map-into

(map-into result-sequence function &rest sequences)

Applies function to successive elements of the given sequences and stores the results destructively into result-sequence -- which may be a list or a vector -- then returns result-sequence. The function is called with one element from each sequence in parallel, and iteration stops at the end of the shortest sequence, the result sequence included; any remaining elements of result-sequence are left unchanged. With no source sequences the function is called with no arguments to fill each element. A result with a fill pointer is filled up to that fill pointer.