set! -- r7rs Definition

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Kind

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syntax;

Implemented by

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• set! (from vonuvoli);

Syntax signature

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Syntax keywords:

• variable: identifier;
• expression: expression;

Syntax variants:

• (_ variable expression)

Exports

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• scheme:base -- (scheme base);

Exports recursive

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• scheme -- (scheme);

Description

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(set! <variable> <expression>)

Semantics: <Expression> is evaluated, and the resulting value is stored in the location to which <variable> is bound. It is an error if <variable> is not bound either in some region enclosing the set! expression or else globally. The result of the set! expression is unspecified.

(define x 2)
(+ x 1)                 ===>  3
(set! x 4)              ===>  #unspecified
(+ x 1)                 ===>  5

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The text herein was sourced and adapted as described in the "R7RS attribution of various text snippets" appendix.