为什么 cl-rassoc-if 不按预期工作?

Emacs-Lisp
1 
(setq fileset '(
                          (arch . ("a.txt" "b.txt" "c.txt" "d.txt" "e.txt"))
                          (emacs . ("f.txt" "g.txt"))
                          ))
(cl-rassoc-if (lambda (el)  (member "a.txt" (cdr el))) fileset)

我以为 cl-rassoc-if 结果会是 (arch . ("a.txt" "b.txt" "c.txt" "d.txt" "e.txt")), 结果是 nil, 这是为啥?

2 
cl-rassoc-if is an autoloaded byte-compiled Lisp function in
‘cl-seq.el’.

(cl-rassoc-if PREDICATE LIST [KEYWORD VALUE]...)

Find the first item whose cdr satisfies PREDICATE in LIST.

Keywords supported:  :key

[back]

pred 接受的是不是 alist 中的元素，是元素的 cdr 部分

(setq fileset '((arch . ("a.txt" "b.txt" "c.txt" "d.txt" "e.txt"))
                (emacs . ("f.txt" "g.txt"))))
(cl-rassoc-if (lambda (el) (member "a.txt" el)) fileset)
(arch "a.txt" "b.txt" "c.txt" "d.txt" "e.txt")
3

非常感谢! 我应该用 message 检查检查的