[texhax] re-defining \vnotes in musixtex

[Bob Tennent]

It is possible to re-define the basic \vontes macro in
musixtex to achieve various effects.

For example,

 \def\vnotes#1\elemskip#2&#3\en
   {\noteskip#1\@l at mskip\@vnotes#3\enotes}

produces a single-instrument part from a two-instrument score,

 \def\vnotes#1\elemskip#2&#3\en
   {\noteskip#1\@l at mskip\@vnotes#2&\transpose+7#3\enotes}

transposes the second instrument an octave higher, and

 \def\vnotes#1\elemskip#2&#3\en
   {\noteskip#1\@l at mskip\@vnotes#3&#2\enotes}

will switch the order of the two instruments.  These all
have to be used within \makeatletter ... \makeatother
brackets.

I'd like to provide a user-friendly "front end" so that
users could write

  \transinstr{#2&#3}{#3}

  \transinstr{#2&#3}{#2&\transpose+7#3}

  \transinstr{#2&#3}{#3&#2}

or, even better,

  \transinstr{#1&#2}{#2}

  \transinstr{#1&#2}{#1&\transpose+7#2}

  \transinstr{#1&#2}{#2&#1}

and not have to deal with the \makeat... brackets, the
\elemskip argument and \@l at mskip\@vnotes.

Would this be feasible in TeX?  

Bob T.