Table of Contents

Learning F# Functional Data Structures and Algorithms

Credits

Foreword

Foreword

Foreword

About the Author

Acknowledgments

About the Reviewers

www.PacktPub.com

Support files, eBooks, discount offers, and more

Why subscribe?

Free access for Packt account holders

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the example code

Errata

Piracy

Questions

1. Embrace the Truth

Exploring the functional programming paradigm

Thinking functional – why functional programming matters

A historical primer of F#

The Hello World example

A brief F# language primer

Syntactical similarities and differences

Benefits of using F# over C#

Summary

2. Now Lazily Get Over It, Again

Setting up the IDE

Your first F# project

Talk is cheap, show me some code

To understand recursion, you must understand recursion

Memoization with Fibonacci

Towers of Hanoi

Sorting lazily

F# 4.0 – new features

Summary

3. What's in the Bag Anyway?

Exploring data structures in F#

Arrays

Lists

List comprehensions

Sequences

Tuples and records

Option types

Sets and maps

Discriminated unions

The active pattern

F# implementation of sorting algorithms

Algorithmic complexity and the Big-O notation

The bubble sort

Quicksort

The merge sort

Summary

4. Are We There Yet?

Diving deep into enumerations and sequences

Enumerating a CSV file

Query expressions

Creating sequences from collections

Usage considerations for sequences

Summary

5. Let's Stack Up

Let's build a stack

Stack with concurrency support

Testing the stack

Algorithm – parenthesis matching using stacks

Summary

6. See the Forest for the Trees

Tree as a data structure

The binary search tree

Navigating the tree

Abstract syntax trees

Summary

7. Jumping the Queue

Let's make a functional queue

The FSharpx.Collections library

The MailboxProcessor class in F#

Summary

8. Quick Boost with Graph

Graphs

Modeling graphs using F#

The shortest path algorithm

Finding the minimal path sum

Summary

9. Sets, Maps, and Vectors of Indirections

Sets and maps

Vectors

F# and the Intermediate Language

Summary

10. Where to Go Next?

References and further readings

F# language resources

Component design guidelines

Functional programming guides

F# for fun and profit

Data science with F#

Math and statistics programming with F#

Machine learning with F#

Books and interactive tutorials

Try F#

The F# programming wikibook

The F# workshop

The F# cheat sheet

Video tutorials

Community projects – development tools

Community projects – functional programming

Community projects – data science programming

Community projects – the GPU execution

General functional programming

Academic resources

Summary

Index

Learning F# Functional Data Structures and Algorithms

Learning F# Functional Data Structures and Algorithms

Copyright © 2015 Packt Publishing

All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.

Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author, nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book.

Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.

First published: June 2015

Production reference: 1240615

Published by Packt Publishing Ltd.

Livery Place

35 Livery Street

Birmingham B3 2PB, UK.

ISBN 978-1-78355-847-6

www.packtpub.com

Credits

Author

Adnan Masood, Ph.D.

Reviewers

Steve Bearman

Taha Hachana

Marcin Juraszek

Rohit Pathak

Commissioning Editor

Kunal Parikh

Acquisition Editor

Shaon Basu

Content Development Editor

Rahul Nair

Technical Editor

Parag Topre

Copy Editors

Relin Hedly

Sonia Mathur

Project Coordinator

Nidhi Joshi

Proofreaders

Stephen Copestake

Safis Editing

Indexer

Monica Ajmera Mehta

Graphics

Disha Haria

Jason Monteiro

Production Coordinator

Nilesh R. Mohite

Cover Work

Nilesh R. Mohite

Foreword

Functional programming is about to become mainstream, and learning F# helps a programmer build skills in multiple paradigms. It doesn't surprise me at all that Adnan has found his way to functional programming. His dedication to technological excellence is expressed eloquently in this book, and if you want to get started with F#, this is the book to read.

Jon Flanders

Pluralsight Trainer, Microsoft MVP

Foreword

In the era of multiprocessor and multimachine processing, functional principles are becoming increasingly important for modern programmers. For those developing in the Microsoft ecosystem, F# is a functional first multiparadigm language that allows practitioners to apply these principles in a truly powerful way. As developers become more familiar with functional data structures and the algorithms that use them truly safely, by extension, powerful software will become a more commonplace commodity that will drive the next era of technological innovation. I can't think of a more thorough and thoughtful person to help guide us through these principles than Adnan. Enjoy!

Seth Juarez

Senior Technical Evangelist, Microsoft

Foreword

F# is a functional and object-oriented programming language with the power of the .NET Framework. This language has gained huge popularity among a broad range of programmers. With a focus on writing simple code to solve complex problems, F# is being used by data scientists, enterprise developers, and enterprise enthusiasts. In fact, its popularity has increased so much in recent times that according to the TIOBE index (ranked 11th as of March 2015), F# is all set to gain an esteemed position among the top 10 programming languages.

With the rise in interest and usage around F#, it's bound to continue to attract the attention of hobbyists who want to try out writing programs with F#. I am very excited about Adnan Masood's efforts and appreciative of his work, which focuses on the basics of functional programming, data structures, and algorithms. Adnan has followed a very structured approach to take you on a journey where you can discover and familiarize yourself with this powerful multiparadigm programming language. Starting with setting the context and discussing the basics of F# programming, Adnan gradually moves on to a more detailed and increasingly focused conversation surrounding data structures and algorithms. He also covers approaches related to testing bespoke data structures and algorithms. Towards the end, Adnan covers the implementation of modern and complex abstract data types (ADTs) and highlights how to use parallel programming and asynchrony within the F# setting.

I highly recommend this book and ask you to focus your energies on learning this amazing and powerful multiparadigm, open source, and cross-platform programming language. This book will help you tackle computing problems with a simple, maintainable, and robust code.

Happy F# Programming.

Hammad Rajjoub

Architect Advisor, Mobility Lead (Asia), Microsoft

About the Author

Adnan Masood, Ph.D. is a developer, software architect, and researcher and specializes in machine learning and Bayesian belief networks. He is an avid engineer and is most comfortable working with the IDE. Before joining Green Dot Corporation, a leading prepaid financial technology institution, he enjoyed life as a principal engineer of a start-up and worked for a leading UK nonprofit organization as a solutions architect.

A strong believer in the development community, Adnan is an active member of the Open Web Application Security Project (OWASP), an organization dedicated to software security. In the .NET community, he is a cofounder and president of the Pasadena .NET Developers group, which he has been successfully leading for 8 years. He pursues interests in algorithmic puzzles, machine learning, functional programming, cloud computing, service-oriented architecture (SOA), .NET, design patterns, application security, and robotics. He has also led a number of successful enterprise solutions and consulted for several Fortune 500 company projects.

Adnan devotes himself to his own continual, practical education. He holds certifications in big data, machine learning, and systems architecture from Massachusetts Institute of Technology; an Application Security certification from Stanford University; an SOA Smarts certification from Carnegie Mellon University; and certifications as a ScrumMaster, Microsoft Certified Trainer, Microsoft Certified Solutions Developer, and Sun Certified Java Developer.

Adnan has taught Windows Communication Foundation (WCF) courses at the University of California, San Diego, and loves to conduct presentations at top academic and technology conferences (for example, IEEE-HST, IASA, and DevConnections), local code camps, and user groups. He is also a volunteer FLL robotics coach for middle school students at Universal Academy of Florida.

At home, his two very energetic boys, Zakariya and Ali, keep him busy—but not quite busy enough to keep him from compulsively buying (though not always reading) books in all formats. Adnan defines Pluto as a planet, chocolate as a food group, and A Game of Thrones as historical fiction.

For more details, visit Adnan's blog (http://blog.adnanmasood.com), GitHub repository (http://github.com/adnanmasood), and Twitter (@adnanmasood). Adnan can be reached at .

Acknowledgments

I am very grateful to the technical reviewers—Steve Bearman, Taha Hachana, Marcin Juraszek, and Rohit Pathak—whose meticulous reviews proved invaluable in improving the quality of this book. Thank you for your diligence and your help throughout the process. Thanks to the excellent team at Packt Publishing. I would also like to thank the technical editor, Parag Topre, and the content development editor, Rahul Nair, who worked with me and kept this project on track to publish this book. Your assistance as an editor and reviewer along with your comments were invaluable in ensuring that this book was a comprehensive and reliable source of information on F# and functional programming.

Thanks to Don Syme and Microsoft Research, without whom neither F# nor this book would have been possible, and to the excellent F# community that provides plenty of resources. It has been my privilege to work closely with Jeff Bergman (Google), who got me started on F# and functional programming. I am forever grateful to Stephen Soong, for his unwavering support and feedback, and David Lazar, who allowed me to run seemingly crazy ideas by him. I am indebted to all my friends and colleagues, including Nicolas Naaman, David Gullett, Calvin Park, Teresa Watkins, Raja Peer, Dave Banta, Ajit Kumar, Dr. Jevdet Rexhepi, Paul Watson, Dr. John Dean, Kamran Masood, Jim Java, Muhammad Mansoor, Antony Chhan, Rashid Kamran, Jeff Cox, Mobeen Minai, Rob Walling, and Kamran Zameer, to name a few, for reading the early drafts and providing feedback and encouragement. And last but not least, special thanks to my family for their support and to my kids, Zakariya and Ali; without their shenanigans, this book would have been finished 6 months earlier. Love you guys!

About the Reviewers

Steve Bearman is a software developer with his own software and consulting company, Suzy B Studios. He supports all sectors from science and engineering through business and finance and specializes in the thorny, complex problems where architecture, algorithms, performance, and usability are critical. He has been developing with .NET for over a decade. He has long been functionally oriented; one of his first preferred programming languages, years ago, was the early functional, mathematical programming language APL.

Steve has a special fondness for good algorithms and appropriate technology. He has taught university graduate-level computer science and managed marketing and operations as the VP of a manufacturing corporation. Steve has published technical papers dealing with data, its analysis, interpretation, and automated collection. He speaks frequently on technical topics. He has an SB in Mathematics from MIT and an MA in applied mathematics, concentrating on algorithms and mathematical statistics, from the University of California, San Diego.

He enjoys life with his beautiful wife and two dogs, holds black belts in two styles of martial arts, juggles, rides his unicycle, and enjoys the arts and the outdoors.

Taha Hachana is an enthusiast F# hacker. He has been using this language since 2008 (2 years before it became a Microsoft product). As an active community member, he has been maintaining several open source F# projects on GitHub, focusing on web development with the WebSharper framework and data visualization. When he's not coding, Taha enjoys practicing martial arts and yoga. You can follow him on Twitter at @TahaHachana and read his blog at http://fsharp-code.blogspot.com/.

Marcin Juraszek is a software engineer at Microsoft. He is associated with Office Online, a web browser-based version of the Microsoft Office productivity suite.

He holds bachelor's of engineering and master's of science degrees in computer science from the Silesian University of Technology in Gliwice, Poland. Before moving to the U.S., Marcin worked at Future Processing, one of the fastest growing software companies in central and eastern Europe.

He has been a .NET developer since the last 4 years. His expertise spans across most of .NET stack, including C#, VB.NET, F#, ASP.NET, XAML, WPF, Silverlight, LINQ, and .NET Core. He's also interested in new technologies, such as TypeScript, Azure, Roslyn, and so on.

He runs his own programming-oriented blog at http://marcinjuraszek.com and is an active member of the Stack Overflow community.

Rohit Pathak has a degree in computer science from Rajiv Gandhi Technical University. He picked up his interest in functional programming while working on High Performance Computing (HPC) at AITR (Acropolis Institute of Technology and Research). For years, he worked at Innovation at Incubation Labs and NTI (NEC Technologies India Limited), focusing on machine learning, static model checking, compilers, and HPC. Currently, he is working as a lead software engineer with the system and verification group at Cadence Design Systems.

www.PacktPub.com

Support files, eBooks, discount offers, and more

For support files and downloads related to your book, please visit www.PacktPub.com.

Did you know that Packt offers eBook versions of every book published, with PDF and ePub files available? You can upgrade to the eBook version at www.PacktPub.com and as a print book customer, you are entitled to a discount on the eBook copy. Get in touch with us at for more details.

At www.PacktPub.com, you can also read a collection of free technical articles, sign up for a range of free newsletters and receive exclusive discounts and offers on Packt books and eBooks.

https://www2.packtpub.com/books/subscription/packtlib

Do you need instant solutions to your IT questions? PacktLib is Packt's online digital book library. Here, you can search, access, and read Packt's entire library of books.

Why subscribe?

Fully searchable across every book published by Packt

Copy and paste, print, and bookmark content

On demand and accessible via a web browser

Free access for Packt account holders

If you have an account with Packt at www.PacktPub.com, you can use this to access PacktLib today and view 9 entirely free books. Simply use your login credentials for immediate access.

Preface