Hi,
After struggling with understanding Lilypond/Scheme's predicative
types, of which I found basically no documentation other than a list
of them with a minimal description here
http://lilypond.org/doc/v2.20/Documentation/notation/predefined-type-predicates,
I would like to ask what type of predicatives the \tempo function
accepts. When you write \tempo 4 = 56, what does "4 = 56" for Scheme
mean? This is of course something that I'm not using in my script yet,
but knowing this might let me extend the script, namely that its usage
accepts a proper tempo definition, so that (maybe with a more elegant
syntax that doesn't use "" for each argument) I can also use that same
number to give to an omitted tempo marking for MIDI playback.
I'm sure more knowledgeable people will be able to provide more
insightful answers, but for what it's worth: Looking at lily/parser.yy,
I see
tempo_event:
TEMPO steno_duration '=' tempo_range {
$$ = MAKE_SYNTAX (tempo, @$, SCM_EOL, $2, $4);
}
| TEMPO text steno_duration '=' tempo_range {
$$ = MAKE_SYNTAX (tempo, @$, $2, $3, $5);
}
| TEMPO text {
$$ = MAKE_SYNTAX (tempo, @$, $2);
} %prec ':'
;
which I take to mean: The three forms
* \tempo 4 = 96
* \tempo Crazy 4 = 260-270
* \tempo "Sluggishly slow"
are hardcoded as variants into the parser. My guess is that this might
be hard (or impossible) to accomplish in a music function.
Best
Lukas
