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

Calculating when you can retire


If you have tried to call simulatePlan from the Scala Console, you probably tried different values for nbOfMonths and observed the resulting capital at retirement and after death. It would be useful to have a function that finds the optimal nbOfMonths so that you have enough capital to never run out of money during your retirement.

Writing a failing test for nbOfMonthsSaving

As usual, let's start with a new unit test to clarify what we expect from this function:

"RetCalc.nbOfMonthsSaving" should {
"calculate how long I need to save before I can retire" in {
val actual = RetCalc.nbOfMonthsSaving(
      interestRate = 0.04 / 12, nbOfMonthsInRetirement = 40 * 12,
netIncome = 3000, currentExpenses = 2000, initialCapital = 10000)
val expected = 23 * 12 + 1
actual should ===(expected)
  }
}

In this test, the expected value can be a bit difficult to figure out. One way would be to use the NPM function in Excel. Alternatively, you could call simulatePlan many times in...