Daniel Westheide - Scala from Scratch: Exploration

In the last few years, Scala and a bunch of technologies based on it have gained a lot of traction. Some of these technologies became crucial for dealing with big and fast data. Others paved the way when it comes to building resilient, scalable applications. As a consequence, Scala became very popular in startups living on the bleeding edge. In the wake of this, even big, conservative enterprises have been adopting it more and more.

Scala stands on the shoulders of the Java Virtual Machine (JVM). Developers can integrate with the vast pool of great libraries the Java ecosystem has to offer. Since shortly after its inception, it has been leading the way on the JVM when it comes to combining the object-oriented and functional programming paradigm. We have seen Java adopt functional language features that have proven to be a great success in Scala. Also, new languages like Kotlin emerged that take a lot of inspiration from Scala.

While Java and others have been following suit at their own pace, Scala continues to be the forerunner on the JVM. It provides one of the most sophisticated type systems in mainstream programming languages. As such, its a great tool for writing safe, concurrency-friendly code that is easy to test, in a succinct way.

Scala originated on the JVM, but these days its available for two alternative targets as well: Scala.js compiles to JavaScript, where as Scala Native allows you to write native applications, using LLVM.

This book is the first one in the Scala from Scratch series. It will give you a strong foundation and a comprehensive overview of what Scala brings to the table. The goal is to get you excited about the language and to give you an idea of what its like to work with Scala. By the end of the book, you should be able to write small Scala programs on your own. Well show how to do that by walking through a small, but complete example application.

If you are hungry for more, you can continue your journey in the second book, Scala from Scratch: Understanding. It will explain many of the concepts introduced in this book in more depth, and it will cover concepts and language features that are too advanced for an introductory book.

While Scala.js and Scala Native have gained a bit of traction, this book and the follow-up book focus solely on Scala for the JVM, which is where Scala is most popular.

This book is mainly targeted at people who are already somewhat familiar with an object-oriented and imperative language like Java, Ruby, or Python whether you are a student, a software engineer, or a data scientist.

You should know a thing or two about the tools in your languages ecosystem. Yet you dont have to be an experienced software engineer. Were using the command-line. Some basic familiarity with how to execute commands in your operating systems command-line interface would be nice.

Experience with some typical object-oriented design patterns is helpful, but not required.

You neednt know anything about functional programming before reading this book. All you need is an open mind and the willingness to leave your comfort zone and think outside the box.

I wrote this book as a text book. Its best to read it from the first to the last chapter. This is by no means a language reference. However, it should be easy for you to get back to any chapter or section in the future if you want to refresh your knowledge on a specific topic.

Youll get the most out of this book by trying out all the examples that I use to explain new concepts. Besides, many, but not all the sections in this book contain a few exercises that you can work on by yourself. If you do, youll get new insights about what you have learned. Nothing in the book requires for you to have tackled a previous exercise. Even so, its recommended to spend some time with these exercises before moving on to the next section.

This book makes use of the following typographical conventions:

• Italic text is used when introducing a new term, as well as for emphasis
• Constant width text is used for program listings, for references to code elements, file and directory names, and for shell commands or program output
• In program listings, a $ at the beginning of the line tells you that you are in a shell in your terminal, for example bash or zsh

If you spot any typos, factual errors, or other problems, please take the time to inform me about it. The best way to do that is the LeanPub feedback form.

If you like this book, I would be grateful if you could spread the word. Please tell your friends, share it on Twitter or other social media channels, or publish a review. A great place to do that is the books GoodReads page.

Daniel Westheide is a software engineer living in Berlin, Germany. He is a senior consultant at INNOQ and co-organiser of ScalaBridge Berlin, the Berlin chapter of the ScalaBridge organisation. He cares about empathy and inclusivity, and about the ethical, social, and ecological consequences of his work.

On his website, he discusses functional programming, architecture, as well as anything related to the software development process. He is not only interested in programming languages, but also a human language enthusiast. Moreover, he is passionate about specialty coffee, social science fiction, and tabletop roleplaying games.

Thanks a lot to Lars Hupel, Stefan Lauer, Timo Loist, Martin Otten, Lara Pourabdolrahim, Nicolas Rinaudo, Tina Schnborn, Jan Stpie and everyone I have forgotten for giving me valuable feedback, proofreading, and being my rubber duck when I needed one.