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donate docs packages download version 7.9 is available. tenth Con, Oct 16-18, online , the Programming Language Mature Jet Fueled Extensible Robust Polished Vibrant Community #lang racket/gui ( define my-language 'English) ( define translations #hash([English . "Hello world"] [French . "Bonjour le monde"] [German . "Hallo Welt"] [Greek . "Γειά σου, κόσμε"] [Portuguese . "Olá mundo"] [Spanish . "Hola mundo"] [Thai . "สวัสดีชาวโลก"])) ( define my-hello-world ( hash-ref translations my-language "hello world")) ( message-box "" my-hello-world) 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 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 → In , 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 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 Guide Gradual Typing comes with support for major editors. The main bundle includes an innovative and extensible interactive development environment that has inspired other IDE projects. Dr Guide Dr Tools Emacs Integration VIM Integration Newcomers describe the on-line community as extremely friendly and helpful . Everyone is welcome to ask any question and everybody is welcome to contribute to the open-source code base. Mailing List Contributing Twitter Github , the Language-Oriented Programming Language Little Macros General Purpose Big Macros Easy DSLs IDE Support Any Syntax #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)? #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) 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 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. #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) 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 , and demonstrates a number of language features. Getting to know the full 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 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 programmer can thus combine functional with object-oriented components as needed. Some languages convey ideas more easily than others. And some programming languages convey solutions better than others. Therefore is a language for making languages , so that a programmer can write every module in a well-suited languages. 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. comes with its own IDE, Dr ( 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 Dr while using an alternative language, say Typed . macros, even complex ones and those used to make new languages, record and propagate a sufficient amount of source information for Dr to act as if it understood the features of the new language. 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. ’s ecosystem comes with parsing packages that allow developers to easily map any syntax to a parenthesized language, which is then compiled to ordinary with the help of ’s macro system. Such a language can also exploit the hooks of the IDE framework, so that its programmers may take advantage of ’s IDE. , the Ecosystem Software Tutorials & Documentation Community Books Education Swag Software Download Source Code Bug Reports Nightly Snapshot Builds Packages Tutorials & Documentation Quick Introduction Systems Programming The Guide The Reference Web Applications All Documentation Community Friendly environment policy Mailing lists and Blog #racket IRC on freenode.net Slack channel (Visit this link to sign up) @racketlang on Twitter channel on YouTube Team ’s development benefits from a large distributed pool of contributors. Software Freedom Conservancy Make a tax-deductible contribution to support our work. Books Realm of Learn to program with , one game at a time. Beautiful Make your own programming languages with . Server: Develop a web application with . All Books Education The Summer School a summer school for researchers, professionals, and (under)graduate students to the philosophy of programming languages Program by Design (aka TeachScheme!) a curriculum and training programfor high school teachers and college faculty Bootstrap a curriculum and training program for middle-school and high-school teachers Swag T-Shirts — the perfect way to meet friends, influence people, and stay warm. Stickers — the indispensable accessory f...