A function to calculate n rows of Pascal's Triangle

pascal.lisp

(defun triangle (num)
  "Generate num rows of Pascal's Triangle"
  (labels ((next-row (row last-num)
	     (cond ((null row) '(1))
		   (t (cons (+ last-num (car row))
			    (next-row (cdr row) (car row))))))
	   (triangle-b (num prev-row)
	     (cond ((= num 0) '())
		   (t (cons prev-row
			    (triangle-b (1- num)
					(next-row prev-row 0)))))))
    (triangle-b num '(1))))