Juha Erkkila <j...@turnipsi.no-ip.org> writes:
> Howdy,
>
> I had some lilypond code that worked in 2.12 versions, but appears
> broken in 2.14. I had used a construction in which a music function
> calls itself. Here's an example:
>
> ----------------------------------------------------------------------
> tags = #(define-music-function (parser location tags music)
> (list? ly:music?)
> (cond ((null? tags) music)
> (else (let ((firsttag (car tags))
> (othertags (cdr tags)))
> #{ \tags $othertags \tag $firsttag $music #}))))
>
> foo = \tag #'a \tag #'b { c4 d e f }
> bar = \tags #'(a b) { c4 d e f }
>
> \score {
> {
> \keepWithTag #'a \foo
> \keepWithTag #'b \foo
>
> \keepWithTag #'a \bar
> \keepWithTag #'b \bar
> }
> }
> ----------------------------------------------------------------------
>
> The point here is that both \foo and \bar should give equivalent
> results when used with \keepWithTag. The function \tags takes
> a list of tags and applies them to a music expression.
>
> With 2.12 this used to work (I don't have one to test here with,
> but I'm quite sure), but with 2.14.2 I get this:
> <string>:1:39: error: syntax error, unexpected MARKUPLINES_IDENTIFIER
> parseStringResult = \notemode { \tags
> \lilyvartmpbg \tag \lilyvartmpbh
> \lilyvartmpbi }foo.ly:12:2: error: errors found, ignoring music expression
>
> {
> foo.ly:0: warning: no \version statement found, please add
> Perhaps some definition in straight scheme might also work here?
> Any ideas?
The problem here is that you are writing $othertags. This tells
Lilypond that it should figure out on its own what syntactic type
$othertags should receive. An empty list meets the markup-list?
predicate, so Lilypond decides to consider this a markup list
syntactically. Which is not compatible with the list? predicate, since
that is looking for a Scheme expression (or a simple string)
syntactically.
So just writing #$othertags should put Lilypond on the right track and
keep it from guessing the syntactical class wrong here.
markups and markup lists are somewhat peculiar: most other Lilypond data
structures don't rely on an inner analysis for figuring out their type.
That an empty list is classified as "markup-list?" is a bit
disconcerting in this context. I don't have a good idea how to do this
better.
You'll have the same problem when writing
icky = #'()
After that, concerning Lilypond \icky is a markup list and nothing else.
--
David Kastrup
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