Racket is a general-purpose, multi-paradigm programming language. The Racket language is a modern dialect of Lisp and a descendant of Scheme. It is designed as a platform for programming language design and implementation. In addition to the core Racket language, Racket is also used to refer to the family of programming languages and set of tools supporting development on and with Racket. Racket is also used for scripting, computer science education, and research. The Racket platform provides an implementation of the Racket language, including a runtime system, libraries, and compiler supporting several compiler modes: machine code, cross-platform, interpreted, and just-in-time compilation (JIT) along with the DrRacket integrated development environment (IDE) written in Racket. Racket is used by the ProgramByDesign outreach program, which aims to turn computer science into "an indispensable part of the liberal arts curriculum". The core Racket language is known for its extensive macro system which enables creating embedded and domain-specific languages, language constructs such as classes or modules, and separate dialects of Racket with different semantics. The platform distribution is free and open-source software distributed under the Apache 2.0 and MIT licenses. Extensions and packages written by the community may be uploaded to Racket's package catalog.
History
Development Matthias Felleisen founded PLT Inc. in the mid 1990s, first as a research group, soon after as a project dedicated to producing pedagogic materials for novice programmers (lectures, exercises/projects, software). In January 1995, the group decided to develop a pedagogic programming environment based on Scheme. Matthew Flatt cobbled together MrEd, the original virtual machine for Racket, from libscheme, wxWidgets, and a few other free systems. In the years that followed, a team including Flatt, Robby Findler, Shriram Krishnamurthi, Cormac Flanagan, and many others produced DrScheme, a programming environment for novice Scheme programmers and a research environment for gradual typing. The main development language that DrScheme supported was named PLT Scheme. In parallel, the team began conducting workshops for high school teachers, training them in program design and functional programming. Field tests with these teachers and their students provided essential clues for directing the development. Over the following years, PLT added teaching languages, an algebraic stepper, a transparent read–eval–print loop, a constructor-based printer, and many other innovations to DrScheme, producing an application-quality pedagogic program development environment. By 2001, the core team (Felleisen, Findler, Flatt, Krishnamurthi) had also written and published their first textbook, How to Design Programs, based on their teaching philosophy. The Racket Manifesto details the principles driving the development of Racket, presents the evaluation framework behind the design process, and details opportunities for future improvements.
Version history The first generation of PLT Scheme revisions introduced features for programming in the large with both modules and classes. Version 42 introduced units – a first-class module system – to complement classes for large scale development. The class system gained features (e.g., Java-style interfaces) and also lost several features (e.g. multiple inheritance) throughout these versions. The language evolved throughout a number of successive versions, and gaining milestone popularity in Version 53, leading to extensive work and the following Version 100, which would be equivalent to a "1.0" release in current popular version systems. The next major revision was named Version 200, which introduced a new default module system that cooperates with macros. In particular, the module system ensures that run-time and compile-time computation are separated to support a "tower of languages". Unlike units, these modules are not first-class objects. Version 300 introduced Unicode support, foreign library support, and refinements to the class system. Later on, the 300 series improved the performance of the language runtime with an addition of a JIT compiler and a switch to a default generational garbage collection. By the next major release, the project had switched to a more conventional sequence-based version numbering. Version 4.0 introduced the #lang shorthand to specify the language that a module is written in. Further, the revision introduced immutable pairs and lists, support for fine-grained parallelism, and a statically-typed dialect. On 7 June 2010, PLT Scheme was renamed Racket. The renaming coincided with the release of Version 5.0. Subsequently, the graphical user interface (GUI) backend was rewritten in Racket from C++ in Version 5.1 using native UI toolkits on all platforms. Version 5.2 included a background syntax checking tool, a new plotting library, a database library, and a new extended REPL. Version 5.3 included a new submodule feature for optionally loaded modules, new optimization tools, a JSON library, and other features. Version 5.3.1 introduced major improvements to DrRacket: the background syntax checker was turned on by default and a new documentation preview tool was added. In version 6.0, Racket released its second-generation package management system. As part of this development, the principal DrRacket and Racket repository was reorganized and split into a large set of small packages, making it possible to install a minimal racket and to install only those packages needed. Version 7 of Racket was released with a new macro expander written in Racket as part the preparations for supporting moving to the Chez Scheme runtime system and supporting multiple runtime systems. On 19 November 2019, Racket 7.5 was released. It had a less restrictive license – either the Apache 2.0 license or the MIT license. On 13 February 2021, Racket 8.0 was released. Racket 8.0 marks the first release where Racket with the Chez Scheme runtime system, known as Racket CS, is the default implementation. Racket CS is faster, easier to maintain and develop, backward-compatible with existing Racket programs, and has better parallel garbage collection.
Features
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