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Scala Programming Projects
Scala Programming Projects

Scala Programming Projects: Build real-world projects using popular Scala frameworks such as Play, Akka, and Spark

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Profile Icon Valot Profile Icon Nicolas Jorand
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Full star icon Full star icon Full star icon Half star icon Empty star icon 3.8 (5 Ratings)
Paperback Sep 2018 398 pages 1st Edition
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Arrow left icon
Profile Icon Valot Profile Icon Nicolas Jorand
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Full star icon Full star icon Full star icon Half star icon Empty star icon 3.8 (5 Ratings)
Paperback Sep 2018 398 pages 1st Edition
eBook
₱1571.99 ₱2245.99
Paperback
₱2806.99
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eBook
₱1571.99 ₱2245.99
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₱2806.99
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Scala Programming Projects

Developing a Retirement Calculator

In this chapter, we will put 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 and how much to save to have a comfortable retirement.

We will use the test-driven development (TDD) technique to develop the different functions. I encourage you to try writing the body of the functions yourself before looking at the solution. Also, it would be better to retype the code rather than copy/pasting it. You will remember it more and will have a sense of what it feels like to use IntelliJ's completion and editor. Do abuse the autocompletion with Ctrl + spacebar. You will not only type faster, but you will also discover what functions are...

Project overview

Using some parameters such as your net income, your expenses, your initial capital, and so on, we will create functions to calculate the following:

  • Your future capital at retirement
  • Your capital after a number of years in retirement
  • How long you need to save to be able to retire

We will first use a fixed interest rate for these calculations. After that, we will load market data from .tsv files, then refactor the previous functions to simulate what could happen during the investment period.

Calculating the future capital

The first thing you need to know when planning for retirement is how much capital you can get at your chosen retirement date. For now, we will assume that you invest your savings every month at a constant rate. To simplify things, we will ignore the effects of inflation, hence the capital calculated will be in today's money and the interest rate will be calculated as real rate = nominal interest rate - inflation rate.

We intentionally do not mention any currency in the rest of this chapter. You can consider that the amounts are in USD, EUR, or any other currency. It will not change the results as long as all the amounts are expressed in the same currency.

Writing a unit test for the accumulation phase

...

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...

Using market rates

In our calculations, we have always assumed that the interest rate of return was constant, but the reality is more complex. It would be more accurate to use real rates from market data to gain more confidence with our retirement plan. For this, we first need to change our code to be able to perform the same calculations using variable interest rates. Then, we will load real market data to simulate regular investments in a fund by tracking the S & P 500 index.

Defining an algebraic data type

In order to support variable rates, we need to change the signature of all functions that accept interestRate: Double. Instead of a double, we need a type that can represent either a constant rate or a sequence of...

Packaging the application

We have now implemented some useful building blocks, and it is time to create an executable so that end users can use our calculator with their own parameters.

Creating the App object

We are going to build a simple executable around RetCalc.simulatePlan. It will take a list of parameters separated by spaces, and print the results on the console.

The test we are going to write integrates several components together and will use a full market data set. As such, it is not really a unit test anymore; it is an integration test. For this reason, we suffixed it with IT instead of Spec.

First, copy sp500.tsv and cpi.tsv from https://github.com/PacktPublishing/Scala-Programming-Projects/blob/master...

Summary

We have covered how to create a small project in Scala from scratch to packaging. We used TDD along the way so that it is guaranteed that our code was well-designed and robust. It gives us confidence when we refactor code: as long as all tests pass, we know that our code stills works. We modeled our domain with immutable data structures and processed them using pure functions that have no side effects.

We used some basic features of the language that are used in most projects, and you should now be familiar with enough building blocks to implement a wide variety of projects.

As a further exercise, you could enhance this calculator with one or many of these features:

  • Create an app for the function RetCalc.nbOfMonthsSaving, which calculates how long you need to save before you can retire.
  • Create a function called RetCalc.annualizedTotalReturn, which calculates...
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Key benefits

  • Develop Scala projects on topics ranging from web applications to big data analysis
  • Unleash the full power of modern web programming using Play Framework
  • Build real-time data pipelines in Scala with a Bitcoin transaction analysis app

Description

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.

Who is this book for?

If you’re new to programming and want to learn how to use Scala, this book is for you. Though not necessary, some knowledge of Java will help you understand the concepts covered in this book.

What you will learn

  • Build, test, and package code using sbt (Scala Build Tool)
  • Decompose code into functions, classes, and packages for maintainability
  • Implement the functional programming capabilities of Scala
  • Develop a simple CRUD REST API using Play Framework
  • Access a relational database using Slick
  • Develop a dynamic web UI using Scala.js
  • Source streaming data using Spark Streaming and write a Kafka producer
  • Use Spark and Zeppelin to analyze data

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Length: 398 pages
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Language : English
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Product Details

Publication date : Sep 29, 2018
Length: 398 pages
Edition : 1st
Language : English
ISBN-13 : 9781788397643
Category :
Languages :
Tools :

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Table of Contents

12 Chapters
Writing Your First Program Chevron down icon Chevron up icon
Developing a Retirement Calculator Chevron down icon Chevron up icon
Handling Errors Chevron down icon Chevron up icon
Advanced Features Chevron down icon Chevron up icon
Type Classes Chevron down icon Chevron up icon
Online Shopping - Persistence Chevron down icon Chevron up icon
Online Shopping - REST API Chevron down icon Chevron up icon
Online Shopping - User Interface Chevron down icon Chevron up icon
Interactive Browser Chevron down icon Chevron up icon
Fetching and Persisting Bitcoin Market Data Chevron down icon Chevron up icon
Batch and Streaming Analytics Chevron down icon Chevron up icon
Other Books You May Enjoy Chevron down icon Chevron up icon

Customer reviews

Rating distribution
Full star icon Full star icon Full star icon Half star icon Empty star icon 3.8
(5 Ratings)
5 star 40%
4 star 20%
3 star 20%
2 star 20%
1 star 0%
Melvin Apr 03, 2021
Full star icon Full star icon Full star icon Full star icon Full star icon 5
This is in my opinion the best scala book out there to start your journey with. I have looked at quite a few scala books and some are good but take forever to get to so called advanced concepts. This book gets you up to speed with programming concepts unique to scala without needing to read over a thousand pages first. Additionally, this book incorporated the use of intellij IDE which can be a pain when you first start using scala. The other thing that I liked about the book is that the projects show you how to tackle various problems by writing in the scala style of the functional programming. I think this book probably was the most useful scala book I have ever bought.
Amazon Verified review Amazon
Misha Tavkhelidze Jan 12, 2019
Full star icon Full star icon Full star icon Full star icon Full star icon 5
Excellent book to start your Scala journey. Read it before jumping to more advanced, say, Functional Programming in Scala.Apart from introducing the language (and FP paradigm) from very basic to comparatively advanced aspects, the book also teaches you how to set up projects using standard build tools and frameworks, which I found to be invaluable for someone who is new to the whole eco-system.Some familiarity with the language itself is nessesary, but, I believe, not required.
Amazon Verified review Amazon
Cameron Smith Sep 03, 2019
Full star icon Full star icon Full star icon Full star icon Empty star icon 4
Good introduction to specific frameworks, approaches and libraries for someone who already knows Scala.Opinionated but justifies his opinions based on realistic project examples, rather than just ranting.Still have not finished the book - because every two pages give a wealth of examples and ideas to try out.
Amazon Verified review Amazon
Amazon Customer Aug 08, 2019
Full star icon Full star icon Full star icon Empty star icon Empty star icon 3
Books does not teach you scala. Project descriptions not best but enough. That is book for people that have learned scala, akka etc and looking for good project example and some example how things are done in scala ecosystem.
Amazon Verified review Amazon
Mark Tanser Jul 09, 2019
Full star icon Full star icon Empty star icon Empty star icon Empty star icon 2
The overall content and exercises are fine, but it is dogged by typos and omissions which render it a huge struggle to follow for a beginner. Without consulting the online code on gitHub it would be impossible to complete the sections. There are also code exceptions and errors which are not covered in the text and you're left to search for answers on Stackoverflow. Really, a book like this should be thoroughly proof-read and tested by a first-sight user going through the instructions cover-to-cover, before committing to print and offering for sale.
Amazon Verified review Amazon
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