Many thanks, Aaron. A clear and helpful answer!
The “why” was simply an exercise in seeing if I could cleanup a LP file by
using such syntactic sugar (to which the answer is no :-) ).
Thanks again
..m.
> On 19 Dec 2023, at 07:05, Aaron Hill <lilyp...@hillvisions.com> wrote:
>
> On 2023-12-17 9:33 pm, Mark Probert wrote:
>> Hi.
>> I'm struggling some with writing a music function for rests. Basically I
>> want to be able to write something like
>> \rel-rest( b', 1)
>
> Minor nit: Functions in LilyPond do not use parentheses and commas for
> arguments in this way. You need only say something like the following to
> invoke your function:
>
> %%%%
> \rel-rest b' 1
> %%%%
>
>> which would place a dotted quarter rest on the indicated pitch (the
>> equivalent of
>> b'1\rest
>> I'm starting with
>> rel-rest =
>> #(define-music-function (pit dur) (ly:pitch? ly:duration?)
>> #{
>> #pit#dur\rest
>> #})
>> but that gives me an error.
>> Any suggestions?
>
> There are a few things the errors in the output log should be communicating.
>
>> Unbound variable: #{pit\#dur\\rest}#
>
> Firstly, whitespace is important in Scheme. Jamming together #pit#dur\rest
> gives the parser little hope to understand what you mean. It thinks this
> refers to a singular named thing, which in this context does not exist.
>
> So, give each part of that expression some room to breathe:
>
> ;;;;
> #pit #dur \rest
> ;;;;
>
> But then LilyPond is not satisfied that this represents a valid music
> expression. When using variables, often the number sign (#) is correct,
> however there are some spots when you need to use the dollar sign ($) instead.
>
> ;;;;
> $pit $dur \rest
> ;;;;
>
> Lastly, I am not sure why using the duration "1" as you indicated would
> result in a dotted quarter rest. Did you mean "4." or is the point of the
> music function to manipulate the inputs in some way? I am not sure I see the
> connection/logic there, so you are going to be a bit on your own there.
>
> But with the modification indicated above, you can now do this:
>
> %%%%
> { \rel-rest b' 4. }
>
> %% ...or even...
>
> { \rel-rest b'4. }
> %%%%
>
> However, this feels like more typing than just using the \rest post-event,
> apart from being prefixed.
>
>
> -- Aaron Hill
