How to add a \mark every 8 measures?

[Heather W. Reichgott]

Hello,

I'm working on a bunch of music for dance class accompanying. It is
very useful to have a mark above the barline every 8 measures. (Right
now, I go through my paper scores and make a pencil slash above the
barline every 8 measures for every piece I play.)

With Lilypond is there any way to create a function that will add a
mark every 8 measures? It doesn't so much matter what the mark is. I
would like something simple, like \mark "/", but if it has to be the
automatic alphabet marks that's ok too.

I understand that Scheme programming will probably be involved. My
Scheme is very rusty but I'm willing to give it a try.

thanks, Heather