map

(map result-type function &rest sequences)

Applies function to successive elements of the given sequences -- each of which may be a list or a string -- and builds a result of the requested type. When several sequences are given, the function is called with one element from each and iteration stops at the end of the shortest sequence. result-type must be written as a literal designator (resolved statically, like concatenate): 'list collects the results into a list, 'string builds a string from the character results, and nil calls the function only for its side effects and returns nil.