Scala is a type-safe JVM language that incorporates object-oriented programming (OOP) and functional programming (FP) aspects. This book gets you started with the essentials of software development by guiding you through the different aspects of Scala programming, helping you bridge the gap between learning and implementing. You will learn about the unique features of Scala through diverse applications and encounter simple yet powerful approaches for software development. You will see how to use the basic tools, set up the environment, and write Scala programs.
Scala Programming Projects will help you build a number of applications, beginning with a simple project, such as a financial independence calculator, and advancing to other projects, such as a shopping application or a Bitcoin transaction analyzer. You will be able to use various Scala features, such as its OOP and FP capabilities, and learn ways to write concise, reactive, and concurrent applications in a type-safe manner. You will also learn how to use top-notch libraries, such as Akka and Play, and integrate Scala applications with Kafka, Spark, and Zeppelin; plus, you'll explore deploying applications on cloud platforms.
By the end of the book, you will be empowered by knowing the ins and outs of Scala, being able to apply Scala to solve a variety of real-world problems.
If you are an amateur programmer who wishes to learn how to use Scala, this book is for you. Knowledge of Java would be beneficial for, but is not necessary to, understanding the concepts covered in this book.
Chapter 1, Writing Your First Program, explains how to set up your environment to start programming in Scala, covering the basic tools that are required and what the simplest Scala application might look like.
Chapter 2, Developing a Retirement Calculator, puts into practice the features of the Scala language seen in the first chapter. We will also introduce other elements of the Scala language and SDK to develop the model and logic for a retirement calculator. This calculator will help people work out how long they'll need to save and how much they'll need to save to have a comfortable retirement.
Chapter 3, Handling Errors, has you continuing to work on the retirement calculator from the previous chapter, handling the errors that riddle it. For instance, the calculator works correctly as long as the right arguments are passed to it but fails badly with a horrible stack trace if any of the parameters are wrong.
Chapter 4, Advanced Features, explores the more advanced features of Scala. As with any programming language, some advanced constructs might be seldom used in practice or can obfuscate code. We will aim to only explain features that we have encountered in real projects that have been deployed to production.
Chapter 5, Type Classes, you will learn what a type class is, what are the most common type classes in the cats library, and how to use them in your projects.
Chapter 6, Online Shopping – Persistence, explains how to persist data in a relational database. The data will be the contents of a cart for a shopping website.
Chapter 7, Online Shopping – REST API, covers how to develop a REST API using Play Framework. API is an acronym for Application Programming Interface, and the acronym REST stands for Representational State Transfer. Basically, we will provide an interface for our application, so that other programs can interact with it.
Chapter 8, Online Shopping – User Interface, gets you using Scala.js to build the user interface for the online shopping application. In this interface, you will be able to select a product to add to your cart, update the number of products that you wish to buy, and remove them from the cart if needed.
Chapter 9, Interactive Browser, introduces the actor model by extending our shopping project. The extension will consist of a notification, provided to anyone connected to the website, about who is adding/removing a product to/from the cart.
Chapter 10, Fetching and Persisting Bitcoin Market Data, look at developing a data pipeline to fetch, store, and analyze Bitcoin transaction data. We will use Apache Spark in batch mode to do so.
Chapter 11, Batch and Streaming Analytics, focuses on how to use Zeppelin and Spark to query our historical data store. We will use Zeppelin's capability to plot interesting graphs and Apache Kafka with Spark streaming to analyze live transactions.
Basic knowledge of any programming language would be helpful to you during the course of this book. Additional knowledge of Java would also be useful for understanding some concepts covered in this book. There are several levels of involvement to make the most of this book, from the quickest to the most effective:
- You can just read it and look at the code in your IDE.
- While you read it, you can copy and paste the code samples in your IDE and run them.
- Same as before, but this time you re-type all the code samples. Using the auto-completion will make you discover more functions of the API. Typing the code will also make you remember it more. You make use of your visual and kinesthetic memory.
- The Benjamin Franklin method. You read a whole chapter or a section in one go, then close the book. After that, try to re-write the code samples from memory. If you are stuck you can reopen the book. This will force your brain to have a complete picture of a project. You will memorize and understand the concepts in much more depth.
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class LazyDemo {
lazy val lazyVal = {
println("Evaluating lazyVal")When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:
def lazyEvenPlusOne(xs: Vector[Int]): Vector[Int] =
xs.withFilter { x => println(s"filter $x"); x % 2 == 0 }Any command-line input or output is written as follows:
$ mkdir css $ cd css
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