lisp - assoc 只是 find 的语法糖吗？

Question

CL-USER> *mylist*
((RED . 5) (RED . 4) (RED . 3) (BLUE . 5) (RED . 2) (BLUE . 4))
CL-USER> (assoc 'blue *mylist*)
(BLUE . 5)
CL-USER> (find 'blue *mylist* :key #'car)
(BLUE . 5)

在我看来 assoc 只是 find 的一个特例，这是真的还是我缺少 assoc 的一些额外功能> 这在这里不是很明显吗？

Answer 1

来自 clhs.lisp.se/Body/f_assocc.htm :

The two expressions

(assoc item list :test fn)

and

(find item list :test fn :key #'car)

are equivalent in meaning with one exception: if nil appears in alist in place of a pair, and item is nil, find will compute the car of the nil in alist, find that it is equal to item, and return nil, whereas assoc will ignore the nil in alist and continue to search for an actual cons whose car is nil.