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Functional C#

Functional C#

By : Wisnu Anggoro
5 (3)
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Functional C#

Functional C#

5 (3)
By: Wisnu Anggoro

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 (12 chapters)
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Preface
Preface
What this book covers
What you need for this book
Who this book is for
Conventions
Reader feedback
Customer support
Free Chapter
1
1. Tasting Functional Style in C#
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1. Tasting Functional Style in C#
Introducing functional programming
Comparison between functional and imperative programming
Preparing the C# compiler
Concepts of functional programming
Feeling functional in C#
Transforming imperative code to functional code
The advantages and disadvantages of functional programming
Summary
2
2. Walkthrough Delegates
2. Walkthrough Delegates
Introducing delegates
Built-in delegates
Distinguishing variance in delegates
Summary
3
3. Expressing Anonymous Methods with Lambda Expressions
3. Expressing Anonymous Methods with Lambda Expressions
Getting to know anonymous methods
Lambda expressions
Subscribing for events using lambda expressions
The advantages of using lambda expression in functional programming
Summary
4
4. Extending Object Functionality with Extension Methods
4. Extending Object Functionality with Extension Methods
Getting closer to extension methods
Calling extension methods in the other assemblies
Leveraging the interface, collection, and object
Advantages of using extension methods in functional programming
Limitations of the extension method
Summary
5
5. Querying Any Collection Easily with LINQ
5. Querying Any Collection Easily with LINQ
Getting started with LINQ
Deferring LINQ execution
Choosing between fluent syntax and query expression syntax
Enumerating standard query operators
Summary
6
6. Enhancing the Responsiveness of the Functional Program with Asynchronous Programming
6. Enhancing the Responsiveness of the Functional Program with Asynchronous Programming
Building a responsive application
The asynchronous programming model pattern
The task-based asynchronous pattern
Asynchronous programming with the async and await keywords
Asynchronous functions in functional programming
Summary
7
7. Learning Recursion
7. Learning Recursion
Exploring recursion
Using tail recursion
Recursion in a functional approach using LINQ Aggregate
Summary
8
8. Optimizing the Code using Laziness and Caching Techniques
8. Optimizing the Code using Laziness and Caching Techniques
Introduction to laziness
Caching expensive resources
Summary
9
9. Working with Pattern
9. Working with Pattern
Dissecting pattern matching in functional programming
Introducing Monad as a design pattern
Summary
10
10. Taking an Action in C# Functional Programming
10. Taking an Action in C# Functional Programming
Developing functional programming in Windows forms
Summary
11
11. Coding Best Practice and Testing the Functional Code
11. Coding Best Practice and Testing the Functional Code
Coding best practices in functional C#
Separating the code from domain logic and mutable shell
Summary

The advantages and disadvantages of functional programming

So far, we have had to deal with functional programming by creating code using functional approach. Now, we can look at the advantages of the functional approach, such as the following:

  • The order of execution doesn't matter since it is handled by the system to compute the value we have given rather than the one defined by programmer. In other words, the declarative of the expressions will become unique. Because functional programs have an approach toward mathematical concepts, the system will be designed with the notation as close as possible to the mathematical way of concept.
  • Variables can be replaced by their value since the evaluation of expression can be done any time. The functional code is then more mathematically traceable because the program is allowed to be manipulated or transformed by substituting equals with equals. This feature is called referential transparency.
  • Immutability makes the functional code free of side effects. A shared variable, which is an example of a side effect, is a serious obstacle for creating parallel code and result in non-deterministic execution. By removing the side effect, we can have a good coding approach.
  • The power of lazy evaluation will make the program run faster because it only provides what we really required for the queries result. Suppose we have a large amount of data and want to filter it by a specific condition, such as showing only the data that contains the word Name. In imperative programming, we will have to evaluate each operation of all the data. The problem is that when the operation takes a long time, the program will need more time to run as well. Fortunately, the functional programming that applies LINQ will perform the filtering operation only when it is needed. That's why functional programming will save much of our time using lazy evaluation.
  • We have a solution for complex problems using composability. It is a rule principle that manages a problem by dividing it, and it gives pieces of the problem to several functions. The concept is similar to a situation when we organize an event and ask different people to take up a particular responsibility. By doing this, we can ensure that everything will done properly by each person.

Beside the advantages of functional programming, there are several disadvantages as well. Here are some of them:

  • Since there's no state and no update of variables is allowed, loss of performance will take place. The problem occurs when we deal with a large data structure and it needs to perform a duplication of any data even though it only changes a small part of the data.
  • Compared to imperative programming, much garbage will be generated in functional programming due to the concept of immutability, which needs more variables to handle specific assignments. Because we cannot control the garbage collection, the performance will decrease as well.
End of Section 8
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