Book Image

Scala Functional Programming Patterns

By : Atul S. Khot
Book Image

Scala Functional Programming Patterns

By: Atul S. Khot

Overview of this book

Scala is used to construct elegant class hierarchies for maximum code reuse and extensibility and to implement their behavior using higher-order functions. Its functional programming (FP) features are a boon to help you design “easy to reason about” systems to control the growing software complexities. Knowing how and where to apply the many Scala techniques is challenging. Looking at Scala best practices in the context of what you already know helps you grasp these concepts quickly, and helps you see where and why to use them. This book begins with the rationale behind patterns to help you understand where and why each pattern is applied. You will discover what tail recursion brings to your table and will get an understanding of how to create solutions without mutations. We then explain the concept of memorization and infinite sequences for on-demand computation. Further, the book takes you through Scala’s stackable traits and dependency injection, a popular technique to produce loosely-coupled software systems. You will also explore how to currying favors to your code and how to simplify it by de-construction via pattern matching. We also show you how to do pipeline transformations using higher order functions such as the pipes and filters pattern. Then we guide you through the increasing importance of concurrent programming and the pitfalls of traditional code concurrency. Lastly, the book takes a paradigm shift to show you the different techniques that functional programming brings to your plate. This book is an invaluable source to help you understand and perform functional programming and solve common programming problems using Scala’s programming patterns.
Table of Contents (19 chapters)
Scala Functional Programming Patterns
Credits
About the Author
Aknowledgement
About the Reviewers
www.PacktPub.com
Preface
Index

Illusion and reality – the proxy pattern


Many of us have come across the term proxy server. At a large company, the Internet access is restricted by a proxy server. The company may provide access to work-related pages only. Social media sites may be blocked. The proxy server is the place where all these rules are built. It is a checkpoint. A proxy is a class, hiding the real thing. It essentially is an interface (not to confuse with Java interface) to an expensive object. The real object could possibly be a remote object.

The proxy pattern is used to implement cross-cutting concerns. A cross-cutting concern is:

  • A functionality needed across many different modules of an application

  • The functionality is not core to the application (it would be reused by another application too)

  • The functionality is necessary in most application (you need it very much—at times simply cannot do without it)

You don't want to reinvent the wheel and reimplement the functionality every time. Security, for example, is...