\input texinfo @c -*- coding: utf-8; mode: texinfo; documentlanguage: nl -*-
@c This file is part of notation.tely
@ignore
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    When revising a translation, copy the HEAD committish of the
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@c -*- coding: utf-8; mode: texinfo; -*-
@c \version "2.12.0"
@node Interfaces for programmers
@chapter Interfaces for programmers

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@menu
* Music functions::
* Programmer interfaces::
* Building complicated functions::
* Markup programmer interface::
* Contexts for programmers::
* Scheme procedures as properties::
* Using Scheme code instead of \tweak::
* Difficult tweaks::
@end menu

@node Music functions
@section Music functions

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@menu
* Overview of music functions::
* Simple substitution functions::
* Paired substitution functions::
* Mathematics in functions::
* Void functions::
* Functions without arguments::
* Overview of available music functions::
@end menu

@node Overview of music functions
@subsection Overview of music functions

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@node Simple substitution functions
@subsection Simple substitution functions

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@node Paired substitution functions
@subsection Paired substitution functions

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@quotation
@end quotation
@node Mathematics in functions
@subsection Mathematics in functions

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@node Void functions
@subsection Void functions

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@c ode{'void} property set to @code{#t}, the parser is told to
@node Functions without arguments
@subsection Functions without arguments

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@node Overview of available music functions
@subsection Overview of available music functions

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@c fixme ; this should be move somewhere else?
@include identifiers.tely
@node Programmer interfaces
@section Programmer interfaces

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@menu
* Input variables and Scheme::
* Internal music representation::
@end menu

@node Input variables and Scheme
@subsection Input variables and Scheme

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@c ode{traLaLa}.
@c ode{\layout} block also contains a @code{traLaLa} variable, which is
@c
@c ode{\midi}, and @code{\layout} blocks are scopes nested inside that
@c ode{twice}:
@c Due to parser lookahead
@ref{Void functions}, or
@c ode{--safe} option.
@node Internal music representation
@subsection Internal music representation

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@c ode{note-event}, a @code{rhythmic-event}, and a
@c ode{melodic-event}.  All classes of music are listed in the
@c ode{duration} properties that store the pitch and duration of that
@c ode{element}.  The body of a repeat is stored in the @code{element}
@c ode{elements}.
@node Building complicated functions
@section Building complicated functions

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@menu
* Displaying music expressions::
* Music properties::
* Doubling a note with slurs (example)::
* Adding articulation to notes (example)::
@end menu

@node Displaying music expressions
@subsection Displaying music expressions

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@c index internal storage
@c index displaying music expressions
@c index internal representation, displaying
@c index displayMusic
@c ode{AbsoluteDynamicEvent} with a @code{"f"} text property.
@node Music properties
@subsection Music properties

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@c ode{'elements} property of @code{someNote}.
@c ode{\displayMusic} to display the Scheme representation of a music
@node Doubling a note with slurs (example)
@subsection Doubling a note with slurs (example)

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@c ode{'elements} property of each one, and finally make a
@c ode{SequentialMusic} with the two @code{EventChords}.
@node Adding articulation to notes (example)
@subsection Adding articulation to notes (example)

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@ref{Creating contexts}.  However, suppose that we want to write
@c ode{event-chord}.  In Scheme, the type of variable is often clear
@c ode{let} is used to declare local variables.  Here we use one local
@c ode{(ly:music-deep-copy event-chord)}.  @code{ly:music-deep-copy} is
@c ode{ly:}.  It is use to make a copy of a music
@c ode{EventChord} expression.  It is better to not modify the
@c ode{EventChord} which was given as an argument, because it may be
@c ode{NoteEventChord} expression and is a copy of @code{event-chord}.  We
@c ode{result-event-chord} expression.
@c ode{ly:music-property} is the function used to access music properties
@c ode{ArticulationEvent} expression, which we copy from the
@c ode{\displayMusic} output,
@c ode{cons} is used to add an element to a list without modifying the
@node Markup programmer interface
@section Markup programmer interface

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@menu
* Markup construction in Scheme::
* How markups work internally::
* New markup command definition::
* New markup list command definition::
@end menu

@node Markup construction in Scheme
@subsection Markup construction in Scheme

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@c index defining markup commands
@quotation
@end quotation
@c ode{markup} macro.  For example, You may use function calls inside
@c ode{markup} in order to manipulate character strings.  This is
@ref{New markup command definition}).
@c ode{#:center}, and @code{#:column} cannot be a variable or
@c ode{make-center-markup}, or @code{make-column-markup} functions
@node How markups work internally
@subsection How markups work internally

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@c ode{\raise} is actually represented by the @code{raise-markup}
@c ode{raise-markup} function is called as
@c ode{text example} string, and then it raises that Stencil by 0.5
@node New markup command definition
@subsection New markup command definition

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@c ode{#'caps} for interpreting @code{Text-in-caps}.
@c ode{padding} property) from the staff and the notes.  To make sure
@c ode{#:translate}, we add an empty string (@code{#:hspace 0}) before the
@c ode{name} is moved in relation to that empty string.  The net effect is
@c ode{(make-line-markup ...)}.  Finally, the resulting markup is passed
@c ode{props} arguments.
@ref{Text markup commands}, for details.
@c ode{define-markup-command} are limited as follows.
@c index Scheme signature
@c index signature, Scheme
@c ommand{lilypond} complains that it cannot parse @code{foo} due to its
@node New markup list command definition
@subsection New markup list command definition

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@c ode{define-markup-list-command} Scheme macro, which is similar to the
@c ode{define-markup-command} macro described in
@ref{New markup command definition}, except that where the latter returns
@c ode{paragraph} markup list command takes a markup list argument, named
@c ode{args}.  The predicate for markup lists is @code{markup-list?}.
@c ode{par-indent}, from the property list @code{props} If the property
@node Contexts for programmers
@section Contexts for programmers

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@menu
* Context evaluation::
* Running a function on all layout objects::
@end menu

@node Context evaluation
@subsection Context evaluation

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@c index calling code during interpreting
@node Running a function on all layout objects
@subsection Running a function on all layout objects

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@c index calling code on layout objects
@node Scheme procedures as properties
@section Scheme procedures as properties

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@c ode{AccidentalSuggestion},
@c ode{ly:self-alignment-interface::centered-on-x-parent} are called
@node Using Scheme code instead of \tweak
@section Using Scheme code instead of @code{\tweak}

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@c ode{^} and @code{_}.
@c ode{m} (created with @code{make-music}) are extracted with
@c ode{ly:music-property}, a new key-value pair to change the
@c ode{acons} Scheme function, and the result is finally
@c ode{let} block is the return value, @code{m} itself.
@node Difficult tweaks
@section Difficult tweaks

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@c ode{after-line-breaking} callback contains the Scheme procedure that
@c ode{my-callback}.  This procedure
@c ode{ly:hairpin::after-line-breaking} should also be called.
@c ode{\overrideProperty} function, which works similar to @code{\once
@c ode{NonMusicalPaperColumn} and @code{PaperColumn}, still works as

@c -- SKELETON FILE --