Re: [Axiom-developer] Literate Programming -- Knuth interview

[daly]

On Mon, 2011-11-14 at 14:08 -0500, Eugene Surowitz wrote:
> Will your talk and slides be available on the web?

I gave a presentation at the Clojure Conj on Literate
Programming which was fairly well received but there were
no slides. I don't believe the talk was recorded.

I have an article in the Notices of the American Mathematical
Society scheduled to appear in February.

> 
> Long term objective excellent; getting there is the rub.
> It's ok at the developed and distributed level,
> but from the developer's ant eye view the toc and index
> are only as good as the choice of structure and
> the entry selection.

Indeed, that's a struggle for all authors. However, I have
made the index and cross references for every function and
variable.

> 
> There is also the headache of what the eyeball missed
> and what opinion bias does or does not consider important.
> Also texts tend to have concepts expressed as multiword
> strings, such as "table of contents".
> Pseudo-letters, such as "_" or "~", just add to the mess.

Every function, macro, and variable is introduced with
     \defun{foo}
     \defmacro{foo}
     \defvar{foo}

All of the index entries are hand generated using latex as in:
     \calls{foo}{bar}
which will put an entry under "foo" for "bar" and
an entry under "bar" for "foo". This means that it is trivial
to find every place that "bar" is called. This reverse-lookup
usually requires a code walker.

For global variables there are:
     \refsdollar{foo}{var}
     \defsdollar{foo}{var}
which will put an entry in the index for $var.


> 
> Exhaustive listing of everything was quite useful
> in another book effort.  For a code the size of Axiom,
> I guesstimate that a factor of three for the token file size.
> 
> Eugene J. Surowitz
> 
> On 11/12/2011 9:16 PM, daly wrote:
> > Well, the question is whether you're looking for a concept
> > (check table of contents) or a particular function (check
> > the index). At least that is the long term intention.
> >
> > On Fri, 2011-11-11 at 11:03 -0500, Eugene Surowitz wrote:
> >> I prefer the fountain pen for novelistic efforts.
> >>
> >> The issue that aroused my question has to do with
> >> comments that appear now and then in the list
> >> about knowing what is where in the source code.
> >>
> >> The reference to tools really was intended to address
> >> the idea of the utility of a mechanism(s) that could
> >> globally treat the entire source code as text to
> >> answer that question.
> >>
> >> Eugene J. Surowitz
> >>
> >> On 11/8/2011 4:42 PM, daly wrote:
> >>> Tools? The goal of literate programming is communicating from
> >>> human to human. It is like writing a novel. All you need is a
> >>> working Underwood typewriter and time.
> >>>
> >>> I tend to favor Latex because a lot of math is involved and
> >>> Latex prints math well. But I'm presenting a talk about
> >>> Literate Programming in North Carolina this week and I plan
> >>> to show examples that use XML, html, and video.
> >>>
> >>> Tim
> >>>
> >>> On Tue, 2011-11-08 at 15:03 -0500, Eugene Surowitz wrote:
> >>>> That literate programming is fully justified for Axiom is, well, almost 
> >>>> axiomatic.
> >>>> But the issue is more how to boost the ability to invert the process
> >>>> and reverse engineer non-literate code piles into literate documents.
> >>>>
> >>>> What, in your opinion, would be the most effective type of tool that 
> >>>> could
> >>>> be developed to render the literacy project more tractable?
> >>>>
> >>>> Eugene J. Surowitz
> >>>>
> >>>> On 11/8/2011 9:46 AM, address@hidden wrote:
> >>>>>> Yet to me, literate programming is certainly the most important thing
> >>>>>> that came out of the TeX project. Not only has it enabled me to write
> >>>>>> and maintain programs faster and more reliably than ever before, and
> >>>>>> been one of my greatest sources of joy since the 1980s -- it has
> >>>>>> actually been indispensable at times. Some of my major programs, such
> >>>>>> as the MMIX meta-simulator, could not have been written with any other
> >>>>>> methodology that I've ever heard of. The complexity was simply too
> >>>>>> daunting for my limited brain to handle; without literate programming,
> >>>>>> the whole enterprise would have flopped miserably.
> >>>>>>
> >>>>>> If people discover nice ways to use the newfangled multithreaded
> >>>>>> machines, I would expect the discovery to come from people who
> >>>>>> routinely use literate programming. Literate programming is what you
> >>>>>> need to rise above the ordinary level of achievement.
> >>>>>
> >>>>> I believe that Axiom's complexity is large enough to demand literate
> >>>>> programming. There are several reasons.
> >>>>>
> >>>>> First, computational mathematics requires people to be exceptional at
> >>>>> mathematics and programming. This is a small subset of already small
> >>>>> sets. We might as well add another subset of those who can communicate
> >>>>> their ideas in writing.
> >>>>>
> >>>>> Second, there are many design decisions that are necessary to reduce
> >>>>> a mathematical idea to implementation. Some of these design decisions
> >>>>> are mathematically arbitrary (e.g. branch cuts) or computationally
> >>>>> arbitrary (e.g. sparse versus dense) or programatically arbitrary
> >>>>> (e.g. all Spad versus Spad-and-lisp). These design decisions need to
> >>>>> be documented so people who maintain and modify the program know why
> >>>>> the decisions were made. Without this knowledge it would be trivial
> >>>>> to accidently destroy important optimizations.
> >>>>>
> >>>>> Third, nobody is an expert in the range of mathematics that Axiom can
> >>>>> and will implement. It is important to present some portions of the
> >>>>> theory associated with domains so people have a clue about the ideas
> >>>>> being encoded. Imagine what would happen if all of the math textbooks
> >>>>> only contained equations but no human-readable text. You might be able
> >>>>> to "read" a calculus textbook but not an infinite group theory textbook.
> >>>>>
> >>>>> Fourth, a million line program is too large to put into your head. You
> >>>>> need to have some background on the data structures, control flow, any
> >>>>> special tricks (e.g. funcalls through the symbol-plist), database
> >>>>> design, communication protocols (e.g. between Axiom and Hyperdoc and
> >>>>> Graphics), parsing structures, and a million other details. At best,
> >>>>> the code tells you HOW it does something but not WHY, not what it
> >>>>> depends on, not what depends on it, etc.
> >>>>>
> >>>>> Fifth, a program this large and this long-lived will eventually no
> >>>>> longer have the authors around to ask questions. Several of the Axiom
> >>>>> authors are already dead and most are not associated with it anymore.
> >>>>> Some of those authors are the world's expert in their subject matter.
> >>>>> That is a steep hill to climb if you want to understand the code,
> >>>>> especially if you have to debug or modify it.
> >>>>>
> >>>>> Sixth, in the 30 year horizon view, we need to pursue a new level of
> >>>>> excellence. As Knuth said:
> >>>>>
> >>>>>       "Literate programming is what you need to rise above
> >>>>>        the ordinary level of achievement"
> >>>>>
> >>>>> For all these reasons, and more, Axiom needs to be literate.
> >>>>>
> >>>>> Tim Daly
> >>>>>
> >>>>>
> >>>>>
> >>>>> _______________________________________________
> >>>>> Axiom-developer mailing list
> >>>>> address@hidden
> >>>>> https://lists.nongnu.org/mailman/listinfo/axiom-developer
> >>>>>
> >>>>>
> >>>>
> >>>>
> >>>> _______________________________________________
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> >>>
> >>>
> >>>
> >>>
> >
> >
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> >