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

Deferring LINQ execution


LINQ implements a deferred execution concept when we query the data from a collection. This means that the query will not be executed in the constructor time but in the enumeration process instead. For example, we use the Where operator to query data from a collection. Actually, the query is not executed until we enumerate it. We can use the foreach operation to call the MoveNext command in order to enumerate the query. To discuss deferred execution in further detail, let's take a look at the following code, which we can find in the DeferredExecution.csproj project:

public partial class Program 
{ 
  public static void DeferredExecution() 
  { 
    List memberList = new List() 
    { 
      new Member 
      { 
        ID = 1, 
        Name = "Eddie Morgan", 
        Gender = "Male", 
        MemberSince = new DateTime(2016, 2, 10) 
      }, 
      new Member 
      { 
        ID = 2, 
...