens after parsing. This means the following:

  • Macros must follow certain rules when creating new syntax forms
  • The AST is decorated with information regarding each node's grammar category

Macros can match individual tokens, or a macro can match (and capture) an entire grammar category. The Rust grammar categories are as follows:

  • tt: This is a token tree (which is a token output from the lexer before...