Book Image

Learning Scala Programming

By : Vikash Sharma
Book Image

Learning Scala Programming

By: Vikash Sharma

Overview of this book

Scala is a general-purpose programming language that supports both functional and object-oriented programming paradigms. Due to its concise design and versatility, Scala's applications have been extended to a wide variety of fields such as data science and cluster computing. You will learn to write highly scalable, concurrent, and testable programs to meet everyday software requirements. We will begin by understanding the language basics, syntax, core data types, literals, variables, and more. From here you will be introduced to data structures with Scala and you will learn to work with higher-order functions. Scala's powerful collections framework will help you get the best out of immutable data structures and utilize them effectively. You will then be introduced to concepts such as pattern matching, case classes, and functional programming features. From here, you will learn to work with Scala's object-oriented features. Going forward, you will learn about asynchronous and reactive programming with Scala, where you will be introduced to the Akka framework. Finally, you will learn the interoperability of Scala and Java. After reading this book, you'll be well versed with this language and its features, and you will be able to write scalable, concurrent, and reactive programs in Scala.
Table of Contents (21 chapters)
Title Page
Packt Upsell
Contributors
Preface
Index

Implicit parameters


We use implicit parameters when we want the compiler to help us find a value that's already available for a certain type. We've just seen an example of an implicit parameter when we talked about Future. Why don't we define something similar for ourselves?

We can think of a scenario where we need to show the present date in our application and we want to avoid passing a date's instance explicitly again and again. Instead, we can make the LocalDateTime.now value implicit to the respective functions and let the current date and time be passed as an implicit parameter to them. Let's write some code for this:

import java.time.{LocalDateTime} 
 
object ImplicitParameter extends App { 
 
  implicit val dateNow = LocalDateTime.now() 
 
  def showDateTime(implicit date: LocalDateTime) = println(date) 
   
  //Calling functions! 
  showDateTime 
} 

The following is the result:

2017-11-17T10:06:12.321 

Think of the showDateTime function as the one that needs the date-time's current value...