Re: Groff algorithm

[John Gardner]

Both syntax highlighting and elegant algorithm specifications would make
great preprocessors. ;-) I find the latter works best when used tastefully
(and never, *ever* in a manual page).

It'd be trivial to write an Awk script for replacing basic-looking
keywords, substituting them with proper placement and formatting controls:

.begin algorithm
IsMultipleOf (input, value)

assert value is Integer

assert value is >= 0

value := 10

result := undefined

unless input % value

return true

else

return false

.end


This might expand to pic(1) instructions, eqn(1), or a list of steps for
human consumption like this one <https://tc39.es/ecma262/#sec-stringindexof>.
I vaguely recall somebody wrote a preprocessor to format *BNF grammars into
a pic(1) drawing that looked extremely spiffy. Sadly, I never saved the
link…




On Wed, 13 Jan 2021 at 07:23, M Douglas McIlroy <
m.douglas.mcilroy@dartmouth.edu> wrote:

> > I wonder how I can format a nice algorithm in the usual sense in groff.
> > I want to write pseudocode...\
>
> It all depends on what you mean by "nice". If it's just a properly indented
> listing, most of the standard macro packages have adequate support.
> For example, in the -ms package (man 7 groff_ms) bracket the code with
> .DS and .DE and use .ta to set tabs. However,. groff will not serve as a
> pretty-printer and decide how code should be indented.
>
> It's customary also to use a constant-width font for programs: .ft CW. But
> you
> may not want to do so for pseudocode.
>
> If you want syntax highlighting, e.g. bold keywords of (heaven forfend)
> syntax
> colorization. it will be painful, but straightforward: use \f and \m
> escapes to
> change font and color.
>
> Doug
>