member -- r7rs Definition

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Kind

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procedure;

Implemented by

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• member (from vonuvoli);

Procedure signature

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Procedure variants:

• ((any null) -> (false))
  • inputs:
    • a value of type any;
    • a value of type null;
  • output: a value of type false;
• ((any list-not-null) -> (list-not-null-or-false))
  • inputs:
    • a value of type any;
    • a value of type list-not-null;
  • output: a value of type list-not-null-or-false;
• ((any null procedure-2) -> (false))
  • inputs:
    • a value of type any;
    • a value of type null;
    • a value of type procedure-2;
  • output: a value of type false;
• ((any list-not-null procedure-2) -> (list-not-null-or-false))
  • inputs:
    • a value of type any;
    • a value of type list-not-null;
    • a value of type procedure-2;
  • output: a value of type list-not-null-or-false;

Exports

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• scheme:base -- (scheme base);

Exports recursive

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• scheme -- (scheme);

Description

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(memq obj list)
(memv obj list)
(member obj list)
(member obj list compare)

These procedures return the first sublist of list whose car is obj, where the sublists of list are the non-empty lists returned by (list-tail list k) for k less than the length of list. If obj does not occur in list, then #f (not the empty list) is returned. The memq procedure uses eq? to compare obj with the elements of list, while memv uses eqv? and member uses compare, if given, and equal? otherwise.

(memq 'a '(a b c))              ===>  (a b c)
(memq 'b '(a b c))              ===>  (b c)
(memq 'a '(b c d))              ===>  #f
(memq (list 'a) '(b (a) c))     ===>  #f
(member (list 'a)
        '(b (a) c))             ===>  ((a) c)
(member "B"
        '("a" "b" "c")
        string-ci=?)            ===>  ("b" "c")
(memq 101 '(100 101 102))       ===>  #unspecified
(memv 101 '(100 101 102))       ===>  (101 102)

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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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• any;
• null;
• false;
• list-not-null;
• list-not-null-or-false;
• procedure-2;