Re: building pairs in music functions

[Mattes]

Am Freitag, 13. März 2015 11:33 CET, Kevin Barry <address@hidden> schrieb:

> Dear scheme experts,
>
> I am trying to supply a constructed pair as a value for a grob property in
> a music function, but it seems no matter what I try I get an error such as:
> `warning: type check for `bracket-flare' failed; value `(num . num)' must
> be of type `pair of numbers''. A non-working example is pasted below. In
> addition to the code below, I also tried binding the variables in advance
> with let* and I tried constructing the pair with cons. I even tried binding
> a value to the constructed pair, but everything returned the same error.
> Please help!
>
> Kevin
>
> \version "2.18.2"
>
> rotateBracket =
> #(define-music-function (parser location num)
>   (number?)
>   #{
>   \once \override HorizontalBracket.bracket-flare = #'(num . num)
>   #})

Aha!
 #'(num .num)

is a shortcut for

 #(quote (num .num))

and will return a pair of _symbols_. Remove the quote and you
should be fine.

 HTH Ralf Mattes