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Learning Scala Programming

You're reading from   Learning Scala Programming Object-oriented programming meets functional reactive to create Scalable and Concurrent programs

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Product type Paperback
Published in Jan 2018
Publisher Packt
ISBN-13 9781788392822
Length 426 pages
Edition 1st Edition
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Author (1):
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 Sharma Sharma
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Sharma
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Table of Contents (21) Chapters Close

Title Page
Packt Upsell
Contributors
Preface
1. Getting Started with Scala Programming FREE CHAPTER 2. Building Blocks of Scala 3. Shaping our Scala Program 4. Giving Meaning to Programs with Functions 5. Getting Familiar with Scala Collections 6. Object-Oriented Scala Basics 7. Next Steps in Object-Oriented Scala 8. More on Functions 9. Using Powerful Functional Constructs 10. Advanced Functional Programming 11. Working with Implicits and Exceptions 12. Introduction to Akka 13. Concurrent Programming in Scala 14. Programming with Reactive Extensions 15. Testing in Scala 1. Other Books You May Enjoy Index

Another way around - generic classes and traits


We just saw the effect of genericity and it solved more than one problem, we wrote less code and achieved more. The serveMeal function was a generic one because it takes type parameters, in our case A and B. It performs the intended logic, great! Let's talk about parameterized types. You know the type List, right? Let's take a look at its declaration in the Scala standard library:

sealed abstract class List[+A] extends AbstractSeq[A] 
  with LinearSeq[A] 
  with Product 
  with GenericTraversableTemplate[A, List] 
  with LinearSeqOptimized[A, List[A]] 
  with Serializable 

Okay, the declaration seems far too complex, doesn't it? No, wait, we know what sealed means, we know why we used an abstract class, then the name List, and then a few more declarations for showing inheritance relationships. But there's this thing called [+A] in our declaration. Our job is to find out what this is and why we used it.

From the previous few topics, we gained an...

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