With adjustable arrays it's easy: (defun vector-delete! (vector index) "Delete the element at INDEX from the given VECTOR. Destructively modifies the

With adjustable arrays it's easy: (defun vector-delete! (vector index) "Delete the element at INDEX from the given VECTOR. Destructively modifies the vector. The vector must have a fill-pointer. This is not thread-safe, use at your own risk. Examples: (let* ((x (make-array 4 :fill-pointer 4 :initial-contents '(1 2 3 4))) (y x)) (vector-delete! x 0) y) ;; => #(2 3 4)" (declare (type (Integer 0 *) index) (type Vector vector)) (assert (array-has-fill-pointer-p vector)) (let ((l (length vector))) (assert (< index l)) (let ((removed-element (aref vector index))) (loop :for i :from (1+ index) :below l :do (setf (aref vector (1- i)) (aref vector i))) (decf (fill-pointer vector)) removed-element))) (Granted, it could be done in 6 lines of code, but I'm already cringing at not providing a continuation when calling it with an out-of-bounds index)