[Axiom-developer] Re: [Axiom-mail] Re: noweb

[Ralf Hemmecke]

> | \begin{chunk}{MyCode} % The chunkname should not be optional!!
> | false
> | \end{chunk}
> | 
> | \begin{chunk}{MyChunk} % The chunkname should not be optional!!
> | apply(x: Boolean, y: Boolean): Boolean == x and y;
> | (x: Boolean)/(y: Boolean): Boolean == x and y;
> | MyCode: Boolean == true;
> | use: Boolean := true;
> | b: Boolean := MyCode /\ use/\use {MyCode} % How should that be parsed???
> | \end{chunk}

> | Doing that kind of programming in TeX is extremely difficult, since in
> | one place \ must be taken literally and in another it is considered as
> | a character that starts commands. If you want the code also reasonably
> | readable as a LaTeX source, I don't think that going the LaTeX way is
> | the right choice.

> Is this issue similar to that the package fancyvrb faces?

I haven't used fancyvrb, so I am not completely sure whether my 
reasoning is correct. But I have looked into the verbatim package. 
You'll probably believe that there are quite some tricks to recognise 
the \end{verbatim} in a stream of characters that TeX is actually 
supposed to output literally.

I bet even fancyvrb cannot correctly do a line like

b: Boolean := MyCode /\ use/\use {MyCode}

You could write

\begin{Verbatim}[commandchars=\\\{\}]
b: Boolean := MyCode /\ use/\use {MyCode}
\end{Verbatim}

That would probably correctly expand "\use {MyCode}", but the backslash 
after / is followed by a space and thus is expanded to output a space 
character. So in the output you would probably see something like

b: Boolean := MyCode / use/<MyCode>

where I wanted

b: Boolean := MyCode /\ use/<MyCode>

One must escape the first \ somehow in such a case. Doable, but it makes 
the code harder to read.

Of course you could write

\begin{Verbatim}[commandchars=|\{\}]
b: Boolean := MyCode /\ use/|use {MyCode}
\end{Verbatim}

and it would come out nicely, but then you have to make the 
corresponding tangle command a bit smarter to recognise | as the 
character that introduces TeX commands inside that Verbatim environment.

Anyway, fancyvrb seems to be quite smart, even though it does not solve 
the problem that in the output of the above code I would like see 
"Boolean" turn into a hyperlink to the definition of Boolean. 
Fortunately, the documentation of fancyvrb refers to the listings 
package for doing such fancy "pretty printing". But I have not yet 
looked into listings more closely.

Ralf