list? -- r7rs Definition

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Kind

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type-predicate;

Extended by

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• proper-or-empty-list? (from vonuvoli);

Procedure signature

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Procedure variants:

• ((null) -> (true))
  • input: a value of type null;
  • output: a value of type true;
• ((list-proper) -> (true))
  • input: a value of type list-proper;
  • output: a value of type true;
• ((list-dotted) -> (false))
  • input: a value of type list-dotted;
  • output: a value of type false;
• ((list-circular) -> (false))
  • input: a value of type list-circular;
  • output: a value of type false;
• ((any) -> (false))
  • input: a value of type any;
  • output: a value of type false;

Exports

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• scheme:base -- (scheme base);

Exports recursive

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• scheme -- (scheme);

Description

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(list? obj)

Returns #t if obj is a list. Otherwise, it returns #f. By definition, all lists have finite length and are terminated by the empty list.

(list? '(a b c))     ===>  #t
(list? '())          ===>  #t
(list? '(a . b))     ===>  #f
(let ((x (list 'a)))
  (set-cdr! x x)
  (list? x))         ===>  #f

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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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• null;
• true;
• list-proper;
• list-dotted;
• false;
• list-circular;
• any;