Help on markups

[Carl D. Sorensen]

I've been (somewhat sporadically) trying to get guitar chord diagrams to
work.

I've figured out how to define a markup using def-markup-command (thanks
for a great feature!).

Now, I want to print a graphic element in the markup.  It looks to me
like I should be able to use the (dot x y) function found in
scm/output-tex.scm to create a string that will create an eps dot when
it's evaluated by gsview.

So I wrote the following markup definition:

#(def-markup-command (chord-diagram paper props chord-string) (string?)
  "Syntax: \\chord-diagram diagram-string
   eg: \\chord-diagram #\"x32010\" to achieve standard C chord"
    (interpret-markup paper props (markup (dot 0 0 3)))
  )

Hoping to be able to get a dot to come out.  Once I can get the dot, I
can also draw the lines and everything else needed to generate the chord
diagram.

But when I try to execute this markup, I get an error message that says
"Unbound variable: dot"

So I have two questions:

1) Is this the correct approach to get dots and lines into a markup?  If
not, what's a better approach?

2) If this is the right approach, how do I make use of the functions in
scm/output-tex.scm?

Thanks,

Carl Sorensen