Book Image

Crystal Programming

By : George Dietrich, Guilherme Bernal
Book Image

Crystal Programming

By: George Dietrich, Guilherme Bernal

Overview of this book

Crystal is a programming language with a concise and user-friendly syntax, along with a seamless system and a performant core, reaching C-like speed. This book will help you gain a deep understanding of the fundamental concepts of Crystal and show you how to apply them to create various types of applications. This book comes packed with step-by-step explanations of essential concepts and practical examples. You'll learn how to use Crystal’s features to create complex and organized projects relying on OOP and its most common design patterns. As you progress, you'll gain a solid understanding of both the basic and advanced features of Crystal. This will enable you to build any application, including command-line interface (CLI) programs and web applications using IOs, concurrency and C bindings, HTTP servers, and the JSON API. By the end of this programming book, you’ll be equipped with the skills you need to use Crystal programming for building and understanding any application you come across.
Table of Contents (26 chapters)
1
Part 1: Getting Started
5
Part 2: Learning by Doing – CLI
10
Part 3: Learn by Doing – Web Application
13
Part 4: Metaprogramming
18
Part 5: Supporting Tools

Scaffolding the project

The first thing we need to do is initialize a new project that'll contain the code for the application. Crystal offers an easy way to do this via the crystal init command. This command will create a new folder, scaffold out a basic set of files, and initialize an empty Git repository. The command supports creating both app and lib type projects, with the only difference being that lib projects also have the shard.lock file ignored via .gitignore, with the reason being the dependencies will be locked via the application using the project. Given we won't have any external shared dependencies and we'll eventually want to allow the project to be included in other Crystal projects, we're going to create a lib project.

Start by running crystal init lib transform within your terminal. This will initialize a library project called transform, with the following directory structure (Git-related files omitted for brevity):

.
├─&...