评估Lisp中的函数

Question

我是Lisp的新手，需要帮助理解这个功能和(map length '((a b c) (1 2 3 4 5) (v1 v2 v3 v4 v5 v6))))

的评估

值为(3 5 6)

(define (map f list)    
  ; applies function f to each element of list
  (if (null? list) 
      ()
      (cons (f (car list)) 
            (map f (cdr list)))))

(define map-test-1
  (map square '(1 2 3 4 5)))
(define map-test-2
  (map length '((a b c) (1 2 3 4 5) (v1 v2 v3 v4 v5 v6))))