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grammar.md

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Common Lisp grammar

Each character has a syntax type, which is one of the following:

  • constituent
  • macro char
  • single escape
  • invalid
  • multiple escape
  • whitespace

http://www.lispworks.com/documentation/lw50/CLHS/Body/02_ad.htm

constituent and macro char characters are accumulated to make a token.

macro char characters can be either terminating or non-terminating, depending on whether they terminate a token. The only non-terminating macro character in standard syntax is sharpsign (#). The difference is that only non-terminating macro char can appear in the middle of a token, in which case it simply becomes a part of its name.

  • token - a number or a symbol.

Numbers

This grammar does not currently support potential numbers. They are treated as symbols.

See 2.3.1.1 Potential Numbers as Tokens.

Symbols

A token is a symbol if it is not:

  • a potential number
  • does not contain a package marker (unless escaped)
  • does not consist entirely of dots (unless at least one dot is escaped)

Some interesting examples:

(setf \. 1)
(+ \. 2) ; => 3

Glossary

  • package marker - the colon character (:)