[erlang-questions] Speaking of comments

Richard O'Keefe <>
Tue Dec 14 00:52:57 CET 2010


On 13/12/2010, at 8:19 PM, Edmond Begumisa wrote:

> Interesting article.
> 
> I don't know about using non-ASCII for actual source-code as the author suggests. I'm not a language designer so I have no opinion this (though in relation to this, I've sometimes wondered about alternatives to programing languages revolving around English -- it must really irritate non-English speakers, especially those coming from languages using non-latin alphabets.)

MADCAP used a non-ASCII character set, including 2d structures.
APL used (and uses) a non-ASCII character set.  It has no keywords.
I have seen Algol 60 programs written in French and Chinese.
I've also read Pascal in French (including French keywords)
and seen Simula 67 in Danish.
IBM mainframe compilers have for a long time allowed DBCS (double byte character sets).

Algol 60 was a comparatively straightforward case.  Technically, keywords in
that language are single characters, and their rendering as boldface or
underlined English words is just one of many possible hardware representations.
> 
> What I would love is very rich and flexible ways of attaching annotations or "running commentary" to source code.

Well, you _could_ use NuWeb, or NoWeb, or FunnelWeb, and add whatever annotations you like.

> I would think this could be done without changing the language in question.

Has very often been done.  People have even written programs with commentary in Microsoft Word
and used a VBA macro to strip out and save separately the text with the 'Program' style.  I
have my own very simple program for extracting <pre> sections, possibly restricted to a
particular class, from HTML so that
	html4.0 foo.htm | pre >foo.erl
can let you extract code from commentary.  How simple?

#include <stdio.h>
#include "dvm2.h"

int main(int argc, char **argv) {
    char *wanted = argc > 1 ? argv[1] : (char*)0;
    xml   e0 = load_esis_through(stdin, 0);
    int   last_was_nl;

    for_each_named_descendant(e0, "pre", e1)
        if (wanted != 0 && !has_value(e1, "class", wanted)) continue;
        last_was_nl = 1;
        for_each_text_descendant(e1, e2)
            fwrite(text_of(e2), 1, x_size(e2), stdout);
            if (x_size(e2) != 0)
                last_was_nl = text_of(e2)[x_size(e2)-1] == '\n';
        end_each_text_descendant
        if (!last_was_nl) putc('\n', stdout);
    end_each_named_descendant
    return 0;
}

That simple.  Doing the same kind of thing using xmerl would be very little harder.

Now you could handle parallel comments in HTML using

	<table width="100%">
	  <col width="50%" align="left"/>
          <col width="50%" align="left"/>
          <tbody>  <!-- repeat for each chunk -->
            <tr>
              <td><pre>code</pre></td>
              <td><p>comments</p></td>
            </tr>
	  </tbody>
	</table>

The limit has been our ingenuity, not our tools.\



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