From mboxrd@z Thu Jan  1 00:00:00 1970
From: Rafael <rvf0068@gmail.com>
Subject: Please help with a filter
Date: Tue, 02 Sep 2014 13:55:37 -0500
Message-ID: <87oauxetsm.fsf@gmail.com>
Mime-Version: 1.0
Content-Type: text/plain
Return-path: <emacs-orgmode-bounces+geo-emacs-orgmode=m.gmane.org@gnu.org>
Received: from eggs.gnu.org ([2001:4830:134:3::10]:52192)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <rvf0068@gmail.com>) id 1XOtF9-0003uC-OM
	for emacs-orgmode@gnu.org; Tue, 02 Sep 2014 14:56:00 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <rvf0068@gmail.com>) id 1XOtF0-0001P7-Nf
	for emacs-orgmode@gnu.org; Tue, 02 Sep 2014 14:55:51 -0400
Received: from mail-pd0-x22f.google.com ([2607:f8b0:400e:c02::22f]:43182)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <rvf0068@gmail.com>) id 1XOtF0-0001P2-Fk
	for emacs-orgmode@gnu.org; Tue, 02 Sep 2014 14:55:42 -0400
Received: by mail-pd0-f175.google.com with SMTP id ft15so9310603pdb.34
	for <emacs-orgmode@gnu.org>; Tue, 02 Sep 2014 11:55:40 -0700 (PDT)
Received: from ladell ([200.57.62.44])
	by mx.google.com with ESMTPSA id n2sm6500088pdh.41.2014.09.02.11.55.39
	for <emacs-orgmode@gnu.org>
	(version=TLSv1.2 cipher=RC4-SHA bits=128/128);
	Tue, 02 Sep 2014 11:55:40 -0700 (PDT)
List-Id: "General discussions about Org-mode." <emacs-orgmode.gnu.org>
List-Unsubscribe: <https://lists.gnu.org/mailman/options/emacs-orgmode>,
	<mailto:emacs-orgmode-request@gnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/archive/html/emacs-orgmode>
List-Post: <mailto:emacs-orgmode@gnu.org>
List-Help: <mailto:emacs-orgmode-request@gnu.org?subject=help>
List-Subscribe: <https://lists.gnu.org/mailman/listinfo/emacs-orgmode>,
	<mailto:emacs-orgmode-request@gnu.org?subject=subscribe>
Errors-To: emacs-orgmode-bounces+geo-emacs-orgmode=m.gmane.org@gnu.org
Sender: emacs-orgmode-bounces+geo-emacs-orgmode=m.gmane.org@gnu.org
To: Emacs-orgmode list <emacs-orgmode@gnu.org>


I want that the result of exporting to markdown the following two blocks
be identical:

#+begin_src org
  #+BEGIN_MARKDOWN
  <div class="sage">
    <script type="text/x-sage">2+3</script>
  </div>
  #+END_MARKDOWN
  
  #+BEGIN_SRC sage
    2+3
  #+END_SRC
#+end_src

I have tried the following, which seems similar to examples in the web,
and I think it should work, but it doesn't:

#+begin_src emacs-lisp
  (defun org-octopress-src-block (contents backend info)
    (when (eq backend 'md)
      (let (
  	  (lang (org-element-property :language info))
  	  (value (org-element-property :value info)))
        (message "Language is %s. Value is %s" lang value)
        (when (eq lang "sage" )
        (format
         "<div class=\"sage\">
         <script type=\"text/x-sage\">%s</script>
         </div>\n"
         value
         ))
        ))
    )
  
  (add-to-list 'org-export-filter-src-block-functions
  	     'org-octopress-src-block)
#+end_src

My debugging message says: 'Language is nil. Value is nil', so I cannot
get the name of the language from the source code. What should I do to
get the filter to work?

Thanks in advance,