Sign In Start Free Trial
Account

Add to playlist

Create a Playlist

Modal Close icon
You need to login to use this feature.
  • Scala Programming Projects
  • Toc
  • feedback
Scala Programming Projects

Scala Programming Projects

By : Valot, Nicolas Jorand
3.8 (5)
close
Scala Programming Projects

Scala Programming Projects

3.8 (5)
By: 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 (13 chapters)
close

Covariance and contravariance

When an F type accepts a type parameter of A, we can add a + or - sign in front of the parameter declaration to indicate the variance of F on A:

  • F[+A] makes F covariant on A. This means that if B <:< A (where B extends A), then F[B] <:< F[A].
  • F[-A] makes F contravariant on A. If B <:< A, then F[A]  <:< F[B].
  • F[A] makes F invariant on A. If B <:< A, then there is no relationship between F[A] and F[B].

InvariantDecoder

We are now going to explore this variance concept with an example. Let's start with a simple class hierarchy, as shown in the following code:

trait Animal
case class Cat(name: String) extends Animal
case class Dog(name...
bookmark search playlist download font-size

Change the font size

margin-width

Change margin width

day-mode

Change background colour

Close icon Search
Country selected

Close icon Your notes and bookmarks

Delete Bookmark

Modal Close icon
Are you sure you want to delete it?
Cancel
Yes, Delete