Simplified Common Lisp reference
Symbol class: Sequences (Lists, Strings) and Arrays
Symbol type: function
vector-popvector => an object
Argument description:
vector a vector with fill pointer

VECTOR-POP function pops a element from specified vector. Supplied vector must have fill-pointer (see MAKE-ARRAY). Fill-pointer is decremented. The element to be popped is found at new fill-pointer position. See also MAKE-ARRAY, VECTOR-POP and VECTOR-PUSH. Return value is object found at previous end of vector.

(defparameter *v* (make-array 2 :fill-pointer 0)) => *V*
(vector-push 4 *v*) => 0
(vector-push 3 *v*) => 1
*v* => #(4 3)
(vector-pop *v*) => 3
(vector-pop *v*) => 4
Function indexFull documentation for vector-pop (HyperSpec)