5.6.1 Substitution function syntax

Making a function that substitutes a variable into LilyPond code is easy. The general form of these functions is

function =
#(define-music-function
     (parser location arg1 arg2 …)
     (type1? type2? …)
   #{
     …music…
   #})

where

argN

nth argument

typeN?

a scheme type predicate for which argN must return #t.

…music…

normal LilyPond input, using $ to reference arguments (eg. ‘$arg1’).

The parser and location arguments are mandatory, and are used in some advanced situations as described in the ‘Extending’ manual (see Music functions). For substitution functions, just be sure to include them.

The list of type predicates is also required. Some of the most common type predicates used in music functions are:

boolean?
cheap-list?  (use instead of ‘list?’ for faster processing)
ly:music?
markup?
number?
pair?
string?
symbol?

For a list of available type predicates, see Predefined type predicates. User-defined type predicates are also allowed.

See also

Notation Reference: Predefined type predicates.

Extending: Music functions.

Installed Files: ‘lily/music-scheme.cc’, ‘scm/c++.scm’, ‘scm/lily.scm’.


他の言語: español

LilyPond — Notation Reference