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

Chapter 9. More Data Crunching

Up until this point, all F# data transformation patterns covered were dealing with in-memory collections. That is, important data crunching use cases, such as querying data, already persisted within the enterprise, and ingesting data from outside of the enterprise have not been considered yet.

This chapter covers these data transformation scenarios and related coding patterns:

  • Querying the external data. I'll begin with querying the data using F# query expressions. We are going to see how the same transformation patterns we distilled in Chapter 8, Data Crunching - Data Transformation Patterns, in relation to core library function members are fully applicable to querying the external data presented in a data base or a web service. It also would be interesting to push the limits of composition in query expressions.

  • Parsing data from the external sources. We already spent a fair amount of time considering pattern matching amplified by active patterns. However, I...