Re: Get value of Scheme function to display as a markup in Lilypond

[Aaron Hill]

On 2021-11-23 2:56 pm, Dimitris Marinakis wrote:
> Finally got to learn a bit of Scheme. I've made decent progress within 
> the
> Scheme sandbox. Now I'm trying to integrate a few things within 
> Lilypond.
>
> Let's say I have this function:
> #(define (dostuff x) (+ x 5))
>
> What would be the equivalent of #(display (dostuff 2)) but inside a
> Lilypond markup?
> So that if my Lilypond music code looks like that, I'll get the correct
> value from that function.
> {
> c^\markuptitle (placeholder) #2
> }
>
> I don't want the x argument to be displayed in the markup but rather 
> the
> result of the function.
>
> It's OK if this has to be broken into multiple steps.

One option is to format the output you want as a string and then include 
that in \markup:

####
#(define (dostuff x) (+ x 5))
\markup #(format #f "result = ~a" (dostuff 47))
####

If you just need the value, you could use number->string.  But for 
anything fancier, the formatted printing functionality is quite powerful 
and worth learning:

%%%%
\markup #(format #f "~{~a fish~^, ~}." '(one two red blue))
%%%%


-- Aaron Hill