Re: Function for /score block

[Aaron Hill]

On 2019-04-25 7:37 am, David Kastrup wrote:
> With the same interface, I'd use
> %%%%
> \version "2.19.82"
>
> Alice.Melody = \fixed f' { f4 g a bes c'1 }
> Alice.Lyrics = \lyricmode { do re mi fa sol }
>
> Bob.Melody = \fixed f' { c'4 bes d' g a1 }
> Bob.Lyrics = \lyricmode { sol fa la re mi }
>
> Global = {
>   \key f \major
>   s1*2 \bar "|."
> }
>
> makeItSo =
> #(define-music-function (label) (symbol?)
>   (let ((name (symbol->string label))
>         (value (ly:parser-lookup label)))
>    #{ <<
>        \new Staff \with {
>          instrumentName = #name
>        } <<
>          \Global
>          \new Voice = "melody" { $value . Melody }
>        >>
>        \new Lyrics \lyricsto "melody" { $value . Lyrics }
>      >> #} ))
>
> \makeItSo #'Alice
> \makeItSo #'Bob
> %%%%

That makes so much more sense.  I did not know that dotted values could 
be referenced that way, which is why I opted for the "sledge" instead of 
ly:parser-lookup.  I also had the case where the value I was 
substituting was not the top-level value, but actually the bottom-level 
in the structure.

But even with that constraint, I found the following works and avoids 
the string concatenation:

%%%%
\version "2.19.82"

Alice.Lyrics.StanzaI = \lyricmode { a b c }
Alice.Lyrics.StanzaII = \lyricmode { d e f }

Bob.Lyrics.StanzaI = \lyricmode { g h i }
Bob.Lyrics.StanzaII = \lyricmode { j k l }

foo = #(define-music-function (singer stanza) (symbol? symbol?)
  #{ \new Lyrics { $(ly:parser-lookup singer) . Lyrics . $stanza } #} )

\foo Alice StanzaI
\foo Bob StanzaII
%%%%

Curious though why in the above, I can say "Alice" in lieu of "#'Alice". 
 Is it simply because the music function's type assertion of "symbol?" 
lets the parser consume the next string as such?


-- Aaron Hill