promise? -- r7rs Definition

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Kind

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type-predicate;

Extended by

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• promise? (from vonuvoli);

Procedure signature

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Procedure variants:

• ((promise) -> (true))
  • input: a value of type promise;
  • output: a value of type true;
• ((any) -> (false))
  • input: a value of type any;
  • output: a value of type false;

Exports

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• scheme:lazy -- (scheme lazy);

Exports recursive

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• scheme -- (scheme);

Description

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(promise? obj)

The promise? procedure returns #t if its argument is a promise, and #f otherwise. Note that promises are not necessarily disjoint from other Scheme types such as procedures.

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

Referenced-types

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• promise;
• true;
• any;
• false;