Lisps

Lisp refers to a family of programming languages characterized by the use of lists as the primary data structure and by code that can be manipulated as data. First implemented in 1958 by John McCarthy at the Massachusetts Institute of Technology, Lisp was designed for symbolic computation and artificial intelligence research. Its hallmark features include S-expressions for both code and data, automatic storage management, and a powerful macro system that enables language extension.

Programs in Lisp are typically written in a prefix notation using parentheses, and many dialects emphasize recursion and functional programming. Lisp is known for homoiconicity, the property that the program’s source code has the same structure as its data. This facilitates metaprogramming through macros, enabling users to create new syntactic constructs without changing the core language. Dynamic typing and first-class functions are common across widely used dialects.

Over time, several dialects have emerged. Lisp 1.5 and MacLisp influenced early systems; ANSI Common Lisp standardized the language in the 1980s and 1990s. Scheme, created in the 1970s as a minimalist dialect, influenced education and language design; Clojure, a modern Lisp on the Java Virtual Machine; Emacs Lisp used to extend the Emacs editor; and Racket (formerly PLT Scheme) as a platform for language-oriented programming.

Today, Lisp dialects are used in academic settings, symbolic computation, and niche industrial contexts. They continue to influence language design through powerful macro systems and emphasis on extensibility. While no longer as dominant as in earlier AI work, Lisp-derived ideas appear in many modern languages, and Lisp environments remain active in research, education, and specialized software projects.

Note: Lisp can also refer to a speech impediment, which is unrelated to the programming language.