assoc, assq, assv

assv( 
g_key 
l_alist 
) 
=> l_association / nil

Description

The assoc, assq, and assv functions find the first list in l_alist whose car field is g_key and return that list. assq uses eq to compare g_key with the car fields of the lists in alist. assoc uses equal. assv uses eqv.

The association list, l_alist, must be a list of lists. An association list is a standard data structure that has the form ((key1 value1) (key2 value2) (key3 value3) ...). These functions find the first list in l_alist whose car field is g_key and return that list. assq uses eq to compare g_key with the car fields of the lists in l_alist. assv uses eqv. assoc uses equal.

Arguments

g_key	An arbitrary object as the search key.
l_alist	Association list. Must be a list of lists.

Value Returned

l_association	The returned list is always an element of l_alist.
nil	If no list in l_alist has g_key, as its car.

Examples

e = '((a 1) (b 2) (c 3))
(assq 'a e) 
=> (a 1)

(assq 'b e) 
=> (b 2)

(assq 'd e) 
=> nil

(assq (list 'a) '(((a)) ((b)) ((c)))) 
=> nil

(assoc (list 'a) '(((a)) ((b)) ((c)))) 
=> ((a))

(assv 5 '((2 3) (5 7) (11 13))) 
=> (5 7)

Related Topics

eq

equal

eqv

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