racket-lang.orgRacket

donate docs packages download version 8.12 is available. Con 2023 videos , 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 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 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 , 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 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 Polished 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 VS Code/Magic Emacs Integration Vim Integration , 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) 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. 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) 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. Big Macros 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. Easy DSLs 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 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 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. Any Syntax 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 Software Download Source Code Bug Reports Nightly Snapshot Builds Packages Tutorials & Documentation Tutorials & Documentation Quick Introduction Systems Programming The Guide The Reference Web Applications All Documentation Community Community Discourse and Discord These are the most active places for eers. Slack ( sign up ), IRC , Reddit , and Mailing lists eers are here, too! Mastodon , Twitter , and Blog Keep in touch. Wiki and YouTube Learn more from articles and talks. Team and Contributing ’s development benefits from a large distributed pool of contributors. Friendly Environment Policy Applies to all venues. Software Freedom Conservancy Make a tax-deductible contribution to support our work. Books 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 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 program for high school teachers and college faculty Bootstrap a curriculum and training program for middle-school and high-school teachers Swag Swag T-Shirts — the perfect way to meet friends, influence people, and stay warm. Stickers — the indispensable accessory for laptops and textbooks. Thank you To the NSF , DARPA , the Fund for the...