(defun least (l &optional (filter #'identity))
  (let ((out most-positive-fixnum))
    (dolist (x l out)
      (let ((x1 (funcall filter x)))
        (if (< x1 out)
            (setf out x1))))))

(defun most (l &optional (filter #'identity))
  (let ((out most-negative-fixnum))
    (dolist (x l out)
      (let ((x1 (funcall filter x)))
        (if (> x1 out)
            (setf out x1))))))