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 Either


The Either type is an ADT that represents a value of either a Left type or a Right type. A simplified definition of Either would be the following:

sealed trait Either[A, B]
case class Left[A, B](value: A) extends Either[A, B]
case class Right[A, B](value: B) extends Either[A, B]

When you instantiate a Right type, you need to provide a value of a B type, and when you instantiate aLeft type, you need to provide a value of anA type. Therefore, Either[A, B]can either hold a value of typeAor a value of typeB.

The following code shows an example of such a usage that you can type in a new Scala worksheet:

def divide(x: Double, y: Double): Either[String, Double] =
if (y == 0)
Left(s"$x cannot be divided by zero")
else
Right(x / y)

divide(6, 3)
// res0: Either[String,Double] = Right(2.0)
divide(6, 0)
// res1: Either[String,Double] = Left(6.0 cannot be divided by zero)

The divide function returns either a string or a double:

  • If the function cannot compute a value, it returns an error String...