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Mastering Functional Programming

You're reading from   Mastering Functional Programming Functional techniques for sequential and parallel programming with Scala

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Product type Paperback
Published in Aug 2018
Publisher Packt
ISBN-13 9781788620796
Length 380 pages
Edition 1st Edition
Languages
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Author (1):
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Anatolii Kmetiuk Anatolii Kmetiuk
Author Profile Icon Anatolii Kmetiuk
Anatolii Kmetiuk
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Table of Contents (17) Chapters Close

Preface 1. The Declarative Programming Style FREE CHAPTER 2. Functions and Lambdas 3. Functional Data Structures 4. The Problem of Side Effects 5. Effect Types - Abstracting Away Side Effects 6. Effect Types in Practice 7. The Idea of the Type Classes 8. Basic Type Classes and Their Usage 9. Libraries for Pure Functional Programming 10. Patterns of Advanced Functional Programming 11. Introduction to the Actor Model 12. The Actor Model in Practice 13. Use Case - A Parallel Web Crawler 14. Introduction to Scala 15. Assessments 16. Other Books You May Enjoy

Higher-order functions

Another important concept that appears in functional programming is that of higher-order functions. A higher-order function is a function that accepts a function as an argument. A very trivial example of where this may be useful is control structures. For example, a while loop can be expressed in a functional way as a higher-order function that accepts the body of the loop and a predicate as an argument.

The body of the loop can be expressed as a function that does not accept any arguments, but computes some side effects. The way it works is that we have a function accept a 0-argument function and a predicate, and we call the same loop function recursively while the predicate is true.

We can call the new control structure whileDiy, and it can be defined as follows:

@annotation.tailrec
def whileDiy(predicate: => Boolean)(body: => Unit): Unit =
if ...
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