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- Herausgeber: Packt Publishing
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
If your application source code is overly verbose, it can be a nightmare to maintain. Write concise and expressive, type-safe code in an environment that lets you build for the JVM, browser, and more.
Key Features
- Expert guidance that shows you to efficiently use both object-oriented and functional programming techniques
- Understand functional programming libraries, such as Cats and Scalaz, and use them to augment your Scala development
- Perfectly balances theory and hands-on exercises, assessments, and activities
Book Description
This book teaches you how to build and contribute to Scala programs, recognizing common patterns and techniques used with the language. You'll learn how to write concise, functional code with Scala. After an introduction to core concepts, syntax, and writing example applications with scalac, you'll learn about the Scala Collections API and how the language handles type safety via static types out-of-the-box. You'll then learn about advanced functional programming patterns, and how you can write your own Domain Specific Languages (DSLs). By the end of the book, you'll be equipped with the skills you need to successfully build smart, efficient applications in Scala that can be compiled to the JVM.
What you will learn
- Understand the key language syntax and core concepts for application development
- Master the type system to create scalable type-safe applications while cutting down your time spent debugging
- Understand how you can work with advanced data structures via built-in features such as the Collections library
- Use classes, objects, and traits to transform a trivial chatbot program into a useful assistant
- Understand what are pure functions, immutability, and higher-order functions
- Recognize and implement popular functional programming design patterns
Who this book is for
This is an ideal book for developers who are looking to learn Scala, and is particularly well suited for Java developers looking to migrate across to Scala for application development on the JVM.
Das E-Book können Sie in Legimi-Apps oder einer beliebigen App lesen, die das folgende Format unterstützen:
Seitenzahl: 199
Veröffentlichungsjahr: 2018
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Table of Contents
Professional Scala
Professional Scala
Copyright © 2018 Packt Publishing
All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.
Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the authors, nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book.
Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.
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Development Editor: Murtaza Haamid
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First published: July 2018
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Published by Packt Publishing Ltd.
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ISBN: 978-1-78953-383-5
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Contributors
About the Authors
Mads Hartmann is a software engineer with a fondness for automation and programming languages, especially statically typed functional ones. He holds a masters degree in computer science from the University of Copenhagen and he is currently working as a full-stack engineer at Family.
He is active in the Copenhagen developer scene and he has organized a meetup group for people interested in Scala and co-organized a meetup group for people generally interested in programming languages.
Ruslan Shevchenko is a system architect and a software developer who is focused on building reliable software systems. He specializes in programming languages and frameworks such as Scala, Java (J2SE, J2EE, Android), O/R Mapping, C++ , C, JavaScript, Perl, Tcl, and TermWare.
The domains he specializes in are telecommunications, OSS/billing systems, finance, code analysis, social integration, system utilities architecture domains, large-scale software systems, and distributed processing.
In terms of architecture, his specialist domains are large-scale software systems and distributed processing.
Preface
Scala is a type-safe JVM language that incorporates both object-oriented and functional programming into an extremely concise, logical, and extraordinarily powerful language. Some may be surprised to know that Scala is not quite as new as they may have thought, having first been introduced in 2003. However, it is in the past few years in particular that Scala has begun to develop a significant following.
This book enables you to build and contribute to Scala programs, recognizing common patterns and techniques used with the language.
This is a practical book which provides you with a lot of hands-on experience with Scala.
Who This Book Is For
This book is for developers who are interested in learning about the advanced features of the Scala language. Basic knowledge of the Scala programming language is required to follow the instructions in this book.
What This Book Covers
Chapter 1, Setting up the Development Environment, shows you how to set up your development environment. You'll learn the basics of Scala, such as what the simple Scala program looks like and what a typical developer flow is. It'll also cover some aspects of testing your Scala program by using unit testing.
Chapter 2, Basic Language Features, covers classes and objects, traits, pattern matching, case class, and so on. You'll also implement your chatbot application by applying the object oriented concepts.
Chapter 3, Functions, covers functional programming with Scala and how object- oriented and functional approaches complete each other. You'll identify generic classes and also identify how to create user-defined pattern matching and why is it useful.
Chapter 4, Scala Collections, teaches you how to work with lists. Then, it covers some more relevant data structures. Finally, you'll look at how collections relate to monads and how you can use that knowledge to make some powerful abstractions in your code.
Chapter 5, Scala Type System, covers the type system and polymorphism. It'll also enable you to identify the different types of variance, which provides a way to constrain parameterized types. Then, you'll cover some advanced types such as abstract type members and option.
Chapter 6, Implicits, covers implicit parameters and implicit conversions. You'll be learning about how they work, how to use them, and what kind of benefits and perils they provide.
Chapter 7, Functional Idioms, covers the core concepts of functional programming like Pure functions, immutability, and higher-order functions. It'll also cover two popular functional programming libraries called Cats and Doobie, and use them to write some interesting programs.
Chapter 8, Domain Specifc Languages, covers how Scala makes it possible to write powerful DSLs by providing a few interesting language features. Then, it'll cover a DSL that you'll very likely be using if you're going to work with Scala professionally.
Finally, you'll implement your own DSL.
What You Need for This Book
The minimum hardware requirements are as follows:
Please ensure you have the following software installed on your machine:
Mac
Linux
Installation and Setup
Before we start this book, we'll install IntelliJ IDE.
Installing IntelliJ IDE
Installing Scala plugin (make heading)
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Questions
If you have a problem with any aspect of this book, you can contact us at <[email protected]>, and we will do our best to address the problem.
Structure of a Scala Project
Let's look at our chatbot program in a complete runnable project. Let's navigate to the /day1-lesson1/1-project directory in our code supplement.
Note
The code is available on Github at the following link: https://github.com/TrainingByPackt/Professional-Scala
The preceding diagram is the typical directory structure of a Scala project. If you are familiar with the Java tools ecosystem, then you will notice the similarities between the maven project layout.
In src, we can see project sources ( main and test). target is a place where output artifacts are created, whereas project is used as a place to internally build the project. We will cover all of these concepts later on.
The head of any project is its build.sbt file. It consists of the following code:
The text inside it is a plain Scala snippet.
organization, name, and version are instances of sbt.key. For this point of view, := is a binary operator defined on keys. In Scala, any method with two arguments can be used with the syntax of a binary operator. := is a valid method name.
build.sbt is interpreted by the sbt tool.
Note
sbt – The original intention for the name, when sbt was created by Mark Harrah, was ' Simple Build Tool'. Later on, the author decided to avoid such a decipherment, and kept it as it was. You can read about the details of sbt here: https://www.scala-sbt.org/1.x/docs/index.html.
Basic sbt Commands
We will now talk about the basic sbt commands.
sbt compile should compile the project and live somewhere in its target compiled Java classes.
sbt run executes the main function of the project. Therefore, we can try to interact with our chatbot:
