Re: Having trouble understanding optional and variable amount of arguments

[David Kastrup]

Stefano Troncaro <address@hidden> writes:

> First of all, I apologize for the delayed response, I wanted to write back
> earlier but I couldn't find the time to delve into your last suggestions.
> Thank you for the useful replies!
>
> @Harm
> I don't understand most of what the code you provided is doing, only that
> it works. It's far too advanced for me, so (unfortunately) dissecting it
> would require much more time than what I currently have. It looks
> interesting though, I hope I can study it in more detail later.
>
> I did manage to look a little bit into macros, and I have a question if you
> don't mind. This chapter of the guile documentation
> <https://www.gnu.org/software/guile/docs/docs-1.8/guile-ref/Syntax-Rules.html#Syntax-Rules>
> explains about define-syntax and syntax-rules. They appear to work but
> generate an error message about wrong number of arguments to a music
> function. Is that module not usable in Lilypond?

Last time I looked it broke because LilyPond uses the symbol "void" as a
music function and the 1.8 implementation is broken enough that it then
evaluates it somewhere.

I am afraid you need to stick with macros.  On the plus side, their
behavior is a lot more clear since they act only when called, not
through some pattern matching.

-- 
David Kastrup