Re: [groff] A macro package for lists in TROFF

[Stephanie Björk]

To Ralph,

You quoted the following in your email:

> Stephanie wrote:
> > However, Troff's ability to take values of a numerical register and
> > use it as a name to another register (.nr my_\na_\nb) intrigues me
> > very much.
>
> I do not know if that "feature" was an intentional design or an
> accident, and I do not know either if it is considered a good practice
> or an abuse to take advantage of it, but I find it very useful.

Unfortunately, I've tried looking for the email to my inbox that was the
reply to my writing about Troff's ability to .... .
It seems to be a technical issue that I didn't receive that email.

I was wondering if you could send it to me again, quoted, so I can follow
from the context?

Thanks.

Stephanie

On Thu, Dec 7, 2017 at 5:57 AM, Ralph Corderoy <address@hidden>
wrote:

> Hello you two,
>
> > Stephanie wrote:
> > > However, Troff's ability to take values of a numerical register and
> > > use it as a name to another register (.nr my_\na_\nb) intrigues me
> > > very much.
> >
> > I do not know if that "feature" was an intentional design or an
> > accident, and I do not know either if it is considered a good practice
> > or an abuse to take advantage of it, but I find it very useful.
>
> I don't know if `intentional' is the right word, more likely `obvious'
> for the time.  If you've only ever been used to `macros' as seen in C's
> cpp(1) then you haven't been exposed to the more powerful macros that
> were common to aid the simpler languages of the time, e.g. assembler.
>
> Today, m4(1) is still around from that era, along with troff, and is
> worth examining.  https://en.wikipedia.org/wiki/M4_(computer_language)
> autoconf and sendmail still use it.  And some years ago now, I
> supplemented a BCPL-like language that only offered the machine word.
> It was used to add `probes' to executables without recompiling.  Fine
> for small things, but it was pushed into more complex tasks and chasing
> through structs and pointers with nothing but arithmetic because tedious
> for its users so I used m4 to provide `struct'-defining statements that
> in turn defined more macros that would do the member accesses and
> pointer dereferences given based addresses, all based on the identifiers
> used in the executable's source.
>
> Lisp also takes macros to town.  Both code and data are lists in Lisp,
> and macros allow manipulating those lists during `parsing'.  A skilled
> Lisp zealot writes any non-trivial program in a unique dialect of Lisp,
> having cajoled the language with macros to fit the domain.  I don't say
> this in praise, just as another data point.  :-)
>
> --
> Cheers, Ralph.
> https://plus.google.com/+RalphCorderoy
>