Programming Crystal: Create High-Performance, Safe, Concurrent Apps

https://pragprog.com/book/crystal/programming-crystal

A book written by Ivo Balbaert and Simon St. Laurent

Crystal is for Ruby programmers who want more performance or for developers who enjoy working in a high-level scripting environment. Crystal combines native execution speed and concurrency with Ruby-like syntax, so you will feel right at home. This book, the first available on Crystal, shows you how to write applications that have the beauty and elegance of a modern language, combined with the power of types and modern concurrency tooling. Now you can write beautiful code that runs faster, scales better, and is a breeze to deploy.