(((meta (@ (content . "Symbolic Expression") (name . "title"))) (meta (@ (content . "manual") (name . "role"))) (meta (@ (content . "#manual #reference #zettelstore") (name . "tags"))) (meta (@ (content . "zmk") (name . "syntax"))) (meta (@ (content . "00001012000000 00001012920516 00001012920525 00001012921000 00001012931000") (name . "back"))) (meta (@ (content . "00001012000000 00001012920516 00001012920525 00001012921000 00001012931000") (name . "backward"))) (meta (@ (content . "1") (name . "box-number"))) (meta (@ (content . "(c) 2020-present by Detlef Stern <ds@zettelstore.de>") (name . "copyright"))) (meta (@ (content . "20230403145644") (name . "created"))) (meta (@ (content . "00001012930500") (name . "forward"))) (meta (@ (content . "en") (name . "lang"))) (meta (@ (content . "EUPL-1.2-or-later") (name . "license"))) (meta (@ (content . "20230403154010") (name . "modified"))) (meta (@ (content . "20230403154010") (name . "published"))) (meta (@ (content . "public") (name . "visibility")))) (p "A symbolic expression (also called " (em "s-expression") ") is a notation of a list-based tree." " " "Inner nodes are lists of arbitrary length, outer nodes are primitive values (also called " (em "atoms") ") or the empty list.") (p "A symbolic expression is either") (ul (li "a primitive value (" (em "atom") "), or") (li "a list of the form " (em "(E" (sub "1") " E" (sub "2") " … E" (sub "n") ")") ", where " (em "E" (sub "i")) " is itself a symbolic expression, separated by space characters.")) (p "An atom is a number, a string, or a symbol.") (p "Symbolic expressions are used in programming languages like LISP or Scheme, where they denote both data structures and the program itself." " " "This allows a LISP or Scheme program to process LISP or Scheme programs." " " "That property is also used within Zettelstore.") (p "Symbolic expressions are relatively easy to read, to parse, and to process.") (h2 (@ (id . "see-also")) "See also") (ul (li (a (@ (href . "00001012930500")) "Syntax") " of symbolic expressions in the Zettelstore") (li (a (@ (href . "https://en.wikipedia.org/wiki/S-expression") (rel . "external")) "S-expression @ Wikipedia"))))