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The Racket Guide
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The Racket Guide

Matthew Flatt,
Robert Bruce Findler,
and PLT

This guide is intended for programmers who are new to Racket or new to some part of Racket. It assumes programming experience, so if you are new to programming, consider instead reading How to Design Programs. If you want an especially quick introduction to Racket, start with Quick: An Introduction to Racket with Pictures.

Chapter 2 provides a brief introduction to Racket. From Chapter 3 on, this guide dives into details—covering much of the Racket toolbox, but leaving precise details to The Racket Reference and other reference manuals.

The source of this manual is available on GitHub.

    1 Welcome to Racket

      1.1 Interacting with Racket

      1.2 Definitions and Interactions

      1.3 Creating Executables

      1.4 A Note to Readers with Lisp/Scheme Experience

    2 Racket Essentials

      2.1 Simple Values

      2.2 Simple Definitions and Expressions

        2.2.1 Definitions

        2.2.2 An Aside on Indenting Code

        2.2.3 Identifiers

        2.2.4 Function Calls (Procedure Applications)

        2.2.5 Conditionals with if, and, or, and cond

        2.2.6 Function Calls, Again

        2.2.7 Anonymous Functions with lambda

        2.2.8 Local Binding with define, let, and let*

      2.3 Lists, Iteration, and Recursion

        2.3.1 Predefined List Loops

        2.3.2 List Iteration from Scratch

        2.3.3 Tail Recursion

        2.3.4 Recursion versus Iteration

      2.4 Pairs, Lists, and Racket Syntax

        2.4.1 Quoting Pairs and Symbols with quote

        2.4.2 Abbreviating quote with '

        2.4.3 Lists and Racket Syntax

    3 Built-In Datatypes

      3.1 Booleans

      3.2 Numbers

      3.3 Characters

      3.4 Strings (Unicode)

      3.5 Bytes and Byte Strings

      3.6 Symbols

      3.7 Keywords

      3.8 Pairs and Lists

      3.9 Vectors

      3.10 Hash Tables

      3.11 Boxes

      3.12 Void and Undefined

    4 Expressions and Definitions

      4.1 Notation

      4.2 Identifiers and Binding

      4.3 Function Calls (Procedure Applications)

        4.3.1 Evaluation Order and Arity

        4.3.2 Keyword Arguments

        4.3.3 The apply Function

      4.4 Functions (Procedures): lambda

        4.4.1 Declaring a Rest Argument

        4.4.2 Declaring Optional Arguments

        4.4.3 Declaring Keyword Arguments

        4.4.4 Arity-Sensitive Functions: case-lambda

      4.5 Definitions: define

        4.5.1 Function Shorthand

        4.5.2 Curried Function Shorthand

        4.5.3 Multiple Values and define-values

        4.5.4 Internal Definitions

      4.6 Local Binding

        4.6.1 Parallel Binding: let

        4.6.2 Sequential Binding: let*

        4.6.3 Recursive Binding: letrec

        4.6.4 Named let

        4.6.5 Multiple Values: let-values, let*-values, letrec-values

      4.7 Conditionals

        4.7.1 Simple Branching: if

        4.7.2 Combining Tests: and and or

        4.7.3 Chaining Tests: cond

      4.8 Sequencing

        4.8.1 Effects Before: begin

        4.8.2 Effects After: begin0

        4.8.3 Effects If...: when and unless

      4.9 Assignment: set!

        4.9.1 Guidelines for Using Assignment

        4.9.2 Multiple Values: set!-values

      4.10 Quoting: quote and '

      4.11 Quasiquoting: quasiquote and

      4.12 Simple Dispatch: case

      4.13 Dynamic Binding: parameterize

    5 Programmer-Defined Datatypes

      5.1 Simple Structure Types: struct

      5.2 Copying and Update

      5.3 Structure Subtypes

      5.4 Opaque versus Transparent Structure Types

      5.5 Structure Comparisons

      5.6 Structure Type Generativity

      5.7 Prefab Structure Types

      5.8 More Structure Type Options

    6 Modules

      6.1 Module Basics

        6.1.1 Organizing Modules

        6.1.2 Library Collections

        6.1.3 Packages and Collections

        6.1.4 Adding Collections

      6.2 Module Syntax

        6.2.1 The module Form

        6.2.2 The #lang Shorthand

        6.2.3 Submodules

        6.2.4 Main and Test Submodules

      6.3 Module Paths

      6.4 Imports: require

      6.5 Exports: provide

      6.6 Assignment and Redefinition

      6.7 Modules and Macros

    7 Contracts

      7.1 Contracts and Boundaries

        7.1.1 Contract Violations

        7.1.2 Experimenting with Contracts and Modules

        7.1.3 Experimenting with Nested Contract Boundaries

      7.2 Simple Contracts on Functions

        7.2.1 Styles of ->

        7.2.2 Using define/contract and ->

        7.2.3 any and any/c

        7.2.4 Rolling Your Own Contracts

        7.2.5 Contracts on Higher-order Functions

        7.2.6 Contract Messages with “???”

        7.2.7 Dissecting a contract error message

      7.3 Contracts on Functions in General

        7.3.1 Optional Arguments

        7.3.2 Rest Arguments

        7.3.3 Keyword Arguments

        7.3.4 Optional Keyword Arguments

        7.3.5 Contracts for case-lambda

        7.3.6 Argument and Result Dependencies

        7.3.7 Checking State Changes

        7.3.8 Multiple Result Values

        7.3.9 Fixed but Statically Unknown Arities

      7.4 Contracts: A Thorough Example

      7.5 Contracts on Structures

        7.5.1 Guarantees for a Specific Value

        7.5.2 Guarantees for All Values

        7.5.3 Checking Properties of Data Structures

      7.6 Abstract Contracts using #:exists and #:∃

      7.7 Additional Examples

        7.7.1 A Customer-Manager Component

        7.7.2 A Parameteric (Simple) Stack

        7.7.3 A Dictionary

        7.7.4 A Queue

      7.8 Building New Contracts

        7.8.1 Contract Struct Properties

        7.8.2 With all the Bells and Whistles

      7.9 Gotchas

        7.9.1 Contracts and eq?

        7.9.2 Contract boundaries and define/contract

        7.9.3 Exists Contracts and Predicates

        7.9.4 Defining Recursive Contracts

        7.9.5 Mixing set! and contract-out

    8 Input and Output

      8.1 Varieties of Ports

      8.2 Default Ports

      8.3 Reading and Writing Racket Data

      8.4 Datatypes and Serialization

      8.5 Bytes, Characters, and Encodings

      8.6 I/O Patterns

    9 Regular Expressions

      9.1 Writing Regexp Patterns

      9.2 Matching Regexp Patterns

      9.3 Basic Assertions

      9.4 Characters and Character Classes

        9.4.1 Some Frequently Used Character Classes

        9.4.2 POSIX character classes

      9.5 Quantifiers

      9.6 Clusters

        9.6.1 Backreferences

        9.6.2 Non-capturing Clusters

        9.6.3 Cloisters

      9.7 Alternation

      9.8 Backtracking

      9.9 Looking Ahead and Behind

        9.9.1 Lookahead

        9.9.2 Lookbehind

      9.10 An Extended Example

    10 Exceptions and Control

      10.1 Exceptions

      10.2 Prompts and Aborts

      10.3 Continuations

    11 Iterations and Comprehensions

      11.1 Sequence Constructors

      11.2 for and for*

      11.3 for/list and for*/list

      11.4 for/vector and for*/vector

      11.5 for/and and for/or

      11.6 for/first and for/last

      11.7 for/fold and for*/fold

      11.8 Multiple-Valued Sequences

      11.9 Breaking an Iteration

      11.10 Iteration Performance

    12 Pattern Matching

    13 Classes and Objects

      13.1 Methods

      13.2 Initialization Arguments

      13.3 Internal and External Names

      13.4 Interfaces

      13.5 Final, Augment, and Inner

      13.6 Controlling the Scope of External Names

      13.7 Mixins

        13.7.1 Mixins and Interfaces

        13.7.2 The mixin Form

        13.7.3 Parameterized Mixins

      13.8 Traits

        13.8.1 Traits as Sets of Mixins

        13.8.2 Inherit and Super in Traits

        13.8.3 The trait Form

      13.9 Class Contracts

        13.9.1 External Class Contracts

        13.9.2 Internal Class Contracts

    14 Units (Components)

      14.1 Signatures and Units

      14.2 Invoking Units

      14.3 Linking Units

      14.4 First-Class Units

      14.5 Whole-module Signatures and Units

      14.6 Contracts for Units

        14.6.1 Adding Contracts to Signatures

        14.6.2 Adding Contracts to Units

      14.7 unit versus module

    15 Reflection and Dynamic Evaluation

      15.1 eval

        15.1.1 Local Scopes

        15.1.2 Namespaces

        15.1.3 Namespaces and Modules

      15.2 Manipulating Namespaces

        15.2.1 Creating and Installing Namespaces

        15.2.2 Sharing Data and Code Across Namespaces

      15.3 Scripting Evaluation and Using load

    16 Macros

      16.1 Pattern-Based Macros

        16.1.1 define-syntax-rule

        16.1.2 Lexical Scope

        16.1.3 define-syntax and syntax-rules

        16.1.4 Matching Sequences

        16.1.5 Identifier Macros

        16.1.6 set! Transformers

        16.1.7 Macro-Generating Macros

        16.1.8 Extended Example: Call-by-Reference Functions

      16.2 General Macro Transformers

        16.2.1 Syntax Objects

        16.2.2 Macro Transformer Procedures

        16.2.3 Mixing Patterns and Expressions: syntax-case

        16.2.4 with-syntax and generate-temporaries

        16.2.5 Compile and Run-Time Phases

        16.2.6 General Phase Levels

          16.2.6.1 Phases and Bindings

          16.2.6.2 Phases and Modules

        16.2.7 Syntax Taints

      16.3 Module Instantiations and Visits

        16.3.1 Declaration versus Instantiation

        16.3.2 Compile-Time Instantiation

        16.3.3 Visiting Modules

        16.3.4 Lazy Visits via Available Modules

    17 Creating Languages

      17.1 Module Languages

        17.1.1 Implicit Form Bindings

        17.1.2 Using #lang s-exp

      17.2 Reader Extensions

        17.2.1 Source Locations

        17.2.2 Readtables

      17.3 Defining new #lang Languages

        17.3.1 Designating a #lang Language

        17.3.2 Using #lang reader

        17.3.3 Using #lang s-exp syntax/module-reader

        17.3.4 Installing a Language

        17.3.5 Source-Handling Configuration

        17.3.6 Module-Handling Configuration

    18 Concurrency and Synchronization

      18.1 Threads

      18.2 Thread Mailboxes

      18.3 Semaphores

      18.4 Channels

      18.5 Buffered Asynchronous Channels

      18.6 Synchronizable Events and sync

      18.7 Building Your Own Synchronization Patterns

    19 Performance

      19.1 Performance in DrRacket

      19.2 The Bytecode and Just-in-Time (JIT) Compilers

      19.3 Modules and Performance

      19.4 Function-Call Optimizations

      19.5 Mutation and Performance

      19.6 letrec Performance

      19.7 Fixnum and Flonum Optimizations

      19.8 Unchecked, Unsafe Operations

      19.9 Foreign Pointers

      19.10 Regular Expression Performance

      19.11 Memory Management

      19.12 Reachability and Garbage Collection

      19.13 Weak Boxes and Testing

      19.14 Reducing Garbage Collection Pauses

    20 Parallelism

      20.1 Parallelism with Futures

      20.2 Parallelism with Places

      20.3 Distributed Places

    21 Running and Creating Executables

      21.1 Running racket and gracket

        21.1.1 Interactive Mode

        21.1.2 Module Mode

        21.1.3 Load Mode

      21.2 Scripts

        21.2.1 Unix Scripts

        21.2.2 Windows Batch Files

      21.3 Creating Stand-Alone Executables

    22 More Libraries

      22.1 Graphics and GUIs

      22.2 The Web Server

      22.3 Using Foreign Libraries

      22.4 And More

    23 Dialects of Racket and Scheme

      23.1 More Rackets

      23.2 Standards

        23.2.1 R5RS

        23.2.2 R6RS

      23.3 Teaching

    24 Command-Line Tools and Your Editor of Choice

      24.1 Command-Line Tools

        24.1.1 Compilation and Configuration: raco

        24.1.2 Interactive evaluation

        24.1.3 Shell completion

      24.2 Emacs

        24.2.1 Major Modes

        24.2.2 Minor Modes

        24.2.3 Packages specific to Evil Mode

      24.3 Vim

      24.4 Sublime Text

    Bibliography

    Index