An association list is a list of pairs where each pair is an association of a key to a datum. The pair is represented as a cons where the car is the key of the pair and the cdr is the datum.
assoc key list | Function |
assoc key list test | Function |
assoc
searches for a cons in list whose car is
eql
to key. If found, the cons is returned otherwise
nil
is returned. If the optional third argument test is
given it must be an Lpp Function of two arguments and assoc
will use it to do the test in place of eql
. For example:
let list1 = list(cons(L(1), L(2)), cons(L(2), L(4)), cons(L(3), L(6))); assoc(L(2), list1) => (2 . 4) assoc(L(4), list1) => nil let list1 = list(list(L("1"), L(2)), list(L("2"), L(4)), list(L("3"), L(6))); assoc(L("2"), list1) => nil assoc(L("2"), list1, L(stringEqual)) => ("2" 4)