F# Programming

Preface....7

What is Wikibooks?....7

What is this book?....7

Who are the authors?....7

Wikibooks in Class....7

Happy Reading!....8

Introduction....8

Introducing F#....8

A Brief History of F#....8

Why Learn F#?....8

References....9

F# Basics....10

Getting Set Up....10

Windows....10

Mac OSX, Linux and UNIX....11

Basic Concepts....11

Major Features....11

Functional Programming Contrasted with Imperative Programming....13

Structure of F# Programs....14

Working With Functions....16

Declaring Values and Functions....16

Declaring Variables....16

Declaring Functions....16

Pattern Matching Basics....19

Pattern Matching Syntax....19

Alternative Pattern Matching Syntax....20

Binding Variables with Pattern Matching....20

Pay Attention to F# Warnings....20

Recursion and Recursive Functions....21

Examples....21

Tail Recursion....22

Exercises....23

Additional Reading....23

Higher Order Functions....23

Familiar Higher Order Functions....23

The |> Operator....24

Anonymous Functions....25

Currying and Partial Functions....25

Immutable Data Structures....27

Option Types....27

Using Option Types....27

Pattern Matching Option Types....27

Other Functions in the Option Module....27

Tuples and Records....28

Defining Tuples....28

Defining Records....29

Lists....30

Creating Lists....30

Pattern Matching Lists....31

Using the List Module....32

Exercises....34

Sequences....35

Defining Sequences....35

Iterating Through Sequences Manually....36

The Seq Module....36

Sets and Maps....37

Sets....37

Maps....39

Set and Map Performance....40

Discriminated Unions....40

Creating Discriminated Unions....40

Union basics: an On/Off switch....40

Holding Data In Unions: a dimmer switch....40

Creating Trees....41

Generalizing Unions For All Datatypes....41

Examples....41

Additional Reading....42

Imperative Programming....43

Mutable Data....43

mutable Keyword....43

Ref cells....43

Encapsulating Mutable State....44

Control Flow....44

Imperative Programming in a Nutshell....44

if/then Decisions....45

for Loops Over Ranges....45

for Loops Over Collections and Sequences....45

while Loops....46

Arrays....46

Creating Arrays....46

Working With Arrays....46

Differences Between Arrays and Lists....49

Mutable Collections....50

List<'T> Class....50

LinkedList<'T> Class....50

HashSet<'T>, and Dictionary<'TKey, 'TValue> Classes....51

Differences Between .NET BCL and F# Collections....52

Basic I/O....52

Working with the Console....52

System.IO Namespace....53

Exception Handling....54

Try/With....54

Raising Exceptions....54

Try/Finally....54

Defining New Exceptions....55

Exception Handling Constructs....55

Object Oriented Programming....56

Operator Overloading....56

Using Operators....56

Operator Overloading....56

Defining New Operators....56

Classes....57

Defining an Object....57

Class Members....59

Generic classes....61

Pattern Matching Objects....61

Inheritance....62

Subclasses....62

Working With Subclasses....63

Interfaces....64

Defining Interfaces....64

Using Interfaces....64

Examples....66

Events....67

Defining Events....67

Adding Callbacks to Event Handlers....68

Working with EventHandlers Explicitly....68

Passing State To Callbacks....69

Retrieving State from Callers....70

Using the Event Module....71

Modules and Namespaces....72

Defining Modules....72

Defining Namespaces....73

F# Advanced....76

Units of Measure....76

Use Cases....76

Defining Units....77

Dimensionless Values....77

Generalizing Units of Measure....77

F# PowerPack....78

External Resources....78

Caching....78

Partial Functions....78

Memoization....78

Lazy Values....79

Active Patterns....79

Defining Active Patterns....79

Additional Resources....81

Advanced Data Structures....81

Stacks....81

Queues....82

Binary Search Trees....83

Lazy Data Structures....86

Additional Resources....87

Reflection....87

Inspecting Types....87

Microsoft.FSharp.Reflection Namespace....88

Working With Attributes....89

Computation Expressions....90

Monad Primer....90

Defining Computation Expressions....91

What are Computation Expressions Used For?....92

Additional Resources....92

Multi-threaded and Concurrent Applications....93

Async Workflows....93

Defining Async Workflows....93

Async Extensions Methods....94

Async Examples....94

Concurrency with Functional Programming....95

MailboxProcessor Class....96

Defining MailboxProcessors....96

MailboxProcessor Methods....97

Two-way Communication....97

MailboxProcessor Examples....97

F# Tools....99

Lexing and Parsing....99

Lexing and Parsing from a High-Level View....99

Extended Example: Parsing SQL....99

Text and image sources, contributors, and licenses....104

Text....104

Images....105

Content license....105

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