Re: process man(7) (or any other package of macros) without typesetting

[Lennart Jablonka]

> The problem is that at no point you can have the .roff source, after
> the man(7) macros have been expanded.  Would it be possible to split
> the groff(1) pipeline to have one more preprocessor, let's call it
> woman(1) (because man(1) is already taken), so that it translates
> man(7) to roff(7)?  I'd like to be able to do this:
>
>         $ preconv            foo.1p      >foo.1p.tbl
>         $ tbl               <foo.1p.tbl  >foo.1p.eqn
>         $ eqn -Tutf8        <foo.1p.eqn  >foo.1p.man
>         $ woman -Tutf8      <foo.1p.man  >foo.1p.roff
>         $ troff -Tutf8      <foo.1p.roff >foo.1p.set
>         $ grotty -c         <foo.1p.set  >foo.1p.cat

It couldn’t work with a preprocessor with any degree of 
generality.¹   The macro definitions themselves are entirely 
context-dependent;  the easiest thing to point to for that is 
changing the control characters.

        .cc c
        cde m
        .\" ...
        ..

There are countless examples requiring such a preprocessor to 
interpret the troff language.

What might be possible is a mode for troff that emits text and 
control lines every time nodes would be added to the internal 
buffer.   (Or something;  I don’t know the internals.)   Though 
that would absorb the environment’s effects, like the nroff/troff 
distinction, that should be applied when the document is rendered.   
What might be fun is writing a postprocessor that emits troff, 
though the resulting troff would look even uglier than that of 
a mode of troff the program.

Oh, and do note that mandoc likely wouldn’t be able to render such 
documents nicely.

Easier options are:

 a) letting man-db accept trout man pages, with the same issue 
    with mandoc

 b) bundling the macros with the man pages with a little .so at 
    the start, with the same issue with mandoc

 c) shipping pre-rendered cat pages, with little annoyances such 
    as the inability to render the man page at different sizes or 
    disabling SGR mode or using a different encoding

> With man(7) alone, it's already interesting to have this for
> debugging purposes.  But I envision a more useful thing: POSIX uses
> mm(7) for their manual pages.  Ideally, I'd like to keep their
> sources with minimal modification in man-pages-posix.  But of course,
> man(1) only understands man(7) and mdoc(7).  If we add a mm(1)
> program that is the mm(7) equivalent of woman(1), then I'd be able
> to install a preprocessed page, with the following pipeline, and
> man(1) should be able to render it, I guess:
>
>         $ preconv            foo.1p     >foo.1p.tbl
>         $ tbl               <foo.1p.tbl >foo.1p.eqn
>         $ eqn -Tutf8        <foo.1p.eqn >foo.1p.man
>         $ mm -Tutf8         <foo.1p.man >foo.1p.roff
>         $ install            foo.1p.roff /usr/man/man1p/foo.1p

Btw, mm(1) is already taken for a System V script roughly similar 
to troff -mm "$@" with a few extra options for specifying the use 
of preprocessors or nroff.   I don’t see value in having 
specialized programs for different macro packages in this way, for 
that purpose or for this.

¹ The use of preprocessors that don’t parse troff is a hack 
anyway.   If usually not much of a concern, it is annoying if you 
need to replace

        .cc @
        @       EQ

by

        .cc @
        .EQ

(Not that I often use .cc.)