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
(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 $ (in places where only
Lilypond constructs are allowed) or # (to use it as a Scheme
value or music function argument or music inside of music lists) to
reference arguments
(eg. ‘#arg1’). |
The list of type predicates is required. Some of the most common type predicates used in music functions are:
boolean? cheap-list? (use instead of ‘list?’ for faster processing) ly:duration? ly:music? ly:pitch? markup? number? pair? string? symbol?
For a list of available type predicates, see Tipi di predicati predefiniti. User-defined type predicates are also allowed.
Vedi anche
Guida alla notazione: Tipi di predicati predefiniti.
Estendere LilyPond: Music functions.
File installati: ‘lily/music-scheme.cc’, ‘scm/c++.scm’, ‘scm/lily.scm’.
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