Re: How to define functions that generate music functions?

[Carl Sorensen]

On 12/15/10 9:29 AM, "Juha Erkkila" <address@hidden> wrote:

> Is it possible to define functions that generate music functions
> in Lilypond?  I'm looking something to this effect:
> 
> -----
> \version "2.12.3"
> 
> musicA = #(define-music-function (parser location music)
>                                  (ly:music?)
>            #{ c4 d e f $music #})
> 
> \musicA { g4 a b a }
> 
> % makeMusicFn = #(define-music-function (parser location prepend-music)
> %                                       (ly:music?)
> %                 (define-music-function (parser location append-music)
> %                                        (ly:music?)
> %                  #{ $prepend-music $append-music #}))
> %
> % musicB = \makeMusicFn { c4 d e f }
> %
> % \musicB { g4 a b a }
> -----
> 
> Here expressions "\musicA { g4 a b a }" and "\musicB { g4 a b a }"
> should evaluate to same music expression, that is
> { c4 d e f g4 a b a }.  The expressions that are commented out are
> attempts to achieve what I'm looking for.  The above syntax is,
> however, wrong, as define-music-function must return a music
> expression, not a function.


Music functions must return music expressions, but scheme functions can
return functions.

Are you after this specific behavior, or some other behavior, of which this
is a simplified example?

Thanks,

Carl