[Lisp] 九九乘法表

練習loop和collect的使用:

(loop for x from 1 to 9
      collect (loop for y from 1 to 9
                    collect (* x y)))

結果:
((1 2 3 4 5 6 7 8 9) (2 4 6 8 10 12 14 16 18) (3 6 9 12 15 18 21 24 27) (4 8 12 16 20 24 28 32 36) (5 10 15 20 25 30 35 40 45) (6 12 18 24 30 36 42 48 54) (7 14 21 28 35 42 49 56 63) (8 16 24 32 40 48 56 64 72) (9 18 27 36 45 54 63 72 81))

The Common Lisp Cookbook - The Loop Macro