Re: [GLISS] why the hell all this fuss

[Janek Warchoł]

On Fri, Sep 7, 2012 at 9:42 AM, David Kastrup <address@hidden> wrote:
> Janek Warchoł <address@hidden> writes:
>
>> On Thu, Sep 6, 2012 at 9:55 AM, David Kastrup <address@hidden> wrote:
>>> I don't see why you should not be able to do this using music functions.
>>
>> Hmm.  You may be absolutely right.  Maybe all we need is to write such
>> functions and ship them with LilyPond!
>
> at =
> #(define-music-function (parser location t e m)
>   (ly:duration? ly:event? ly:music?)
>   #{ << #m { \skip $t <>$e } >> #})
>
> \new Voice {
>   \at 1*1/3 \p
>   \at 1*2/3 \<
>   \at 1\!
>   c'1
> }

Thanks!  This shows how much i have to learn - didn't think it would be so easy.
However, i see two problems with this function, and i suppose they're
not easy to fix within current framework:
1) it is "prefix".  I'm pretty sure that users will get confused as to
why sometimes you write \p after a note, and sometimes before it. (of
course if you understand what the function actually does, everything
becomes clear - but i think it's important to have syntax that looks
consistent and intuitive without reading function definitions (is the
word "transparency" appropriate here?))
2) similarly to using << >> construct manually, it breaks
full-measure-extra-space - compare spacing of the whole notes:

\paper { ragged-right = ##f }

at =
#(define-music-function (parser location t e m)
  (ly:duration? ly:event? ly:music?)
  #{ << #m { \skip $t <>$e } >> #})

\new Voice {
  b8 b b b b b b b
  c'1
  b8 b b b b\< b b b
  \at 2 \! c'1
}

Now, full-measure-extra-space isn't that important, but we may expect
that other similar context-specific things will appear and break
because of spacer rests used in \at.

> What we have under the umbrella of "syntax discussion"
> contains three things: lexical units, grammar and vocabulary, mostly
> implemented in lexer.ll, parser.yy, and *.ly respectively.  In order to
> keep syntax predictable, we want to be able to solve most problems just
> by extending the vocabulary.  That means that lexical units and grammar
> should be as generic, powerful, and simple as possible.

Agreed.

> Specialized
> lexical modes take power from the vocabulary.  We want to avoid them as
> much as possible given our historic constraints.

ok.

>>>> My rough idea would look something like this
>>>> (this is just a musing, not a proposal for discussion yet):
>>>>
>>>> { b2 \<@0.5 a2 address@hidden } meaning { << b1 { s2 \< s2 \! } >> }
>>>
>>> Looks like a case of the cure being worse than the problem.  Apart from
>>> not being related in any obvious manner.
>>
>> I'm not sure i understand what you had in mind.
>
> I wanted to express that I'm not sure I understand what you had in
> mind.  I can't figure out how your proposed syntax is going to mean what
> you state it would.  Durations are different, there is a different
> number of notes...

ooops!  That's embarassing!  I've mixed two different examples from my vault.
I intended to write this:
  { b2 \<@0.5 a2 address@hidden } meaning { << { b2 a2 } {  s4 s2 \< s4 \! } >> 
}
(i don't insist on having decimal numbers.  It's just that the idea
was not to specify a delay duration, but a percent of the "parent"
note duration, and decimal numbers look better for this)

cheers,
Janek