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

The notion of function in F#


Let's begin with an intuitive definition of a function that many of us heard in school algebra class: function is a relationship that for each valid input yields a single consistent result. Such definition is a good enough to reflect both the commonality and the difference of functions and relations. In mathematics, a function is a relation, although not each relation is a function, as a relation may represent multiple results for the same single input. In the following figure, relation Rij on the left side is just fine for the representation of a function, as any item from set I maps to the one and only one item of set J. However, relation Rxy on the right side of the same figure cannot represent a function as at least one item of X exists, which maps to more than one item of Y, which is indicated by red mapping arrows.

Relations and functions

Another very important matter is the mapping consistency. Any function, when being repeatedly given the same input must...