The Book of F#: Breaking Free with Managed Functional Programming

Foreword....17

Preface....21

Acknowledgments....23

Introduction....25

Whom Is This Book For?....26

How Is This Book Organized?....26

Additional Resources....27

Chapter 1: Meet F#....29

F# in Visual Studio....30

Project Templates....30

Project Organization....32

Significance of Whitespace....33

Grouping Constructs....34

Namespaces....34

Modules....35

Expressions Are Everywhere....36

Application Entry Point....37

Implicit Return Values....37

Your First F# Program....38

Summary....40

Chapter 2: F# Interactive....41

Running F# Interactive....41

F# Interactive Output....43

The it Identifier....43

Playing in the Sandbox....43

#help....44

#quit....44

#load....44

#r....45

#I....45

#time....45

Scripting....46

F# Interactive Options....48

--load....48

--use....49

--reference....49

--lib....49

--define....49

--exec....50

--....50

--quiet....50

--optimize....51

--tailcalls....51

Summary....51

Chapter 3: Fundamentals....53

Immutability and Side Effects....54

Functional Purity....55

Bindings....56

let Bindings....56

use Bindings....58

do Bindings....61

Identifier Naming....61

Core Data Types....61

Boolean Values and Operators....62

Numeric Types....62

Characters....65

Strings....65

Type Inference....67

Nullability....69

Options....69

Unit Type....70

Enumerations....71

Flags Enumerations....71

Reconstructing Enumeration Values....73

Flow Control....73

Looping....73

Branching....75

Generics....76

Automatic Generalization....77

Explicit Generalization....78

Flexible Types....80

Wildcard Pattern....80

Statically Resolved Type Parameters....80

When Things Go Wrong....81

Handling Exceptions....81

Raising Exceptions....83

Custom Exceptions....84

String Formatting....86

Type Abbreviations....87

Comments....87

End-of-Line Comments....88

Block Comments....88

XML Documentation....88

Summary....90

Chapter 4: Staying Objective....91

Classes....92

Constructors....92

Fields....96

Properties....97

Methods....101

Events....105

Structures....108

Inheritance....109

Casting....110

Overriding Members....111

Abstract Classes....112

Abstract Members....113

Virtual Members....115

Sealed Classes....115

Static Members....116

Static Initializers....116

Static Fields....117

Static Properties....117

Static Methods....118

Mutually Recursive Types....119

Interfaces....119

Implementing Interfaces....120

Defining Interfaces....121

Custom Operators....122

Prefix Operators....122

Infix Operators....123

New Operators....124

Global Operators....124

Object Expressions....125

Type Extensions....127

Summary....128

Chapter 5: Let’s Get Functional....131

What Is Functional Programming?....132

Programming with Functions....132

Functions as Data....132

Interoperability Considerations....133

Currying....134

Partial Application....134

Pipelining....135

Function Composition....136

Recursive Functions....137

Tail-Call Recursion....138

Mutually Recursive Functions....139

Lambda Expressions....140

Closures....140

Functional Types....141

Tuples....141

Record Types....146

Discriminated Unions....150

Defining Discriminated Unions....151

Additional Members....157

Lazy Evaluation....158

Summary....160

Chapter 6: Going to Collections....161

Sequences....162

Creating Sequences....162

Working with Sequences....165

Arrays....170

Creating Arrays....170

Working with Arrays....172

Multidimensional Arrays....175

Jagged Arrays....176

Lists....177

Creating Lists....177

Working with Lists....178

Sets....180

Creating Sets....180

Working with Sets....181

Maps....183

Creating Maps....184

Working with Maps....184

Converting Between Collection Types....185

Summary....186

Chapter 7: Patterns, Patterns, Everywhere....187

Match Expressions....187

Guard Clauses....188

Pattern-Matching Functions....189

Exhaustive Matching....190

Variable Patterns....191

The Wildcard Pattern....191

Matching Constant Values....192

Identifier Patterns....192

Matching Union Cases....192

Matching Literals....193

Matching Nulls....193

Matching Tuples....194

Matching Records....195

Matching Collections....196

Array Patterns....196

List Patterns....196

Cons Patterns....197

Matching by Type....197

Type-Annotated Patterns....197

Dynamic Type-Test Patterns....198

As Patterns....199

Combining Patterns with And....199

Combining Patterns with OR....200

Parentheses in Patterns....200

Active Patterns....201

Partial Active Patterns....202

Parameterized Active Patterns....204

Summary....204

Chapter 8: Measuring Up....205

Defining Measures....206

Measure Formulas....206

Applying Measures....207

Stripping Measures....208

Enforcing Measures....209

Ranges....210

Converting Between Measures....210

Static Conversion Factors....210

Static Conversion Functions....211

Generic Measures....212

Custom Measure-Aware Types....212

Summary....213

Chapter 9: Can I Quote You on That?....215

Comparing Expression Trees and Quoted Expressions....216

Composing Quoted Expressions....218

Quoted Literals....218

.NET Reflection....219

Manual Composition....220

Splicing Quoted Expressions....222

Decomposing Quoted Expressions....222

Parsing Quoted Expressions....223

Substituting Reflection....225

Summary....227

Chapter 10: Show Me the Data....229

Query Expressions....229

Basic Querying....231

Filtering Data....232

Accessing Individual Items....235

Sorting Results....237

Grouping....238

Paginating....239

Aggregating Data....241

Detecting Items....242

Joining Multiple Data Sources....243

Extending Query Expressions....247

Type Providers....249

Available Type Providers....250

Using Type Providers....251

Example: Accessing an OData Service....252

Example: Parsing a String with RegexProvider....254

Summary....256

Chapter 11: Asynchronous and Parallel Programming....257

Task Parallel Library....258

Potential Parallelism....259

Data Parallelism....259

Task Parallelism....262

Asynchronous Workflows....269

Creating and Starting Asynchronous Workflows....270

Cancelling Asynchronous Workflows....273

Exception Handling....275

Asynchronous Workflows and the Task Parallel Library....276

Agent-Based Programming....278

Getting Started....278

Scanning for Messages....279

Replying to Messages....280

Example: Agent-Based Calculator....281

Summary....283

Chapter 12: Computation Expressions....285

Anatomy of a Computation Expression....286

Example: FizzBuzz....289

Example: Building Strings....292

Summary....297

Index....299

F# brings the power of functional-first programming to the .NET Framework, a platform for developing software in the Microsoft Windows ecosystem. If you're a traditional .NET developer used to C# and Visual Basic, discovering F# will be a revelation that will change how you code, and how you think about coding.

In The Book of F#, Microsoft MVP Dave Fancher shares his expertise and teaches you how to wield the power of F# to write succinct, reliable, and predictable code. As you learn to take advantage of features like default immutability, pipelining, type inference, and pattern matching, you'll be amazed at how efficient and elegant your code can be.

You'll also learn how to:

• Exploit F#'s functional nature using currying, partial application, and delegation
• Streamline type creation and safety with record types and discriminated unions
• Use collection types and modules to handle data sets more effectively
• Use pattern matching to decompose complex types and branch your code within a single expression
• Make your software more responsive with parallel programming and asynchronous workflows
• Harness object orientation to develop rich frameworks and interact with code written in other .NET languages
• Use query expressions and type providers to access and manipulate data sets from disparate sources

Break free of that old school of programming. The Book of F# will show you how to unleash the expressiveness of F# to create smarter, leaner code.