Table of Contents for Programming Languages: a survey

Lisps (in general)

Lisp is a language family, not a single language. In lists of popular or beloved languages, "Lisp" often comes up, but it's unclear which "Lisp" is the most popular or beloved among the Lisps.

Common Lisp and Scheme are sometimes identified as the two most popular Lisp dialects (eg. "Today, the most widely known general-purpose Lisp dialects are Common Lisp and Scheme." -- [1]).

In online discussions about Lisp, I get the impression that the following four variants or subfamilies are the most popular or talked about:

• Common Lisp
• Scheme
• Clojure
• Elisp

Common Lisp is a committee-based standardization that was intended to unify a handful of (but not all) existing Lisp projects and dialects in the early 80s (to place this in context, Lisp was invented in 1958, so there were already a number of Lisp variants and descendents by 1980). It gained a lot of momentum and many commercial implementations of it were written. It is standardized but does not have a canonical implementation. It is said to be a 'large' language, and a good practical choice for getting real projects done in Lisp.

Scheme is a more minimal Lisp invented in 1975 (or, some would say, between 1975 and 1980), which also supports some features common lisp doesn't, such as a language primitive for first-class continuations (also, tail call optimization is required by the Scheme spec but not by the Common Lisp spec). It permits a functional style of programming. It is said to be small and elegant. It is standardized but does not have a canonical implementation. One Scheme variant, Racket, is said to have advanced facilities for metaprogramming and for prototyping new programming language features.

Clojure is a more recent (2007) Lisp variant. It compiles to the JVM and is known for its embrace of immutable data structures and its focus on cuncurrency constructs. It has a canonical implementation but is not standardized.

Elisp (started around 1984 or 1985 [2] [3]) is a language purpose-built for Emacs, a popular text editor software application. Most of Emacs is implemented in Elisp; Elisp is exposed to the user, who can use it as a scripting language to create Emacs extensions or to modify the behavior of Emacs. Because Emacs is used by many people, Elisp is used by many people; however, Elisp is not much used for anything outside of Emacs. Furthermore, Elisp's creator now promotes GNU Guile, a Scheme implementation, over Elisp (although Guile can also run Elisp) [4]