Graham Percival <gra...@percival-music.ca> writes:
> On Wed, Oct 12, 2011 at 05:42:47PM +0200, David Kastrup wrote:
>>
>> I am currently trying to make music functions more powerful, in
>> particular their argument predicates. Also I am trying to relieve the
>> parser from responsibilities.
>
> Looks basically good to me. GLISS was never planned to tackle
> scheme stuff, and waiting for GLISS 2 would take 2 years or more
> at our current rate of progress. I see no reason to postpone this
> change for that long.
>
>> Now I have a possibly slightly contentious change... I want to let { }
>> mimic the new functionality of #{ #} instead of creating sequential
>> music unconditionally. That means the following:
>>
>> previously equivalent to now equivalent to
>> { \with ... } syntax error context-modification
>> { c4 } \sequential { c4 } simple-music
>
> What happens if somebody writes
> { \with foo c4 \with bar d4 }
> ?
Good catch. I don't think we want anything but a syntax error here.
One approach would be not to ignore Scheme expressions in a sequence
unless they evaluate to "unspecified" or at least a limited set of
"ignorable" values.
More compatible would be the approach that you can omit braces only when
a certain construct is syntactically expected somewhere: if it is to be
produced "foreignly", use # or { ... }. Then
{ { \with foo } c4 { \with bar } d4 }
would be a music sequence with two Scheme expressions inside getting
ignored, and { \with foo c4 \with bar d4 } would be a syntax error.
--
David Kastrup
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