Book Image

Functional C#

Book Image

Functional C#

Overview of this book

Functional programming makes your application faster, improves performance, and increases your productivity. C# code is written at a higher level of abstraction, so that code will be closer to business requirements, abstracting away many low-level implementation details. This book bridges the language gap for C# developers by showing you how to create and consume functional constructs in C#. We also bridge the domain gap by showing how functional constructs can be applied in business scenarios. We’ll take you through lambda expressions and extension methods, and help you develop a deep understanding of the concepts and practices of LINQ and recursion in C#. By the end of the book, you will be able to write code using the best approach and will be able to perform unit testing in functional programming, changing how you write your applications and revolutionizing your projects.
Table of Contents (19 chapters)
Functional C#
Credits
About the Author
Acknowledgments
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Asynchronous functions in functional programming


Now, using the chaining method, we are going to use the async and await keywords in functional programming. Suppose we have three tasks, as shown in the following code snippet, and we need to chain them together:

public async static Task<int> FunctionA( 
  int a) => await Task.FromResult(a * 1); 
public async static Task<int> FunctionB( 
  int b) => await Task.FromResult(b * 2); 
public async static Task<int> FunctionC( 
  int c) => await Task.FromResult(c * 3); 

For that purpose, we have to create a new extension method for Task<T> named MapAsync, with the following implementation:

public static class ExtensionMethod 
{ 
  public static async Task<TResult> MapAsync<TSource, TResult>( 
    this Task<TSource> @this, 
    Func<TSource, Task<TResult>> fn) => await fn(await @this); 
} 

The MapAsync() method allows us to define...