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Kawa, the Java-based Scheme system

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7.4 Keywords

Keywords are similar to symbols. The main difference is that keywords are self-evaluating and therefore do not need to be quoted in expressions. They are used mainly for specifying keyword arguments.

keyword ::= identifier:

An alternative syntax, with the colon first, is supported for compatibility with Common Lisp and some other Scheme implementations:

keyword ::= :identifier

Putting the colon first has exactly the same effect as putting it last; putting is last is recommended, and is how keywords are printed.

A keyword is a single token; therefore no whitespace is allowed between the identifier and the colon (which is not considered part of the name of the keyword).

Function: keyword? obj
Return #t if obj is a keyword, and otherwise returns #f.

Function: keyword->string keyword
Returns the name of keyword as a string. The name does not include the final #\:.

Function: string->keyword string
Returns the keyword whose name is string. (The string does not include a final #\:.)

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  Copyright 2003   by The Free Software Foundation     Updated Jun 2003