# The Lisp languages

While many other languages were designed to fix a problem, Lisp was formed strictly as a theoretical mathematical model in the hopes of creating [artificial intelligence](cs-ai.md).

- For that reason, it ends up being relatively timeless and somewhat of an abstraction unto itself, a bit like C.

For that reason, there are a *lot* of languages in the Lisp family:

- Maclisp (1966)
- MDL (1971)
- Scheme (1975)
- Ada (1980)
- Common Lisp (1984, with an ANSI standardization in 1994)
- [Emacs Lisp](cs-software-ide.md) (1985)
- [GNU Guile](cs-os-unix.md) (1993)
- Racket (1994, in the Scheme family)
- Clojure (2007)
- Lisp Flavored Erlang (2008)
- Hy (2013)
- Janet (2017)
- Bel (2019)

Lisp operates on a specific concept called REPL: read-eval-print loop. The idea is that it takes single user inputs,e xecutes them, and returns the result to the user. Interestly, [machine learning](cs-ai-ml.md) often produces the eval stage as text output in many language learning models.

## Specific dialects

Common Lisp is one of the more ubiquitous versions. It was approved by a committee, which means it made some design compromises.