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 Racket
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Racket version 8.14 is available.

RacketCon 2024
Racket, the Programming Language

#lang racket/gui

(define my-language 'English)

(define translations
  #hash([Chinese . "你好 世界"]
        [English . "Hello world"]
        [French . "Bonjour le monde"]
        [German . "Hallo Welt"]
        [Greek . "Γειά σου, κόσμε"]
        [Portuguese . "Olá mundo"]
        [Spanish . "Hola mundo"]
        [Thai . "สวัสดีชาวโลก"]
        [Turkish . "Merhaba Dünya"]))

(define my-hello-world
  (hash-ref translations my-language
            "hello world"))

(message-box "" my-hello-world)

Mature

Racket is a mature and stable product. From the beginning, it has supported
cross-platform graphical programming (Windows, macOS, Linux).

 * Package System
 * GUI Framework
 * Standalone Binaries
 * Foreign Interface

Practical

Racket includes a rich set of libraries, covering the full range from web server
apps to mathematics and scientific simulation software.

 * Web Applications
 * Database
 * Math & Statistics
 * Full List →

Extensible

In Racket, programmers define their own loops with powerful macros. Indeed,
these macros are so powerful that programmers make entire domain-specific
languages as libraries. No tools, no Makefiles required.

 * Intro To Macros
 * Macros In Depth
 * Making New Languages
 * Sample #Langs

Robust

Racket is the first language to support higher-order software contracts and safe
gradual typing. Programmers can easily deploy these tools to harden their
software.

 * The Contract Guide
 * High-Order Contracts
 * The Typed Racket Guide
 * Gradual Typing

Polished

Racket comes with support for major editors. The main bundle includes an
innovative and extensible interactive development environment that has inspired
other IDE projects.

 * DrRacket Guide
 * VS Code/Magic Racket
 * Emacs Integration
 * Vim Integration

Racket, the Language-Oriented Programming Language

#lang typed/racket

;; Using higher-order occurrence typing
(define-type SrN (U String Number))
(: tog ((Listof SrN) -> String))
(define (tog l)
  (apply string-append
         (filter string? l)))
(tog (list 5 "hello "
           1/2 "world" (sqrt -1)))

#lang scribble/base

@; Generate a PDF or HTML document
@(require (only-in racket ~a))
@(define N 99)
@title{Bottles: @italic{Abridged}}
@(apply
  itemlist
  (for/list ([n (in-range N 0 -1)])
    @item{@(~a n) bottles.}))

#lang datalog

ancestor(A, B) :- parent(A, B).
ancestor(A, B) :-
  parent(A, C), ancestor(C, B).
parent(john, douglas).
parent(bob, john).
ancestor(A, B)?

Little Macros

#lang racket

(provide time-it)

(require (for-syntax syntax/parse))

(define-syntax (time-it stx)
  (syntax-parse stx
    [(_ task)
     #'(thunk-time-it (λ () task))]))

(define (thunk-time-it task)
  (define before (cim))
  (define answer (task))
  (define delta  (- (cim) before))
  (printf "time: ~a ms\n" delta)
  answer)

(define cim current-inexact-milliseconds)

Racket allows programmers to add new syntactic constructs in the same way that
other languages permit the formulation of procedures, methods, or classes. All
you need to do is formulate a simple rule that rewrites a custom syntax to a
Racket expression or definition.

Little macros can particularly help programmers with DRY where other features
can’t. The example on the left above shows how to define a new syntax for
measuring the time a task takes. The syntax avoids the repeated use of lambda.
Note also how the macro is exported from this module as if it were an ordinary
function.

General Purpose

#lang racket/gui

;; let's play a guessing game

(define frame (new frame% [label "Guess"]))

(define secret (random 5))
(define ((check i) btn evt)
  (define found? (if (= i secret) "Yes" "No"))
  (message-box "?" found?)
  (when (= i secret)
    (send frame show #false)))

(for ([i (in-range 5)])
   (new button%
        [label (~a i)]
        [parent frame]
        [callback (check i)]))

(send frame show #t)

Racket comes with a comprehensive suite of libraries: a cross-platform GUI
toolbox, a web server, and more. Thousands of additional packages are a single
command away: 3D graphics, a bluetooth socket connector, color maps, data
structures, educational software, games, a quantum-random number generator,
scientific simulations, web script testing, and many more.

Macros work with these tools. The example on the left above shows the
implementation of a small number-guessing game. It is implemented in the GUI
dialect of Racket, and demonstrates a number of language features.

Big Macros

Getting to know the full Racket macro system will feel liberating, empowering,
dazzling—like a whole new level of enlightenment. Developers can easily create a
collection of co-operating macros to implement algebraic pattern matching,
simple event-handling, or a logic-constraint solver.

While Racket is a functional language, it has offered a sub-language of classes
and objects, mixins and traits, from the beginning. The macro-based
implementation of a Java-like class system lives in a library and does not need
any support from the core language. A Racket programmer can thus combine
functional with object-oriented components as needed.

Easy DSLs

Some languages convey ideas more easily than others. And some programming
languages convey solutions better than others. Therefore Racket is a language
for making languages, so that a programmer can write every module in a
well-suited language.

Often an application domain comes with several languages. When you need a new
language, you make it—on the fly. Open an IDE window; create a language right
there, with just a few keystrokes; and run a module in this new language in a
second IDE window. Making new languages really requires no setup, no project
files, no external tools, no nothing.

IDE Support

Racket comes with its own IDE, DrRacket (née DrScheme), and it sports some
unique features. For example, when a programmer mouses over an identifier, the
IDE draws an arrow back to where it was defined.

A programmer immediately benefits from DrRacket while using an alternative
language, say Typed Racket. Racket macros, even complex ones and those used to
make new languages, record and propagate a sufficient amount of source
information for DrRacket to act as if it understood the features of the new
language.

Any Syntax

Racket programmers usually love parentheses, but they have empathy for those who
need commas and braces. Hence, building languages with conventional surface
syntax, like that of datalog, is almost as easy as building parenthetical
languages.

Racket’s ecosystem comes with parsing packages that allow developers to easily
map any syntax to a parenthesized language, which is then compiled to ordinary
Racket with the help of Racket’s macro system. Such a language can also exploit
the hooks of the IDE framework, so that its programmers may take advantage of
Racket’s IDE.

Racket, the Ecosystem

Software
Software



Download Racket

Source Code

Bug Reports

Nightly Snapshot Builds

Packages





Tutorials & Documentation
Tutorials & Documentation



Quick Introduction

Systems Programming

The Racket Guide

The Racket Reference

Web Applications

All Documentation





Community
Community





Discourse and Discord
These are the most active places for Racketeers.

Slack (sign up), Reddit, and Mailing lists
Racketeers are here, too!

Mastodon, Twitter, and Blog
Keep in touch.

Wiki and YouTube
Learn more from articles and talks.

Team and Contributing
Racket’s development benefits from a large distributed pool of contributors.

Friendly Environment Policy
Applies to all Racket venues.

Software Freedom Conservancy
Make a tax-deductible contribution to support our work.





Books
Books





The Racket Guide
A detailed overview of the Racket Language.

Realm of Racket
Learn to program with Racket, one game at a time.

Beautiful Racket
Make your own programming languages with Racket.

Server: Racket
Develop a web application with Racket.

All Racket Books





Education
Education





The Racket Summer School
a summer school for researchers, professionals, and (under)graduate students to
the Racket philosophy of programming languages

Program by Design (aka TeachScheme!)
a curriculum and training program for high school teachers and college faculty

Bootstrap
a curriculum and training program for middle-school and high-school teachers





Swag
Swag



Racket T-Shirts — the perfect way to meet friends, influence people, and stay
warm.

Racket Stickers — the indispensable accessory for laptops and textbooks.



Thank you
To the NSF,
DARPA,
the Fund for the Improvement of Postsecondary Education (FIPSE) at the US
Department of Education,
the Exxon Foundation,
CORD, partners of the Academy of Information Technology,
Microsoft,
Mozilla,
Google,
and many individuals
for their generous support over the years.