assoc

associates a value to a key

Returns a newly mapped sequence wherein the specified key and value are associated. If the key already exists, the value replaces the one previously stored; otherwise the pair is added to the sequence.

An Example

(define robert {:name "Bob" :age 45})
(assoc robert :age 46)

This example returns a copy of robert wherein the value associated with :age has been replaced by the number 46. The original sequence is unaffected.