paper scissors rock written in loop

test.lisp

;; Then, a winner for that round is selected: Rock defeats Scissors,
;; Scissors defeats Paper, and Paper defeats Rock. If both players
;; choose the same shape, the round instead ends in a draw.

(defun winner (a b)
  (loop with hands = (cons a b)
         and rules = '(((paper . scissors) second)
                       ((paper . rock) first)
                       ((rock . paper) second)
                       ((rock . scissors) first)
                       ((scissors . paper) first)
                       ((scissors . rock) second))
        for (rule answer) in rules
        when (equalp rule hands)
          do (return answer)
        finally (return 'draw)))