book

Land of Lisp

Name: Land of Lisp
Author: Conrad Barski M.D.
ISBN: 9781593272814

by Conrad Barski M.D.

November 2010

Intermediate to advanced

504 pages

12h 45m

English

No Starch Press

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Land of Lisp
Acknowledgments
Introduction
What Makes Lisp So Cool and Unusual?
If Lisp Is So Great, Why Don't More People Use It?
Where Did Lisp Come From?
Where Does Lisp Get Its Power?
I. Lisp is Power
1. Getting Started with Lisp
Lisp DialectsA Tale of Two LispsUp-and-Coming LispsLisp Dialects Used for ScriptingANSI Common Lisp
Getting Started with CLISP
Installing CLISPStarting Up CLISP
What You've Learned

2. Creating Your First Lisp Program
The Guess-My-Number Game
Defining Global Variables in Lisp
Defining the small and big VariablesAn Alternative Global Variable Definition Function
Basic Lisp Etiquette
Defining Global Functions in Lisp
Defining the guess-my-number FunctionDefining the smaller and bigger FunctionsDefining the start-over Function
Defining Local Variables in Lisp
Defining Local Functions in Lisp
What You've Learned
3. Exploring the Syntax of Lisp Code
Syntax and Semantics
The Building Blocks of Lisp Syntax
SymbolsNumbersStrings
How Lisp Distinguishes Between Code and Data
Code ModeData Mode
Lists in Lisp
Cons CellsList FunctionsThe cons FunctionThe car and cdr FunctionsThe list FunctionNested Lists
What You've Learned
II. Lisp is Symmetry
4. Making Decisions with Conditions
The Symmetry of nil and ()Empty Equals FalseThe Four Disguises of ()
The Conditionals: if and Beyond
One Thing at a Time with ifGoing Beyond if: The when and unless AlternativesThe Command That Does It All: condBranching with case
Cool Tricks with Conditions
Using the Stealth Conditionals and and orUsing Functions That Return More than Just the Truth
Comparing Stuff: eq, equal, and More
What You've Learned
5. Building a Text Game Engine
The Wizard's Adventure GameOur Game WorldBasic Requirements
Describing the Scenery with an Association List
Describing the Location
Describing the Paths
How Quasiquoting WorksDescribing Multiple Paths at OnceFinding the Relevant EdgesConverting the Edges to DescriptionsJoining the Descriptions
Describing Objects at a Specific Location
Listing Visible ObjectsDescribing Visible Objects
Describing It All
Walking Around in Our World
Picking Up Objects
Checking Our Inventory
What You've Learned
6. Interacting with the World: Reading and Printing in Lisp
Printing and Reading TextPrinting to the ScreenSaying Hello to the UserStarting with print and readReading and Printing Stuff the Way Humans Like It
The Symmetry Between Code and Data in Lisp
Adding a Custom Interface to Our Game Engine
Setting Up a Custom REPLWriting a Custom read FunctionWriting a game-eval FunctionWriting a game-print Function
Trying Out Our Fancy New Game Interface
The Dangers of read and eval
What You've Learned
6.5. lambda: A Function So Important It Deserves Its Own Chapter
What lambda Does
Why lambda Is So Important
What You've Learned
7. Going Beyond Basic Lists
Exotic ListsDotted ListsPairsCircular ListsAssociation Lists
Coping with Complicated Data
Visualizing Tree-like DataVisualizing Graphs
Creating a Graph
Generating the DOT InformationConverting Node IdentifiersAdding Labels to Graph NodesGenerating the DOT Information for the NodesConverting Edges into DOT FormatGenerating All the DOT DataTurning the DOT File into a PictureUsing ThunksWriting to a FileCreating a StreamUnderstanding Keyword ParametersCapturing the Console OutputCreating a Picture of Our Graph
Creating Undirected Graphs
What You've Learned
8. This Ain't Your Daddy's Wumpus
The Grand Theft Wumpus Game
Defining the Edges of Congestion City
Generating Random EdgesLooping with the loop CommandPreventing IslandsBuilding the Final Edges for Congestion CityThe make-city-edges FunctionThe edges-to-alist FunctionThe add-cops Function
Building the Nodes for Congestion City
Initializing a New Game of Grand Theft Wumpus
Drawing a Map of Our City
Drawing a City from Partial KnowledgeKnown NodesKnown EdgesThe mapcan FunctionDrawing Only the Known Parts of the CityWalking Around Town
Let's Hunt Some Wumpus!
What You've Learned
9. Advanced Datatypes and Generic Programming
ArraysWorking with ArraysUsing a Generic SetterArrays vs. Lists
Hash Tables
Working with Hash TablesReturning Multiple ValuesHash Table PerformanceA Faster Grand Theft Wumpus Using Hash Tables
Common Lisp Structures
Working with StructuresWhen to Use Structures
Handling Data in a Generic Way
Working with SequencesSequence Functions for SearchingSequence Functions for Iterating Across a SequenceTwo More Important Sequence FunctionsCreating Your Own Generic Functions with Type Predicates
The Orc Battle Game
Global Variables for the Player and MonstersMain Game FunctionsPlayer Management FunctionsHelper Functions for Player AttacksMonster Management FunctionsThe MonstersThe Generic MonsterThe Wicked OrcThe Malicious HydraThe Slimy Slime MoldThe Cunning BrigandTo Battle!
What You've Learned
III. Lisp is Hacking
10. Looping with the loop Command
The loop MacroSome loop TricksCounting from a Starting Point to an Ending PointIterating Through Values in a Listdoing Stuff in a LoopDoing Stuff Under Certain ConditionsBreaking out of a Loop EarlyCollecting a List of ValuesUsing Multiple for ClausesEverything You Ever Wanted to Know About loop
Using loop to Evolve!
Growing Plants in Our WorldCreating AnimalsAnatomy of an AnimalHandling Animal MotionHandling Animal TurningHandling Animal EatingHandling Animal ReproductionSimulating a Day in Our WorldDrawing Our WorldCreating a User InterfaceLet's Watch Some Evolution!Explaining the Evolution
What You've Learned
11. Printing Text with the format Function
Anatomy of the format FunctionThe Destination ParameterThe Control String ParameterValue Parameters
Control Sequences for Printing Lisp Values
Control Sequences for Formatting Numbers
Control Sequences for Formatting IntegersControl Sequences for Formatting Floating-Point Numbers
Printing Multiple Lines of Output
Justifying Output
Iterating Through Lists Using Control Sequences
A Crazy Formatting Trick for Creating Pretty Tables of Data
Attack of the Robots!
What You've Learned
12. Working with Streams
Types of StreamsStreams by Type of ResourceStreams by DirectionOutput StreamsInput Streams
Working with Files
Working with Sockets
Socket AddressesSocket ConnectionsSending a Message over a SocketTidying Up After Ourselves
String Streams: The Oddball Type
Sending Streams to FunctionsWorking with Long StringsReading and Debugging
What You've Learned
13. Let's Create a Web Server!
Error Handling in Common LispSignaling a ConditionCreating Custom ConditionsIntercepting ConditionsProtecting Resources Against Unexpected Conditions
Writing a Web Server from Scratch
How a Web Server WorksRequest ParametersRequest Parameters for GET RequestsDecoding the Values of Request ParametersDecoding Lists of Request ParametersParsing the Request HeaderTesting get-header with a String StreamParsing the Request BodyOur Grand Finale: The serve Function!
Building a Dynamic Website
Testing the Request HandlerLaunching the Website
What You've Learned
13.5. Functional Programming Is Beautiful
IV. Lisp is Science
14. Ramping Lisp Up a Notch with Functional Programming
What Is Functional Programming?
Anatomy of a Program Written in the Functional Style
Higher-Order Programming
Code Composition with Imperative CodeUsing the Functional StyleHigher-Order Programming to the Rescue
Why Functional Programming Is Crazy
Why Functional Programming Is Fantastic
Functional Programming Reduces BugsFunctional Programs Are More CompactFunctional Code Is More Elegant
What You've Learned
15. Dice of Doom, a Game Written in the Functional Style
The Rules of Dice of Doom
A Sample Game of Dice of Doom
Implementing Dice of Doom, Version 1
Defining Some Global VariablesRepresenting the Game BoardDecoupling Dice of Doom's Rules from the Rest of the GameGenerating a Game TreeCalculating Passing MovesCalculating Attacking MovesFinding the NeighborsAttackingReinforcementsTrying Out Our New game-tree FunctionPlaying Dice of Doom Against Another HumanThe Main LoopGiving Information About the State of the GameHandling Input from Human PlayersDetermining the WinnerTrying Out the Human vs. Human Version of Dice of Doom
Creating an Intelligent Computer Opponent
The Minimax AlgorithmTurning Minimax into Actual CodeCreating a Game Loop with an AI PlayerPlaying Our First Human vs. Computer Game
Making Dice of Doom Faster
ClosuresMemoizationMemoizing the neighbors FunctionMemoizing the Game TreeMemoizing the rate-position FunctionTail Call OptimizationSupport for Tail Calls in Common LispTail Call Optimization in Dice of DoomA Sample Game on the 3-by-3 Board
What You've Learned
16. The Magic of Lisp Macros
A Simple Lisp MacroMacro ExpansionHow Macros Are TransformedUsing the Simple Macro
More Complex Macros
A Macro for Splitting ListsAvoiding Repeated Execution in MacrosAvoiding Variable CaptureA Recursion Macro
Macros: Dangers and Alternatives
What You've Learned
17. Domain-Specific Languages
What Is a Domain?
Writing SVG Files
Creating XML and HTML with the tag MacroWriting a Macro Helper FunctionCreating the tag MacroUsing the tag Macro to Generate HTMLCreating SVG-Specific Macros and FunctionsBuilding a More Complicated SVG Example
Creating Custom Game Commands for Wizard's Adventure Game
Creating New Game Commands by HandA Command for WeldingA Command for DunkingThe game-action MacroLet's Try the Completed Wizard's Adventure Game!
What You've Learned
18. Lazy Programming
Adding Lazy Evaluation to LispCreating the lazy and force CommandsCreating a Lazy Lists LibraryConverting Between Regular Lists and Lazy ListsMapping and Searching Across Lazy Lists
Dice of Doom, Version 2
Making Our AI Work on Larger Game Boards
Trimming the Game TreeApplying HeuristicsWinning by a Lot vs. Winning by a LittleAlpha Beta Pruning
What You've Learned
19. Creating a Graphical, Web-Based Version of Dice of Doom
Drawing the Game Board Using the SVG FormatDrawing a DieDrawing a TileDrawing the Board
Building the Web Server Interface
Writing Our Web Request HandlerLimitations of Our Game Web ServerInitializing a New GameAnnouncing a WinnerHandling the Human PlayerHandling the Computer PlayerDrawing the SVG Game Board from Within the HTML
Playing Version 3 of Dice of Doom
What You've Learned
20. Making Dice of Doom More Fun
Increasing the Number of Players
Rolling the Dice
Building Chance NodesDoing the Actual Dice RollingCalling the Dice Rolling Code from Our Game EngineUpdating the AI
Improving the Dice of Doom Reinforcement Rules
Conclusion
A. Epilogue
Functional Guild CruiserSynopsisHow It Kills BugsExplanationWeakness
Macro Guild Melee Fighters
SynopsisHow It Kills BugsExplanationWeakness
Restart Guild Armored Fighter
SynopsisHow It Kills BugsExplanationWeakness
Generic Setter Guild Supply Ship
SynopsisHow It Kills BugsExplanationWeakness
DSL Guild Hot Rods
SynopsisExplanationWeakness
CLOS Guild Battleship
SynopsisHow It Kills BugsExplanationExplanationWeakness
The Continuation Guild Rocket Pods
SynopsisHow It Kills BugsExplanationWeakness
Brevity Guild Micro Fighter
SynopsisHow It Kills BugsExplanationWeakness
Multicore Guild Formation Fighters
SynopsisHow It Fights BugsExplanationWeakness
The Lazy Guild Frigate
Lisp DialectSynopsisHow It Kills BugsExplanationWeakness
Index
About the Author
Updates

Content preview from Land of Lisp

Writing a Web Server from Scratch

Now that you have a basic understanding of sockets (covered in Chapter 12) and error handling, you know enough to make a web server that can serve dynamic web pages written in Lisp. After all, why should Apache (the world’s most popular web server) have all the fun?

How a Web Server Works

Hypertext Transfer Protocol, or HTTP, is the Internet protocol used for transferring web pages. It adds a layer on top of TCP/IP for requesting pages once a socket connection has been established. When a program running on a client computer (usually a web browser) sends a properly encoded request, the server will retrieve the requested page and send it over the socket stream in response.

Note

This web server is adapted from http.lisp ...

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