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RE: [Axiom-developer] Re: noweb

From: Page, Bill
Subject: RE: [Axiom-developer] Re: noweb
Date: Fri, 5 May 2006 12:01:44 -0400

Ralf, Norman, Tim, et al. 

> Ralf Hemmecke wrote:
> > 
> > The only place where I think it would be necessary to 
> > escape <<  is if an = sign immediately follows the >>
> > AND the << starts at the first column. In all other
> > situations the line should be output by noweb literally
> > and NO error message should occurs. Maybe a WARNING (to 
> > stderr) would be nice, but still errcode=0.

On Friday, May 05, 2006 10:46 AM Norman Ramsey wrote:
> No.  Misspelled chunk names or missing chunks should result
> in errors, as should chunk names appearing in documentation.

As we all know this has been an "issue" in Axiom for some
time now since Tim Daly originally proposed a patch which
(essentially) implemented the behavior that Ralf suggests
above. At the time Norman also pointed out and provided
alternate code that implements this behavior using an
awk filter. Since all of Axiom's code depends on noweb,
I think it would be very nice to have this issue resolved.

The way I see it, what Ralf and Tim are suggesting is motivated
primarily by convenience for the author, i.e.  changing the
external source code as little as possible - even not at all -
when placing it inside a noweb literate program document.
But the reality is that any linear document syntax will
require some method of escaping external constructs that
conflict with the document syntax even if we do not wish to
place no other any limitation on the syntactical structure
of the external content. But this escape mechanism is only
an internal representation issue - something that we should
be very familiar with in the context of Axiom! :) The 'tangle'
and 'weave' operators make this escape mechanism invisible
on output.

Unfortunately developers still often use editing tools that
do not properly hide the internal representation of the
literate document so that on input the escape syntax can
sometimes seem quite inconvenient. I think the problem
really lies with these input tools and not with the internal
representation at all. As a minimum it would be nice to
have an "import tool" that coerces the external source code
syntax into the proper internal representation, i.e. something
that automatically adds the required escape codes. Even better
might be to have an editing "mode" (in emacs for example)
which recognizes and appropriately hides this coding for
the sake of convenience.

The bottom line here is that I agree with Norman that
modifying noweb's behavior is not the correct solution
and that if anything it should be more exact and strict.

Bill Page.

Bill Page.

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