Practical OCaml

465 Pages·2007·5.97 MB·English

by  Joshua B. Smith (auth.)

Practical
OCamI
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Joshua B. Smith
Apress'
Practical OCamI
Copyright €) 2006 by Joshua B. Smith
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ISBN-13:978-1-59059-620-3
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Technical Reviewer: Richard Jones
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For Carol and Aaron
Contents at a Glance
About the Author xxi
About the Technical Reviewer xxlli
Acknowledgments xxv
ICHAPTER 1 Why Objective CamI (OCaml)? i
CHAPTER 2 Interacting with OCaml: The Toplevel 11
MJHAPTER 3 Syntax and Semantics 21
ICHAPTER 4 Understanding Functions 33
^CHAPTER 5 Practical: Creating a Simple Database 51
•CHAPTER 6 Primitive and Composite Types 6I
ICHAPTER 7 Practical: Simple Database Reports, Exports, and Imports 73
«)HAPTER 8 Collections 89
^CHAPTER 9 Files and File I/O 113
ICHAPTER 10 Exception Handling 123
ICHAPTER 11 Practical: A URI Library 135
ICHAPTER 12 Using Ocamldoc 145
MIHAPTER 13 Modules and Functors 155
CHAPTER 14 Practical: A Spam Filter 169
^CHAPTER 15 Practical: A Network-Aware Scoring Function 179
•CHAPTER 16 Ocamllex and Ocamlyacc 193
fCHAPTER 17 Practical: Complex Log File Parsing 213
ICHAPTER 18 The Objective Part of CamI 225
ICHAPTER 19 Digression: OCaml Is Not Pure 249
frCHAPTER 20 Digression: Functional Programming 26I
%H€ APTER 21 Practical: Web Programming 273
tCHAPTER 22 Practical: A Shoutcast Server 293
-CHAPTER 23 Using Threads 309
SCHAPTER 24 Practical: A Concurrent Web Crawler 329
KHAPTER 25 Interfacing with OCaml 349
iCHAPTER 26 Practical: Time and Logging Libraries 359
SHAPTER 27 Processing Binary Files 375
ffllHAPTER 28 OCamI Development Tools 40i
CHAPTER 29 Camlp4 411
9)HAPTER 30 Conclusion 431
aNDEX 445
Contents
About the Author xxi
About the Technical Reviewer xxiii
Acknowledgments xxv
CHAPTER 1 Why Objective CamI (OCamI)? 1
Who Benefits from Learning OCamI? 1
What Is OCamI Good For? 2
Who Uses OCamI? 3
Where Did OCamI Come From? 3
What Is the Current State of the Art? 4
Why This Book? 4
What Is Covered? 4
Interacting with OCamI: The Toplevel (Chapter 2) 4
Syntax and Semantics (Chapter 3) 5
Understanding Functions (Chapter 4) 5
Practical: Creating a Simple Database (Chapter 5) 5
Primitive and Composite Types (Chapter 6) 5
Practical: Simple Database Reports, Exports, and
Imports (Chapter 7) 5
Collections (Chapter 8) 5
Files and File I/O (Chapter 9) 5
Exception Handling (Chapter 10) 6
Practical: A URI Library (Chapter 11) 6
Using OCamldoc (Chapter 12) 6
Modules and Functors (Chapter 13) 6
Practical: A Spam Filter (Chapter 14) 6
Practical: A Network-Aware Scoring Function (Chapter 15) 6
Ocamllex and Ocamlyacc (Chapter 16) 6
Practical: Complex Log File Parsing (Chapter 17) 6
The Objective Part of CamI (Chapter 18) 7
Digression: OCamI Is Not Pure (Chapter 19) 7
Digression: Functional Programming (Chapter 20) 7
VII
CONTENTS
Practical: Web Programming (Chapter 21) 7
Practical: A Shoutcast Server (Chapter 22) 7
Using Threads (Chapter 23) 7
Practical: A Concurrent Web Crawler (Chapter 24) 7
Interfacing with OCamI (Chapter 25) 7
Practical: Time and Logging Libraries (Chapter 26) 8
Practical: Processing Binary Files (Chapter 27) 8
OCamI Development Tools (Chapter 28) 8
Camlp4 (Chapter 29) 8
Conclusion (Chapter 30) 8
What Isn't Covered? 8
What Are My Expectations for You? 8
Conclusion 9
•CHAPTER 2 Interacting with OCamI: The Toplevel 11
Distributions of OCamI 12
Official Distribution 12
Unofficial Releases 12
Installing OCamI 12
Windows 12
Linux 14
Interacting with the Toplevel 16
Hello World 17
Final Notes 18
Code Files 18
Basic Code Files 19
Custom Toplevel 20
Why Would You Do This? 20
How Do You Do This? 20
Conclusion 20
•JHAPTER 3 Syntax and Semantics 21
Variables in a Constant Language 21
What Variables Are Not 21
Let Bindings 22
Understanding Scope 23
KONTENTS
Records and Types 23
Creating Enums and Simple User-Defined Types 26
Defining Records 28
IVIore About Math 29
Integers and Floats 29
Others 29
Defining Functions 30
Imperative Programming 30
Recursion 30
Pattern Matching 31
Signatures 32
Conclusion 32
BHAPTER 4 Understanding Functions 33
Creating Values and Functions 33
Functions Must Have One Return Type 35
Constraining Types in Function Calls 35
Using Higher-Order Functions 36
Using Lists 37
Anonymous Functions 37
Why Use Anonymous Functions? 39
Understanding Consequences of Functions As Data 39
Curried Functions 41
Working with the Distance Type 41
Creating Recursive Functions 44
Why Do Recursive Functions Need a Special Designation? 45
Tail Recursion and Efficient Programming 45
Doing More Pattern Matching 46
Understanding the Default Match 47
Bindings Within Pattern Matches 47
Guarded Matches: A Return to the Distance Calculator 48
Understanding Built-in Functions 48
Using Labels and Optional Arguments 49
Conclusion 50
iCONTENTS
M;HAPTER 5 Practical: Creating a Simple Database 51
Two Modules You Need 51
Using the Hashtbl Module in OCamI 51
Using the Marshal Module 52
How to Use These Modules 52
Working with Files 52
Accounts Database 53
Some Sample Data 53
Important Functions for Handling Data 54
Manipulating the Database Contents 54
Saving and Loading the Database 56
Interacting with the Database 56
Quick Note About Code Length 59
Getting Price Information 59
Conclusion 60
CHAPTER 6 Primitive and Composite Types 61
Constant Type, Dynamic Data 62
Integers (Ints) 62
Floating-Point Numbers (Floats) 63
Strings and Chars 64
Using the Pervasives Module 66
Lists and Arrays 66
Exceptions 66
Other Types 67
Polymorphic Types 67
Composite Types 68
Polymorphic Variant Types 69
Conclusion 71
lOONTENTS
CHAPTER 7 Practical: Simple Database Reports, Exports,
and Imports 73
Format Codes 73
Printf 74
fprintf 75
eprintf 75
printf 75
sprintf 75
bprintf 76
kprintf 76
Scant 76
Scanning Module 76
fscanf 76
scant 77
sscant 77
bscant 77
kscant 77
Why Use These Functions? 77
Why Not Regular Expressions? 77
What About Line-Oriented I/O? 78
The Right Tool for the Right Job 78
More About Buffers 80
Writing a Report 80
Writing Export Functions 83
Writing Import Functions 84
Generating Data 86
Conclusion 87
CHAPTER 8 Collections 89
What Are Collections? 90
Comparison Functions 90
Lists 91
Arrays and Matrices 97
Hashtables 100
Queue 103
Stack 105