SIMPLE-LENGTH returns the number of items in the top level of a list.

Examples:

• (SIMPLE-LENGTH ‘(a b c)) returns 3
• (SIMPLE-LENGTH ‘(a (b c))) returns 2
• (SIMPLE-LENGTH ‘(a b c (a (b c)))) returns 4


(defun SIMPLE-LENGTH (lst)
     (cond
          ((null lst) 0)
          (t (+ 1 (SIMPLE-LENGTH (cdr lst))))
     )
)


COMPLEX-LENGTH returns the numbers of atoms in a list no matter how deeply nested they are.

Examples:

• (COMPLEX-LENGTH ‘(a b c)) returns 3
• (COMPLEX-LENGTH ‘(a (b c))) returns 3
• (COMPLEX-LENGTH ‘(a b c (a (b c)))) returns 6


(defun COMPLEX-LENGTH (lst)
     (cond
          ((null lst) 0)
          ((atom (car lst)) (+ 1 (COMPLEX-LENGTH (cdr lst))))
          (t (+ (COMPLEX-LENGTH (car lst))
                (COMPLEX-LENGTH (cdr lst))
             )
          )
     )
)