(defun white-pawn-move (file rank)
  (let ((movelist '()))
    (if (and (within-boardp file (+ rank 1))
         (eql #\s (aref *board* (+ rank 1) file)))
    (push (cons file (+ rank 1)) movelist))
    (if (= rank 1)
    (push (cons file (+ rank 2)) movelist))
    (if (and (within-boardp (- file 1) (+ rank 1))
         (belongs-to-opponent (aref *board*  (+ rank 1) (- file 1))))
    (push (cons (- file 1) (+ rank 1)) movelist))
    (if (and (within-boardp (+ file 1) (+ rank 1))
         (belongs-to-opponent (aref *board* (+ rank 1) (+ file 1))))
    (push (cons (+ file 1) (+ rank 1)) movelist))
    movelist))

;refactor:
;file / rank numeric
(defun pawn-move (direction)
  (let ((startrank (if (eql direction #'+)
               1
               6)))
    (lambda (file rank)
      (let ((movelist '()))
      (if (and (within-boardp file (funcall direction rank 1))
           (eql #\s (aref *board* (funcall direction rank 1) file)))
          (push (cons file (funcall direction rank 1)) movelist))
      (if (= rank startrank)
          (push (cons file (funcall direction rank 2)) movelist))
      (if (and (within-boardp (- file 1) (funcall direction rank 1))
           (belongs-to-opponent (aref *board*  (funcall direction rank 1) (- file 1))))
          (push (cons (- file 1) (funcall direction rank 1)) movelist))
      (if (and (within-boardp (+ file 1) (funcall direction rank 1))
           (belongs-to-opponent (aref *board* (funcall direction rank 1) (+ file 1))))
          (push (cons (+ file 1) (funcall direction rank 1)) movelist))
    movelist))))
;desired usage
(setf (gethash #\P *move-table*) (pawn-move #'+))
(setf (gethash #\p *move-table*) (pawn-move #'-))