Book Image

F# 4.0 Design Patterns

By : Gene Belitski
Book Image

F# 4.0 Design Patterns

By: Gene Belitski

Overview of this book

Following design patterns is a well-known approach to writing better programs that captures and reuses high-level abstractions that are common in many applications. This book will encourage you to develop an idiomatic F# coding skillset by fully embracing the functional-first F# paradigm. It will also help you harness this powerful instrument to write succinct, bug-free, and cross-platform code. F# 4.0 Design Patterns will start off by helping you develop a functional way of thinking. We will show you how beneficial the functional-first paradigm is and how to use it to get the optimum results. The book will help you acquire the practical knowledge of the main functional design patterns, the relationship of which with the traditional Gang of Four set is not straightforward. We will take you through pattern matching, immutable data types, and sequences in F#. We will also uncover advanced functional patterns, look at polymorphic functions, typical data crunching techniques, adjusting code through augmentation, and generalization. Lastly, we will take a look at the advanced techniques to equip you with everything you need to write flawless code.
Table of Contents (20 chapters)
F# 4.0 Design Patterns
Credits
About the Author
Acknowledgements
About the Reviewer
www.PacktPub.com
Preface

Sum algebraic data types


In contrast to the product algebraic data types covered earlier, sum algebraic data types use the set sum operation for the composition of new types. The easiest case for this type is an enumeration composed of just a bunch of individual values. A more generic case is a type that groups a bunch of different types called variants. Each variant contributes a set of its possible values, which are created with the help of the variant constructor. All possible values of all variants combined with a set sum (union) constitute the sum type.

Another contrast with product types is that of all possible variants, only a single one can be a value for an instance of the sum type, while all fields constitute the value of a product type.

This may sound complicated, but the concept is quite simple. Let's dive in.

Discriminated unions

Sum algebraic data types were introduced in F# by the native data type named discriminated union (DU). The utter flexibility of discriminated unions makes...