R4RS

Scheme

Paradigms	Multi-paradigm (functional procedural meta)
Designed by	Guy L. Steele Gerald Jay Sussman
First appeared	1970; 47 years ago (1970)
Stable release	R7RS (ratified standard) / 2013; 4 years ago (2013)
Typing discipline	Strong Dynamic
Scope	lexical
Filename extensions	.scm   .ss
Website	www.scheme-reports.org
Major implementations
Many (see Category:Scheme (programming language) implementations)
Dialects
T
Influenced by
Lisp ALGOL MDL
Influenced
Clojure Common Lisp Dylan EuLisp Haskell Hop JavaScript Julia Lua R S Racket Ruby Rust Scala

Scheme is a functional programming language and one of the two main dialects of the programming language Lisp. Unlike Common Lisp, the other main dialect, Scheme follows a minimalist design philosophy specifying a small standard core with powerful tools for language extension.

Scheme was created during the 1970s at the MIT AI Lab and released by its developers, Guy L. Steele and Gerald Jay Sussman, via a series of memos now known as the Lambda Papers. It was the first dialect of Lisp to choose lexical scope and the first to require implementations to perform tail-call optimization, giving stronger support for functional programming and associated techniques such as recursive algorithms. It was also one of the first programming languages to support first-class continuations. It had a significant influence on the effort that led to the development of Common Lisp.

The Scheme language is standardized in the official IEEE standard and a de facto standard called the Revisedⁿ Report on the Algorithmic Language Scheme (RnRS). The most widely implemented standard is R5RS (1998); a new standard, R6RS, was ratified in 2007. Scheme has a diverse user base due to its compactness and elegance, but its minimalist philosophy has also caused wide divergence between practical implementations, so much that the Scheme Steering Committee calls it "the world's most unportable programming language" and "a family of dialects" rather than a single language.