Re: GOP2-3 - GLISS or not

[Joseph Rushton Wakeling]

Just realized I sent my original reply straight to Graham and not to the list -- 
sorry for the double email :-(

On 26/07/12 19:19, Graham Percival wrote:
> I should add some more context.  I've just remembered that we have
> a tutorial (don't ask me how I forgot), and that covers pretty
> much what I was thinking about "really simple music".

Thanks for that clarification -- it's actually a narrower subset than I thought 
you might be considering.  I do think it's very wise to exclude beaming, 
articulation and slurs/ties/phrase marks -- there are a number of potential 
syntax changes I can think of that might be useful here.

> I think we're talking about different things.  Let's put it this
> way: do you think that we'll ever move away from
>    c'4
> being a quarter note for middle C ?  That's the basic question
> here.  It doesn't matter how lilypond represents c'4 internally
> (whether it uses grobs or contexts or lilypond rationals or scheme
> rationals or bits or trits or qubits).

This is kind of the nub of the issue.  I agree that the notation for staff 
pitches (and octaves) is going to remain stable -- but I'm _not_ convinced that 
you can guarantee stability for accidentals or durations.

Briefly, Lilypond's pitch notation consists of a unique identifying string per 
pitch that mashes together staff pitch (c, d, e, f, g, a, b) with accidentals 
(s, f, qs, qf, tqs, tqf, ...), which is fine when you've got the limited pitch 
palette of semitones and quarter-tones, but starts getting out of control when 
you have more fine-grained pitch divisions, perhaps having to deal with pitch 
alterations that look something like this:

      c + 1/2 - 1/4 + 1/8 + 1/16 ....   [NOT a suggested notation!!]

... and you maybe want to put them together in fairly arbitrary combinations. It 
_might_ be possible to implement this as an additive change to the core syntax, 
but I'm not certain.

For duration, what about the proportional case, where e.g. you might want to 
specify note lengths in very arbitrary units of actual time (0.5s, 0.1s, 0.333s, 
...)?  I suspect that'd be an additive change rather than a breaking one, but 
again, I'm not sure.

> Don't get me wrong, I think it's excellent to consider future
> possibilities such as microtonal notation.  That's one of the
> reasons I think we should spend months and months discussing this,
> as well as having a huge "waiting period" before absolutely
> committing to even the most basic input.
>
> But whatever happens with contemporary notation, or gregorian
> chants, or what have you, I think that lilypond will always
> support basic classical and Romantic music, and I think that we
> can safely say "we will always support c'4 ".

Don't get me wrong either, I'm broadly confident that the core syntax you've 
identified can probably be stabilized as-is.  It's just that if you take, say, 
the collective body of music that is Gregorian, Baroque, Classical, Romantic and 
contemporary and say, "We'd like to support all the standard pitch notations 
from this literature and preferably to do it using a common style of syntax", 
I'm not 100% certain that the optimal syntax choice would be the one currently 
used by Lilypond.  Likewise for duration.  As you suggest, I think it's 
necessary and interesting to have that discussion.

The other thing I'd note is that syntax changes to this core notation are 
possibly the _easiest_ syntax changes to make, because they're almost certainly 
the easiest changes to address automatically (to change e.g. Dutch note names to 
English is a straightforward search and replace).  So in a way, this may be the 
part of Lilypond that it's least urgent to commit to stabilizing (which doesn't 
mean that it won't turn out to be stable in practice).  That's why I suggested 
doing a careful empirical study of the principal sources of syntax problems when 
trying to convert from one Lilypond version to another.