Book Image

Scala Programming Projects

By : Mikael Valot, Nicolas Jorand
Book Image

Scala Programming Projects

By: Mikael Valot, Nicolas Jorand

Overview of this book

Scala Programming Projects is a comprehensive project-based introduction for those who are new to Scala. Complete with step-by-step instructions and easy-to-follow tutorials that demonstrate best practices when building applications, this Scala book will have you building real-world projects in no time. Starting with the fundamentals of software development, you’ll begin with simple projects, such as developing a financial independence calculator, and then advance to more complex projects, such as a building a shopping application and a Bitcoin transaction analyzer. You’ll explore a variety of Scala features, including its OOP and FP capabilities, and learn how to write concise, reactive, and concurrent applications in a type-safe manner. You’ll also understand how to use libraries such as Akka and Play. Furthermore, you’ll be able to integrate your Scala apps with Kafka, Spark, and Zeppelin, along with deploying applications on a cloud platform. By the end of the book, you’ll have a firm foundation in Java programming that’ll enable you to solve a variety of real-world problems, and you’ll have built impressive projects to add to your professional portfolio.
Table of Contents (18 chapters)
Title Page
Copyright and Credits
Packt Upsell
Contributors
Preface
Index

Using Option


The Scala Option type is an algebraic data type (ADT) that represents an optional value. It can also be viewed as List that can contain either one or no elements. It is a safe replacement for a null reference that you might have used if you have programmed in Java, C++, or C#.

Manipulating instances of Option

The following is a simplified definition of the Option ADT:

sealed trait Option[+A]
case class Some[A](value: A) extends Option[A]
case object None extends Option[Nothing]

The Scala SDK provides a more refined implementation; the preceding definition is just for illustrative purpose. This definition implies that Option can be either of the following two types:

  • Some(value), which represents an optional value where the value is present
  • None, which represents an optional value where the value is not present.

Note

The + sign in front of the A type parameter in the Option[+A] declaration means that Option is covariant in A. We will explore contravariance in more details in Chapter...