Re: Scheme help request: How can else of an if-statement be made to do nothing?

[Jean Abou Samra]

Hi,

Le 17/10/2020 à 19:27, Matthew Fong a écrit :

> Hello Richard,
>
> I just discovered your explanation is in fact the case, and also 
> concluded cond wouldn't work either.
>
> I might have to settle for an empty markup block for now.

The point of interpret-markup is to turn a markup into a stencil, so I'd 
use empty-stencil:

\version "2.20.0"

#(define-markup-command (print-if-defined layout props sym text)
                        (symbol? markup?)
  (if (defined? sym)
      (interpret-markup layout props
        #{ \markup \with-color #'(0.8 0.2 0.2) #text #})
      empty-stencil))

symA = "Something"

\markup {
  \print-if-defined #'symA "Text"
  \print-if-defined #'symB "More text"
}

Best,
Jean