Hello,
Here is a draft doc for the #{ ... #} syntax. As I'm not exactly easy with
English, may someone read it and comment?
nicolas
--- programming-interface.itely.~1.9.~ 2004-05-13 10:36:54.000000000 +0200
+++ programming-interface.itely 2004-05-30 14:19:06.000000000 +0200
@@ -18,6 +18,7 @@
* Internal music representation::
* Extending music syntax::
* Manipulating music expressions::
+* Using LilyPond syntax inside Scheme::
@end menu
@node Input variables and Scheme
@@ -189,14 +190,24 @@
@code{\applymusic} is selected by defining
@example
- apply = #(ly:make-music-function
- (list procedure? ly:music?)
- (lambda (where func music)
- (func music)))
+ applymusic = #(ly:make-music-function
+ (list procedure? ly:music?)
+ (lambda (location func music)
+ (func music)))
[EMAIL PROTECTED] example
+
+A @code{def-music-function} macro is introduced on top of
[EMAIL PROTECTED]:make-music-function} as a syntactic suggar:
+
[EMAIL PROTECTED]
+ applymusic = #(def-music-function (location func music) (procedure? ly:music?)
+ (func music))
@end example
Examples of the use of @code{\applymusic} are in the next section.
[EMAIL PROTECTED]
[EMAIL PROTECTED]/music-functions-init.ly}.
@node Manipulating music expressions
@appendixsubsec Manipulating music expressions
@@ -289,7 +300,113 @@
@inputfileref{input/test,unfold-all-repeats.ly}, and
@inputfileref{input/test,music-box.ly}.
[EMAIL PROTECTED] Using LilyPond syntax inside Scheme
[EMAIL PROTECTED] Using LilyPond syntax inside Scheme
+
+Creating music expressions in scheme requires the knowledge of a
+little API (@code{make-music}, @code{ly:music-property}, etc), music
+expressions interfaces, how music objects are nested in order to
+build a whole music expression, and is usually verbose. For some
+simple tasks, this can be avoided, using LilyPond usual syntax inside
+scheme, thanks to the dedicated @[EMAIL PROTECTED] ... [EMAIL PROTECTED] syntax.
+
+The following two expressions give equivalent music expressions:
[EMAIL PROTECTED]
+ mynotes = @{ \override Stem #'thickness = #4
+ \notes @{ c'8 d' @} @}
+
+ #(define mynotes [EMAIL PROTECTED] \override Stem #'thickness = #4
+ \notes @{ c'8 d' @} [EMAIL PROTECTED])
[EMAIL PROTECTED] example
+
+The content of @[EMAIL PROTECTED] ... [EMAIL PROTECTED] is enclosed in an implicit
@[EMAIL PROTECTED]
+... @}} block, which is parsed. The resulting music expression, a
+SequentialMusic music object, is then returned and usable in scheme.
+
+Variables and scheme forms can be introduced in @[EMAIL PROTECTED] ... [EMAIL
PROTECTED]
+expressions thanks to the @code{$} character. This makes the creation
+of simple functions straightforward. In the following example, a
+function setting the TextScript's padding is defined:
+
[EMAIL PROTECTED],raggedright]
+ #(use-modules (ice-9 optargs))
+ #(define* (textpad padding #:optional once?)
+ (ly:export ; this is necessary for using the expression
+ ; directly inside a \notes block
+ (if once?
+ #{ \once \override TextScript #'padding = #$padding #}
+ #{ \override TextScript #'padding = #$padding #})))
+
+ \score {
+ \notes {
+ c'^"1"
+ #(textpad 3.0 #t) % only once
+ c'^"2"
+ c'^"3"
+ #(textpad 5.0)
+ c'^"4"
+ c'^"5"
+
+ }
+ }
[EMAIL PROTECTED] lilypond
+Here, the variable @code{padding} is a number; music expression
+variables may also be used in a similar fashion, as in the following
+example:
+
[EMAIL PROTECTED],raggedright]
+ #(define (with-padding padding)
+ (lambda (music)
+ #{ \override TextScript #'padding = #$padding
+ $music
+ \revert TextScript #'padding #}))
+
+ \score {
+ \notes {
+ c'^"1"
+ \applymusic #(with-padding 3)
+ { c'^"2" c'^"3"}
+ c'^"4"
+ }
+ }
[EMAIL PROTECTED] lilypond
+
+The function created by @code{(with-padding 3)} adds @code{\override} and
[EMAIL PROTECTED] statements around the music given as an argument, and returns
+this new expression. Thus, this example is equivalent to:
+
[EMAIL PROTECTED]
+ \score @{
+ \notes @{
+ c'^"1"
+ @{ \override TextScript #'padding = #3
+ @{ c'^"2" c'^"3"@}
+ \revert TextScript #'padding
+ @}
+ c'^"4"
+ @}
+ @}
[EMAIL PROTECTED] example
+
+Note: we could also have defined @code{with-padding} as a
+music function.
+
[EMAIL PROTECTED],raggedright]
+ withPadding = #(def-music-function (location padding music) (number? ly:music?)
+ #{ \override TextScript #'padding = #$padding
+ $music
+ \revert TextScript #'padding #})
+
+ \score {
+ \notes {
+ c'^"1"
+ \withPadding #3
+ { c'^"2" c'^"3"}
+ c'^"4"
+ }
+ }
[EMAIL PROTECTED] lilypond
@node Markup programmer interface
@appendixsec Markup programmer interface
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