From: Tim Visher <tim.visher@gmail.com>
To: emacs <help-gnu-emacs@gnu.org>
Subject: Generic `tree-seq` function definition?
Date: Fri, 6 Sep 2013 10:00:27 -0400 [thread overview]
Message-ID: <CAHa53uyOLORxvvAMV3rbZUSFC7f_5XGfdgTyz5D7Sa-J4q=yEQ@mail.gmail.com> (raw)
Hey everyone,
I'm trying to implement a generic `tree-seq` function (like [the one found
in clojure][]).
It seems very straightforward and other than translating some things
between Clojure and Elisp seemed like it should've gone off without a hitch.
But it doesn't work.
Can anyone venture a guess as to why?
The basic thing that seems to fail is that cl-labels doesn't seem to know
how to drop a local function into a map operation. You can see that from
the `one` function. When one is called directly it returns correctly but
when you try to map it it blows up in the same way.
(defun tree-seq (branch? children root)
(cl-labels ((walk (node)
(cons node
(if (funcall branch? node)
(cl-mapcan 'walk (cddr (funcall children
node)))))))
(walk root)))
(tree-seq 'file-directory-p
(lambda (directory)
(directory-files directory t))
"~/Dropbox/sensitive")
(cl-labels ((one (x)
(if (integerp x)
x
(one 10))))
(one (one 'a)))
;;; Boom!
;; (cl-labels ((one (x)
;; (if (integerp x)
;; x
;; (cl-mapcar 'one '(10 11 12)))))
;; (one (one 'a)))
https://gist.github.com/timvisher/6458093#file-sensitive-el-L31-L54
Thanks in advance!
--
In Christ,
Timmy V.
http://blog.twonegatives.com/
http://five.sentenc.es/ -- Spend less time on mail
next reply other threads:[~2013-09-06 14:00 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-06 14:00 Tim Visher [this message]
[not found] <mailman.1476.1378476077.10748.help-gnu-emacs@gnu.org>
2013-09-06 15:17 ` Generic `tree-seq` function definition? Stefan Monnier
2013-09-06 16:05 ` Tim Visher
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