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

Events


We all use keyboards in our everyday work life. We use them to write code and compose e-mails. There is no knowing when a certain key will be pressed. However, when a key is pressed, the user expects certain action to happen—for example, the letter indicated by the key should appear in the editor when we are writing code.

This seems natural enough, doesn't it? However, note that there is an elaborate mechanism at work here. The operating system piece needs to know which key was pressed. So, one way to find this out is to go and ask periodically whether any key was pressed, and if so, which one. This is called "polling" for any interesting information. When we poll, we go and ask the driver, at intervals about any status regarding whether a key was pressed or not, as shown in the following figure:

Figure 10.4: Polling for key presses

This polling approach is problematic for the following reasons:

  • We really don't know whether the polling interval of a second is enough

  • In case someone is...