define-values -- r7rs Definition

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Kind

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syntax;

Implemented by

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• define-values (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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(define-values <formals> <expression>)

Another kind of definition is provided by define-values, which creates multiple definitions from a single expression returning multiple values. It is allowed wherever define is allowed.

It is an error if a variable appears more than once in the set of <formals>.

Semantics: <Expression> is evaluated, and the <formals> are bound to the return values in the same way that the <formals> in a lambda expression are matched to the arguments in a procedure call.

(define-values (x y) (integer-sqrt 17))
(list x y) ===> (4 1)

(let ()
  (define-values (x y) (values 1 2))
  (+ x y))     ===> 3

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