[lilypond.git] / Documentation / tex / tutorial.yo

COMMENT(-*-text-*-)

redef(var)(1)(whenlatex(latexcommand({\normalfont\scshape )ARG1+latexcommand(}))\
    whenhtml(sc(ARG1)))

COMMENT( This document contains Mudela fragments.  You need at least
Yodl-1.30.18 to convert this to tex or html.

TODO

need to rethink paper size stuff?

pipethrough(date) sucks.

paragraphs have too much space.

in stead <-> instead
)

COMMENT(
        Mainly written by Han-Wen Nienhuys, 

        with help of (among others)

        * Jan Nieuwenhuizen

        * Lambert Meertens,

        * Adrian Mariano

        * Mats Bengtsson

)

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    \textheight 53\baselineskip
    \advance\textheight by \topskip
    \marginparwidth 1 in        %   Width of marginal notes.
    \oddsidemargin 0.25 in      %   Note that \oddsidemargin = \evensidemargin
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    \textwidth 5.875 in % Width of text line.
    \input mudela-book
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article(Mudela, the Music-Definition Language)
      (Han-Wen Nienhuys and Jan Nieuwenhuizen)
      (nop()PIPETHROUGH(date "+%B %d, %Y")()()nop())


latexcommand(\def\interexample{})
latexcommand(\def\preexample{\par})
latexcommand(\def\postexample{\par\medskip})
latexcommand(\def\file#1{{code(#1)}})

COMMENT(urg, texinfo include breaks)
whenhtml(
includefile(html-disclaimer.yo-urg)
)

sect(Introduction)
label(tutorial:introduction)
latexcommand(\parindent2pc)
  
If you are reading this, you probably are interested in printing
music.  LilyPond is a program that can print music from a
specification that you, the user, supply.  Using LilyPond may be a bit
quaint in the beginning, because you have to give that specification
using a em(language).  That might not be what you expect if you are
familiar with graphical interfaces.  But there are some big
advantages: first, once you master the language, entering music can be
done quite efficiently.  Secondly, it is possible to explain exactly
what the meaning of a language is, i.e., the semantics are much
clearer.  Thirdly, since the program is not interactive, no tradeoffs
have to be made between processing speed and beauty of the output.

This chapter is a gentle introduction to Mudela, the language that
instructs LilyPond to typeset music.  We will explain Mudela by
presenting a series of examples of Mudela input.  The corresponding
output will be shown on the right or below, just as it was produced by
LilyPond.

We will assume that you more or less understand the basics of music notation.  
If you are not familiar with the English terms for music notation, you 
should consult bind(Appendix)ref(glossary): it contains a glossary 
of musical terms along with translations in some other languages.

If you want to try the examples given here, you should have a 
look at bind(Section)ref(sec:running-lilypond) first.

sect(Music copying, music definition and music entry)
label(tutorial:copying-vs-def-vs-entry)

If you have copied music before, using LilyPond may seem awkward
to you in the beginning.  The purpose of LilyPond informally is
explained by the term `music typesetter'.

This may give the impression that the program is like a drawing tool
and that it lets you control precisely how the music is formatted.
This is not the case: not only does the program print musical symbols,
LilyPond also tries to make esthetic decisions---to be precise, we
programmed her to do what we find nop(pretty.)footnote(We formed our
taste by looking at, and reading all about fine music engraving.  Of
course, our taste is also bound by all the accepted rules of common
music notation.)  You do not have complete control over what is
happening.  Usually that is not a big loss, since good engraving is a
very complex trade. In other words, you don't have control, so you do
not have to worry about what is happening precisely.

Secondly, we expect you to enter the meaning of the music, not the
sheet music itself.  The input to LilyPond is a music definition,
which is something different than notation: notation is a graphical
system.  Put more concretely: your input to LilyPond should contain
information like ``a dotted quarter note, pitch nop(d)sups(2).''
LilyPond will figure out from the musical information that a black
note head with a stem but without flag, fourth staff line, with dot
should be printed.

When you are copying music by hand from a printed score, you don't have 
to know what the score means; you just copy the symbols.  With LilyPond 
such a thing is not possible.  You have to enter the meaning of the 
symbols, and this might not always be as easy.  On the other hand, once 
entered, any piece of music can be played and transposed automatically.

Finally, in some spots we will cheat a bit when it comes to musical
definition.  Mudela has some entry modes that help to make typing
Mudela pleasant.  For example, the phrase ``a dotted quarter note,
pitch nop(d)sups(2)'' translates to the following longhand:
verb(
\musicalpitch { 1 2 0 } \duration { 2 1 })

This data is what we consider the musical em(definition).  Mudela
has a special entry mode where you can conveniently abbreviate this to
`code(d''4.)'.  There are some features that also make the quotes and
numbers in `code(d''4.)'  superfluous in some cases.

For those who are curious, the numbers in
`code(\musicalpitch { 1 2 0 })'
example mean octave, notename, and accidental respectively.  The
numbers in `code(\duration { 2 1 })' are the (negative) logarithm of the
duration (2 is a quarter note, 3 is an eighth note, etc.) and the number
of augmention dots respectively.

sect(When you know the notes to nop(print)ellipsis())

The basic building block of music is the note.  You can have LilyPond
print a note by specifying its pitch and duration.  The pitch of the
central C is written as code(c').  This is in line with musicological
notation; there this pitch is transcribed as nop(c)sups(1) or c'.  A
quarter-note duration is written as code(4).  So, to print a quarter
note whose pitch is central C, you enter the following:
mudela(fragment,verbatim,center)( c'4 )


subsect(Duration)

The duration of a note is specified as a number: a whole note is
denoted by 1, a half note by 2, a quarter by 4, and so on.  If you
want to augment a duration with a dot, simply affix a period to the
number.  Here are some random notes to show how it works.

mudela(fragment,verbatim)(
  c'1 c'2 c'4 c'8 c'16 c'32 c'64 c'64 c'2. c'8. c'16
)

subsect(Basic pitches)

The pitch code(c') actually consists of two parts: one part for the
note name, and one for the octave.  The letter specifies which note
name to use: note names simply are the letters code(a) to code(g).
The number of apostrophes specifies the octave to use: the central C
is denoted by code(c').footnote(By convention, the A above central C
at concert pitch is the tone that is used to tune instruments.  Its
frequency is about 440 Hz.)  The C which is an eighth higher (the C in
the ``two-line octave'') is denoted by code(c''): every octave adds a
quote.  A note name without quotes designates the pitch below code(c')
(the C in the ``small octave''). If you want to go down even further,
commas should be added, e.g., the C in the ``contra octave'' is
expressed as code(c,,).footnote(The comma is meant to represent a
sunken apostrophe.)


This example demonstrates octaves:
mudela(fragment,verbatim,center)(
   c,,4 c,4 c4 c'4 c''4 c'''4
)

And this example demonstrates notenames:
mudela(center,fragment,verbatim)(
  c'4 d'4 e'4 f'4 g'4 a'4 b'4 c''4
)

A rest can be entered as a note with the special name code(r), e.g.,
mudela(fragment,verbatim,center)(r4)

This already gives us enough material to make simple songs. In
bind(Figure)ref(fig:twinkle1) a portion of the traditional song
``Twinkle Twinkle Little Star'' is shown.

latexcommand(\begin{figure}[h])
  center(
mudela(fragment,verbatim)(
        c''4 c''4 g''4 g''4
        a''4 a''4 g''2
)
    latexcommand(\caption{Twinkle twinkle little star (version 1)})
    label(fig:twinkle1)
  )
latexcommand(\end{figure})


subsect(Alterations)

We have so far ignored chromatically altered pitches.  The names `a'
to `g' for entering pitches are convenient: they are short,
pronounceable and they resemble the words for pitches in normal
musical vocabulary.

Enter flats and sharps.  In English there is no standard terse word
for C sharp or C flat.  For this reason, we implemented a different,
non-English convention for entering altered pitches: a note is made
sharp by adding the suffix `--is' to its name, and flat by adding the
suffix `--es'.  For a double sharp another `--is' suffix is added, for
flats another `--es' suffix. The names for the alterations of C are
given in bind(Table)ref(notename-tab).

latexcommand(\begin{table}[h])
  center(
    table(2)(ll)(
      row(cell(english)cell(LilyPond))
      rowline()
      row(cell(c double flat)cell(ceses))
      row(cell(c flat)cell(ces))
      row(cell(c natural)cell(c))
      row(cell(c sharp)cell(cis))
      row(cell(c double sharp)cell(cisis))
    )
  )
  latexcommand(\caption{Default note names})
  label(notename-tab)
latexcommand(\end{table})

Variations on this convention are used in a number of germanic
languages, notably Dutch, German, Swedish, and Norwegian.  To be
precise, LilyPond actually defaults to Dutch notenames, with
code(aes), code(aeses), code(ees) and code(eeses) added for
consistency.

Throughout this document we will continue to use the Dutch names.  To make
(Dutch) pronunciation easier, the a-flat and e-flat are contracted to
code(as) and code(es).  Similarly, the a double flat and e double flat are
contracted to code(ases) and code(eses).

If you are not comfortable with these names, you can make your own.
Note names for different languages are included with the example
initialisation files, amongst others English (C sharp is abbreviated
to code(cs)), Italian, Swedish and Norwegian.  If you want to use
these names, you should look at bind(Section)ref(subsect:include) for
information on how to use include files.

sect(Running LilyPond)
label(sec:running-lilypond)

In the previous section some basic elements of Mudela were presented.
We didn't want to bore you too much with repetitive details, so we
left out some red tape that's needed for a  of Mudela in a form that is accepted
by LilyPond.  To
be precise, we wrote code(X Y Z), when we really meant
verb(\score {
   \notes { X Y Z }
   \paper {}
})
We will continue to leave out the red tape this, until the time is right to explain what 
it means.


Because LilyPond uses a language, it  is a so called em(batch)
program.
This means, that you use a
text editor (such as code(emacs) or code(vi)) to create an input
file.  When you are done editing your input file, you save it, and you
run LilyPond on the file.  If LilyPond finds any errors in your input file
then nop(she)footnote(We're sure that if computer programs could have
  gender, LilyPond would be a female computer program.  So we will
  refer to the program as a she. This gender-bending is not to tease
  you, dear reader.  We do it in real life as well. In the past two
  years LilyPond has become sort of a baby daughter to us, keeping us
  awake at night, but also providing us with lots of joy.  We hope you do
  not mind our little aberration from the traditions of computer-manual
  writing.) COMMENT( 
 The name LilyPond is actually sort of a girl's name.  Can you guess which
 one ?)
will complain.  If everything went well, then she'll generate a file, that
you can process further to view or print.

Using LilyPond to print or view some music is a four-step procedure.
To get you started we'll run down the full procedure for you.

enumerate(
it()
Fire up your favourite editor (if you don't
know any editors, try code(joe silly.ly)),
and key in the example from bind(Figure)ref(fig:twinkle1), with red tape:
verb(
\score {
        \notes {
          c''4 c''4 g''4 g''4
          a''4 a''4 g''2
        }
        \paper {}
}
)

Save your file as file(twinkle.ly).footnote(The default extension for Mudela
files is file(.ly).)

it()
Run LilyPond on your newly created file: enter code(lilypond twinkle).
LilyPond will then print all kinds of mumbo jumbo that can safely be
ignored.  You might see something like this:
verb(
GNU LilyPond 0.1.55/FlowerLib 1.1.39
Parsing ... [/home/hanwen/musix/spacer/init/lily-init.ly[/home/hanwen/

        ... stuff left out here ...

                              ]  Documentation/twinkle.ly]
Interpreting music ...[1] (time: 0.04 seconds)
Preprocessing elements... 
Calculating column positions ... [2]
Approximated: 1 lines, (with an average of 4.0 columns)
Time: 0.01 seconds
warning: Can not solve this casting problem exactly; revert to Word_wrap
[2]Time: 0.00 seconds

Postprocessing elements...
TeX output to twinkle.tex ...
)

All has gone well; there were some warnings but no errors.  The run
resulted in output, a TeX file called file(twinkle.tex).

file(TeX) is usually spelled TeX().  It is a batch program for
typesetting text. It was developed by the great programmer and
scientist Donald Knuth to typeset his famous bookseries em(The Art of
Computer Programming).  As you can see, TeX() can be adapted to do a
lot more.  whenlatex(In fact, the document that you are reading now was also
produced with TeX().) COMMENT(ugh.)


it()
  To do something useful with the output you have to run TeX() on it
  first.  Run the command code(tex twinkle).  The output should resemble this:
verb(
This is TeX, Version 3.14159 (C version 6.1)
(twinkle.tex
Babel <v3.6h> and hyphenation patterns for american, dutch, loaded.
(/home/hanwen/lib/texmf/tex/lilypond/lilyponddefs.tex
(/home/hanwen/lib/texmf/tex/lilypond/dyndefs.tex)
(/home/hanwen/lib/texmf/tex/lilypond/fetdefs.tex
(/home/hanwen/lib/texmf/tex/lilypond/feta20.tex)
(/home/hanwen/lib/texmf/tex/lilypond/lily-ps-defs.tex))) [1] )
Output written on twinkle.dvi (1 page, 3084 bytes).
Transcript written on twinkle.log.
)
  The human translation is ``everything went OK, the result is one
  page long, and I put it in file(twinkle.dvi).''

it()The file(twinkle.dvi) file is a description of how a piece of
text looks when it is printed.  You can view it, or print it.  If you
are using a Unix system equipped with X-Windows, then you can issue
the command file(xdvi twinkle) to view the result.  If this is not the
case, consult your local TeX() guru on printing and viewing DVI files.
What is in your window should approximately look like this:
mudela()(
\score {
        \notes {
          c''4 c''4 g''4 g''4
          a''4 a''4 g''2
        }
        \paper { linewidth = 13.\cm; }
}
)

it()
If you want to print file(twinkle.dvi), you should invoke the command
code(dvips twinkle).  Running this command should generate a
PostScript file called file(twinkle.ps).  This file can be printed on
any PostScript compatible printer.  You should not use any other
tools: the output from LilyPond contains fragments of PostScript which
will not print correctly if you don't use PostScript.  If your printer
doesn't understand PostScript, you should check out GhostScript, a
PostScript emulator.
)



The four-pass procedure sketched above is a bit clumsy.  Moreover, the
result is pretty crude: the page does not include prettily printed
titles and if you are unlucky, the margins don't come out well.  Jan
Arne Fagertun wrote a tool to take the above steps out of your hands,
make neat margins and print titling.  The tool is called file(ly2dvi),
and it should be on your system if you use Lily on a Unix platform.
If you use file(ly2dvi), then you can do verb(ly2dvi twinkle.ly ) in
stead of steps 2 and 3.  You will feel the real advantage of using
file(ly2dvi) when you add titling to the music.  This is something
that we will discuss in bind(Section)ref(tutorial:titling).


COMMENT(This document does not cover all of Mudela.  Due to technical details,
the precise working of Mudela is coupled to the innards of LilyPond.
If you really want to know all the details, your best bet would be to
get the sources to LilyPond and read the parser and scanner source.
They are in file(lilypond-x.y.z/lily/parser.yy) and
file(lilypond-x.y.z/lily/lexer.ll).)



sect(Chords)

Up till now we have only considered music that was rather simple.  All
the music had notes going in one direction, from left to right, one
note following the other.  You might be wondering if this is all Lily
can do, or whether it is possible to stack notes as well (creating
em(chords)).  Rest assured: we designed LilyPond while keeping in mind
that she must be able to handle any notation construct that can be
expressed conveniently.  Of course we did not leave out chords.

In Mudela you can form a chord of several notes by enclosing them in
pointed parentheses, bind(i.e.)bind(langle())bind(and)rangle().  ASCII
doesn't really have these delimiters, so Mudela uses the larger-than
(code(>)) and smaller-than (code(<)) signs instead.  For example, a
D-major nop(chord)footnote(Recall what was said in the previous
section about flats and sharps: the word code(fis) means an f sharp.)
can be described by the following fragment:
mudela(fragment,verbatim,center)(
  <d'8  fis'8 a'8 d''8>
)

  Chords can be entered in the music in the same places that notes
can.  As an example we give a snippet of ``Twinkle Twinkle Little
Star'' in chords.  The chords may seem, slightly unconventional, but they
only serve to show how chords work.  We've aligned the chords
in the input on their starting beat just to help you reading it.
This layout does not influence the typesetting result in any way.

mudela(verbatim, fragment)(
  c''4             c''4              <c''4 g''4>       <c''4 e''4 g''4>
  <c''4 e''4 a''4> <b'4 d''4 a''4>   <b'2 d''2 g''2>
  <a'4 d''4 f''4>  <bes'4 d''4 f''4> <bes'4 c''4 e''4> <g'4 c''4 e''4>
  <e'4 a'4 d''4>   <a4 g'4 cis''4>   <d'2 f'2 d''2>
)



sect(Shortcuts for duration)

If you typed the last example into a Mudela file, you will have
noticed that the input has lots of repetitions.  You will probably
have made some errors with the right durations and number of
octavation quotes.
To save keystrokes and prevent errors Mudela
has some handy shortcuts.  The simplest is the shortcut for
durations.  You don't have to type the duration if it
is the same as the last duration entered.  This saves a considerable
number of keystrokes, and thus reduces the potential for errors.  The
previous example can be reduced to verb(
  c''4          c''            <c'' g''>        <c'' e'' g''>
  <c'' e'' a''> <b' d'' a''>   <b'2 d'' g''>
  <a'4 d'' f''> <bes' d'' f''> <bes' c'' e''> <g' c'' e''>
  <e' a' d''>   <a g' cis''>   <d'2 f' d''>
)


If you entered this, you probably made some little errors with the
right amount of quotes as well.  To remedy this, mudela has another
feature called `relative octaves', which reduces the number of quotes
needed.  If you want to enter large pieces of music em(now) we
recommend you make an excursion to
bind(Section)ref(sec:relativeoctaves) and learn about relative
octaves.



sect(Comments)

If you want to make some private notes about the Mudela code that you
entered, you can do so by inserting comments into your file.  The
contents of these comments are ignored by LilyPond.  Mudela has two  comment
styles: line comments and block comments.  The line comment
is introduced by the percent sign:
verb(
  c''4
  c''4   % shouldn't this be a different pitch?
)

Block comments are enclosed in code(%{) and code(%}).

verb(
  c''4
        %{
        Ludwig van Bavaria's  original manuscript has an fffff dynamic sign.  
        Clearly one can see the onset of paranoid schizophrenia in the
        composer from these subtle nuances in his writings.
        %}
  c''4 
)


sect(Adding nuances: articulation and dynamics)

Having just chords and notes does not give you real music.  Real music
has more liveliness to it: music can have articulation, dynamics
(louder and softer), etc.  This liveliness has notation, so LilyPond
can print it.  We'll start out by explaining how to obtain the
smallest grains of nuance: the articulation of a single note.  Articulation
is entered by writing a dash and the name of the desired articulation
mark.  You have to add a backslash in front of the name to distinguish
it from the name of a note.  mudela(fragment,verbatim)(
  c''4-\staccato
  c''4-\tenuto )

Typing a lot of staccato notes in this syntax will get tedious very
quickly.  Therefore, Mudela has some handy abbreviations for
articulation marks such as staccato and tenuto.  They are shown in the
following example:

mudela()(
\score{ \notes {
        \property Voice.textstyle = typewriter
        c''4-._"c''4-." s4
        c''4--_"c''4--"  s4
        c''4-+_"c''4-+" s4
        c''4-|_"c''4-|" s4
        c''4->_"c''4->"  s4
        c''4-^_"c''4-\\^{ }"  s4 }
        \paper { linewidth = 12.\cm; }})



Text and digits for fingering can be entered in the same manner: add a
dash and the text or digit to be printed:
mudela(fragment,verbatim)(
  c''4-1 g''4-5 c''-"Sul tasto" )
Currently, the meaning of the
syntax `note-dash-digit/articulation/text' is just ``add a superscript to this
note.''  This is not in line with our goal to em(define) music with
Mudela.  We hope that this will be fixed in a future version of the
language.  In the meantime you can abuse this: the super- and
subscripts can be forced into up or down position respectively by entering an
a caret (code(^)) or an underscore, code(_) instead of the dash:
mudela(fragment,verbatim,center)(
  c'4-^ c'4^^ c'''4-^ c'''4_^
)

Dynamic markings are another way to add a nuance to a note.  They are
entered by adding the name for the dynamic sign after the note.  You
should not enter a dash between the name and the note.footnote(This
  is inconsistent.  We hope that this will be fixed in a later
  version of the language.)
mudela(verbatim,fragment)(
  c4 \ff c4 \fp c4 c4 \ppp c4 c4 \sfz
)
COMMENT(UGH)

sect(Bridging the notes: beams, slurs and ties)

Up till now most of the typesetting concerned simple fixed symbols
only.  Now we turn to variable symbols: symbols that run from one note
to another. In LilyPond terminology, such a symbol is called a
em(spanner).  To print a spanner, you have to attach a marker to the
note that begins it and to the one that ends it.


The first example of such a symbol is the slur.  For the slur, the
start marker is the opening parenthesis. It won't be a surprise that
the stopping marker is the closing parenthesis.
For example:
mudela(fragment,center,verbatim)( c'4( )c'4 )

otice that the parentheses should be between the notes.footnote(The
location of the parentheses might be changed in a future version of
the language.)

It is your job to make sure that each slur that you start also ends.
If it doesn't end, then Bad Things are likely to happen.  The slur is
quite flexible: you can nest nop(slurs,)footnote(This is inconsistent when
compared to the syntax for articulation hints.  This will probably be
fixed soon.) and you can connect a note with a slur on both the left and the
right side:

mudela(fragment,verbatim,center)(
  c'4((   )c''4 )c'4( )g'4 
)

Another spanner is the beam (see bind(Figure)ref(mud:beam)).  It
indicates the duration of the connected notes, and thus it acts like an
extended version of the flag.  Secondly, the pattern of
left/right-pointing beams hints at the metric structure of the
measure.


latexcommand(\begin{figure}[h])
  center(
    mudela(fragment)([c'8 c'8] [c'16 c'16 c'16 c'16] [c'16. c'32 c'32 c'16.] )
    latexcommand(\caption{Some beams})
    label(mud:beam)
  )
latexcommand(\end{figure})


Strictly speaking, a beam is not a musical concept.  The pattern of a
beam can be derived from the structure of the time signature and the durations
of the notes. It is merely a device that helps you understand the
rhythms notated. Unfortunately, LilyPond is not smart enough to insert
beams into your music on her own. You will have to instruct her by
marking the starting and stopping point of the beam with `code([)' and
`code(])' respectively, e.g.

mudela(fragment,verbatim,center)(
  [g'8 g'8]
)

LilyPond has code that guesses what the pattern should look like, so
that you don't have to specify the beaming for complicated
patterns.footnote(Unfortunately the algorithm used is not foolproof yet:
  code([c8. c32 c32]) will produce incorrect results.)

Again, it is your responsibility to make sure that you end every beam
that you start.

A third spanner is similar to the slur: the tie.  The tie looks like a
slur, but a slur connects whole chords, whereas the tie connects
note heads.  Tied notes should be played as one long note.
In analogy with TeX()'s tie (which  ties together words with a
space), LilyPond's tie is entered as a tilde, ~.  
mudela(verbatim,center,fragment)(c''1 ~ c''4)

The input convention for the tilde is somewhat peculiar when used in
conjunction with chords.  Internally, the extra information that is
represented by the tilde has to be attached to a note (or to a rest,
for that matter).  For this reason, you can't put the tilde between
two chords (as in code( <c' g'> ~ <c' g'>)).  The tilde sign must be
directly after a note of the chords.  It does not matter which
one. The following example demonstrates this:
mudela(fragment,verbatim,center)(
  <c'1 ~  g' es''> <c'4 g' es''> 
)

sect(Commands)
label(sec:commands)

Up till now, we only printed notes, and correspondingly only entered
notes. But notation contains many other constructs, constructs that
help you with reading those notes.  Examples of such constructs are
clefs, time signatures, keys etc.

If you look carefully at the example in
bind(Figure)ref(fig:twinkle1), you will notice that the output
includes some bar lines and clefs, and that there are no references to
those in the input.  They were generated automatically.

Not all such hints can be inserted automatically, and you can also
override some of the settings.  This can be done by inserting various
commands between the music.  The general form of these commands is
center(
  em(keyword) sc(arguments)
)

em(keyword)s are words that have a special meaning to the parser of
Mudela.  Because the parser must be able to distinguish the keywords
from note names, they have to be preceded by a so-called escape
character, the backslash, `code(\)'.  To separate the arguments from
any notes that might follow the arguments, you have to end your
command with a semicolon.  An added benefit of this construction is
that the commands stand out between your notes, because of the
backslashes.

So the general form actually is `code(\keyword argument argument ... ;)'
Let us review these commands:

description(
dit(code(\clef) var(clefname)) This command sets the current clef for notation,
  i.e., a clef symbol is printed and the notes following this command
  are shifted vertically.  The argument is a string, the name of the
  new clef. The default clef is the treble clef.
  mudela(fragment,verbatim)(
    \clef "bass"; c'4
    \clef "treble"; c'4
    \clef "alto"; c'4    
  )
dit(code(\key) var(pitch)) This command changes the current key signature.  The
  key signature is printed at the start of every line. The identifiers
  code(\major) and code(\minor) can be used to decide if all the 
  subsequent code(\key) commands are major or minor, respectively. 
  The default is major keys. The key of C-minor can 
  thus be specified as `code(\key es)' or `code(\minor \key c)'.
  
dit(code(\keysignature) var(pitchlist))

This command changes the current key signature.  Unlike the
`code(\key)' command, this command can produce arbitrary key
signatures, which can be useful for unconventional keys or modes.  The
key signature is given in the form of a list of notes.  The notes will
be printed in the key signature in the order that they appear on the list.
For example, the key
of C-minor can be specified as `code(\keysignature bes es as)'.  The
command `code(\keysignature fis es bis)' provides a more exotic
example.


dit(code(\time) var(numerator)code(/)var(denominator))
  This command changes the current time signature.  LilyPond uses the
  time signature to
  calculate where to place the bars that start a measure.  These bars
  in turn are the places where a system can be broken into lines.

  The default value for this time signature is common time (4/4).  You
  can also tell this from the  Twinkle ``Twinkle Little
Star'' example in bind(Figure)ref(fig:twinkle1).  This
song actually has a 2/4 time signature, so a metrically more correct
  version  would start with as follows:
  mudela(fragment,center,verbatim)(
    \time 2/4;  c'4 c'  g' g' 
  )


dit(code(\cadenza) var(togglevalue)) When typesetting music without a
regular meter (such as an ad libitum cadenza), no bar lines should be
printed.  In LilyPond you can achieve this by issuing the command
`code(\cadenza 1)': it turns off the automatically
generated bar lines.

You switch them on again with `code(\cadenza 0)', and then a bar line
is printed.  LilyPond will act as if you are again at the start of a
measure.

dit(code(\bar) var(bartype))
  This command lets you print special bar
  lines and repeat symbols.  You can also use it to allow line breaks
  when entering cadenzas.  The argument var(bartype) is a string that
  describes what kind of bar line to print.

mudela(fragment,verbatim)(
    \bar "|:"; c'4 \bar ":|:";    c'4  \bar ":|";  c'4 \bar "||";
    c'4 \bar "empty"; c'4 \bar "|.";
)
  The command `code(\bar "empty")' does not create any visible bar
  line, but it does tells LilyPond to allow a linebreak
  at that position.  The `code(\bar)' command prints the specified
  symbol immediately.  If you give a `code(\bar)' command at the end
  of a measure then
  the specified symbol replaces the automatic bar line; otherwise
  the specified symbol appears in the middle of the measure.   The
    code(\bar) command does not affect metric structure.


  
dit(code(\partial) var(duration)) some music starts with a measure that
isn't fully filled, a so-called upstep.  The code(\partial) command
allows you to make
upsteps. The argument is a duration similar to the duration of a note.
The `code(\partial)' command cannot be used to generate partial
measures in the middle of the music.  
Example:
  mudela(fragment,verbatim)(
    \time 4/4;
    \partial 4;
    [d'8 dis'] e' c''4 e'8 c''4 
  )

  dit(code(\grouping) var(durationslist)) sets the metric structure of the measure.
    Its effect can best be shown by an example:
    mudela(fragment,verbatim)(
        \time 5/16;
        \grouping 16*3 16*2;
        [c'8 c'16 c'8]
        \grouping 16*2 16*3;
        [c'8 c'16 c'8]
        \grouping 16*5 ;
        [c'8 c'16 c'8]
    )

In practice, you won't be needing this command very often: the
grouping is switched automatically when you issue a code(\time)
command.  It is set to a combination of groups
of 2 and 3 beats, with as many groups of
3 as possible (in other words: 4/4 is divided in two times two beats
(2+2), 8/8 in 3+3+2)
)

The commands that are described above aren't really music, but they
can be used in the same places as notes.  This makes the grammar of the
language simpler.  It is possible to put a command into a chord.
For example, the following two snippets of Mudela produce identical output.
verb(
  <c4 e g \time 2/4;>
  \time 2/4; <c4 e g>
)



sect(Complex music: more than one staff)
label(tutorial:more-staffs)


Now we explain how to typeset music that runs in multiple staffs.
Consider the following---somewhat unrealistic---example:

mudela(fragment)(
 \type GrandStaff <e'4 {\clef bass; g4^""} >
)

  The music consists of two notes.  Perhaps this is sheet music for a
piano player, and one note is meant to be played with the left hand,
and the other with the right hand.  That music would sound the same if
it were written as a single chord on a single staff, i.e.,
mudela(fragment)(
  <g4 e'4>
)


This is another example where we can see that there can be a difference
between a musical idea, and the way it is expressed in notation.

The Mudela construct for multiple staffs reflects the similarity
between the two examples: to get multiple staffs in Mudela you enter a
chord, with an additional instruction to tell LilyPond that the chord
does not represent notes stacked together, but staffs stacked
together.

If a piece of music is to be interpreted as a staff, then this can be
expressed with the code(\type) construct.  The following input says
``the quarter note with pitch e should be put on a staff.''

verb(
  \type Staff e'4 
)

The same can be done for the other note, i.e.,

verb(
  \type Staff g4 
)

If you want to stack these staffs, you must create a chord of both:

verb(
  < \type Staff e'4
    \type Staff g4 
  >
)

This looks reasonable, but the effect of this input is not what you
might expect (try it!).  When interpreting this chord LilyPond will
start with the first entry.  She'll look for a (nameless) staff.  Such a
staff is not found, so it is created.  On this staff the code(e) note
is put.  When the second code(\type) entry is read, LilyPond will
start looking for a nameless staff.   The  staff that contains  the
code(e) is found, and the code(g) is put there as well.

The correct solution is to label both code(\type) constructs with
different names, for example code(trebleStaff) and code(bassStaff).
This makes LilyPond distinguish between them, and create two staffs:

mudela(verbatim,fragment)(
  < \type Staff = trebleStaff e'4
    \type Staff = bassStaff  g4 
  >
)

The names that you choose do not matter just as long as they are
different.  This is almost right, except for the brace at the left and
the clef of the second staff.  The bass clef will be taken care of in
the next section. If you want a brace, then you have to tell LilyPond
that the chord you just formed is to be interpreted as a so-called
grand staff.  This is also done with the code(\type) command.
mudela(verbatim,fragment)(
  \type GrandStaff <
     \type Staff = treblestaff  e'4 
     \type Staff = bassstaff  g4 
  >
)

sect(Appending instead of stacking: sequential music)
label(tutorial:voice)

The previous section dealt with a pretty hypothetical situation: sheet
music with two staffs and each staff containing only one single note.
In real-life situations staffs contain more than one note.  They
contain music that has to be played in sequence.  A staff can contain
a em(voice).  We haven't learned  how to make a voice yet: we need a
new construct to express this notion of `voice'.

The construct is called em(sequential) music.  A list of musical
objects (e.g., notes, chords or commands) can be made into sequential
music by enclosing the list in braces; for example:

mudela(fragment,verbatim,center)(
  { c'4 c'4 }
)
mudela(fragment,verbatim,center)(
  { <c'4 e'> <e' g'> }
)


We could have called this construct more colloquially `voice', but
this would cause confusion later on, when a second kind of voice
enters the scene.  Similar confusion might arise from the word
`chord', therefore from now on, we will talk about `simultaneous
music', when we refer to items enclosed in < and >.


The notion of a em(new) construct needs some explanation: we have been
using sequential music all the time, except that it was hidden in the
red tape in bind(Section)ref(tutorial:introduction).



If we want to put whole voices onto a staff, then we have to
substitute sequential music for the single notes in the example from
the previous section.  A code(\clef) command in the second piece of
sequential
music  will also set the clef in
the bass staff.
mudela(fragment,verbatim)(
    \type GrandStaff <
     \type Staff = treblestaff  { e'4 f'}
     \type Staff = bassstaff  {\clef "bass"; g a }
  >
)

COMMENT(You can nest simultaneous music and chords in any way you want.  If
you are interested in the entire story, you should consult
bind(Chapter)ref(chap:features), which has a grammar in
bind(Section)ref(sec:grammar).)

sect(Notation context)

This section is about translation contexts, a topic of LilyPond that
is somewhat advanced.  You don't have to understand this to use
LilyPond to print simple music.  If you don't want to typeset fancy
polyphonic music or tweak the LilyPond notation engine, you can skip
the next two sections.

In bind(Section)ref(tutorial:more-staffs) it was explained, that there
are more ways to notate a simple chord: as a single voice on a single
staff or in multiple staffs (and we'll soon see, that you can typeset
it as multiple voices on a  staff).  Obviously the concept of staff is not
really something musical.  But what is it then?


The most simplistic explanation is: a staff is a peculiarity of the
notation system.  In other words, a staff is a graphic device, a
special picture of five lines on which one can print note heads.  To
avoid confusion, we will call this view on the concept of staff
`staff symbol' from now on.


There is more to it than meets the eye and mind.  A staff
contains---besides a staff symbol--- some more components:
itemize(
it()A staff can a have a key signature (printed at the left)
it()A staff has bar lines
it()A staff has a clef (printed at the left)
)
To explain what a staff really is,   we'll try to print music without
these components.  If these components aren't printed, it is still
possible to print music:
mudela()(\score{
\notes \relative c' {  \time 2/4; g'4 c,4 a'4 f4 e c d2 }
\paper { 
  linewidth = -1.;
  \translator {
    \type "Line_group_engraver_group";
    \name Staff ;
    defaultclef = violin;

    \consists "Timing_engraver";
    \consists "Separating_line_group_engraver";

    \accepts "Voice";
  }
 }
})

As you can see, one can still make out the general form of the melody
and the rhythm that is to be played, but the notation is difficult to
read and the musical information is not complete.  The stress pattern
in the notes can't be deduced from this output.  For this, we need a
time signature:

mudela()(
\score {
  \notes \relative c' {  \time 2/4; g'4 c,4 a'4 f4 e c d2 }
  \paper{
  linewidth = -1.;
    \translator {
    \type "Line_group_engraver_group";
    defaultclef = violin;\name Staff;
    \consists "Time_signature_engraver";
    \consists "Separating_line_group_engraver";
    \accepts "Voice";
  }
 }
})

Technically speaking you know where the strong and weak beats are, but
it is difficult to find them quickly.   Bar lines  help you in finding
the location within the measure of the notes:
mudela()(
\score {
  \notes \relative c' {  \time 2/4; g'4 c,4 a'4 f4 e c d2 }
  \paper{
  linewidth = -1.;
    \translator {
    \type "Line_group_engraver_group";
    defaultclef = violin;\name Staff ;
    \consists "Bar_engraver";
    \consists "Time_signature_engraver";
    \consists "Separating_line_group_engraver";
    \accepts "Voice";
  }
 }
})

We can remedy part of the difficulties with reading pitches by adding a staff
symbol:

mudela()(\score{
  \notes\relative c' { \time 2/4; g'4 c,4
a'4 f4 e c d2 } \paper {
  linewidth = -1.;
  \translator {
    \type "Line_group_engraver_group";
    \name Staff ;
    defaultclef = violin;
    \consists "Bar_engraver";
    \consists "Time_signature_engraver";
    \consists "Staff_sym_engraver";
    \consists "Separating_line_group_engraver";

    \accepts "Voice";
  }
 }
})

This makes the output decidedly easier to read, but you still don't
know what the pitches of the notes above are.  So this is still not
enough.  But suppose you see the following notation:
mudela()(\score {
  \notes \relative c' {\clef alto;  \time 2/4; g'4 c,4 a'4 f4 e c d2 }
\paper {
  linewidth = -1.;
   \translator {
    \type "Line_group_engraver_group";
    \name Staff;
     defaultclef = violin;
    \consists "Bar_engraver";
    \consists "Time_signature_engraver";
     \consists "Clef_engraver";
     \consists "Staff_sym_engraver";
     \consists "Timing_engraver";
     \consists "Separating_line_group_engraver";

    \accepts "Voice";
  }
 }
})

Now you know the pitch of the notes: you look at the start of the line
and see a clef, with this clef, you can determine the notated pitches.
You have found the em(context) in which the notation is to be
interpreted!

So the context determines the relationship between a piece of music
and its notation: you, the reader, use context to deduce music from
notation.  Because LilyPond is a notation ``writer'' instead of a
reader, context works the other way around for Lily: with context a
piece of music can be converted to notation.
The components of a staff form context, and context is needed to read
and write notation.  This motivates the following definition.

quote(
A bf(notation context) is  a conversion from music to notation.
)

The example focused mainly on on staffs, but a staff is not the only
type of notation context.  Notation contexts may be nested: you can
print polyphonic music by putting multiple `Voice' contexts in one
`Staff' context.  The arguments of the code(\type) command (Staff,
GrandStaff) were in fact all names of different contexts.
The notions of ``current clef'' and ``current position within the
measure'' are all properties of notation contexts.  Commands like
code(\clef) and code(\cadenza) change these properties.  


The following is a list of the contexts that are supported by
LilyPond:
description(

dit(Voice) The code(Voice) context is a context that corresponds to a
  voice on a staff.  This context handles the conversion of noteheads,
  dynamic signs, stems, beams, super- and subscripts, slurs, ties and rests

dit(Staff) The code(Staff) context handles clefs, bar lines, keys,
  accidentals.  A code(Staff) context can contain multiple code(Voice)
  contexts.

dit(RhythmicStaff) The code(RhythmicStaff) context is like the staff,
  but much simpler: the notes are printed on one line, and pitches are
  ignored.  code(RhythmicStaff) can contain code(Voice) contexts.

dit(GrandStaff) A code(GrandStaff) context contains code(Staff)
  contexts, and it adds a brace to the output at the
  nop(left.)footnote(This is a major deficiency in the current
  implementation.    Currently stems,
  slurs and beams cannot be printed across two staffs.
In reality, a grand staff is  a hybrid of one big staff and two stacked staffs.)
  
  A code(GrandStaff) context can contain multiple
  code(Staff)s. Typically, it will contain two code(Staff)s, one
  treble staff, and one bass staff. The bar lines of the contained
  staffs are connected vertically.

dit(StaffGroup) A code(StaffGroup) context contains code(Staff) or
  code(Lyrics) contexts, and prints a bracket at the left.  The bar
  lines in the participating staffs are connected.

dit(Lyrics) As its name suggests, The code(Lyrics) context deals with
  typesetting lyrics.  This topic will be covered in
  bind(Section)ref(tutorial:lyrics).
  
dit(Score) The code(Score) context is the toplevel context: no context can
  contain a code(Score) context.  The code(Score) context handles the
  administration of time signatures.  It also makes sure that items
  such as clefs, time signatures, and key-signatures are aligned across staffs.
  
  The code(Score) can contain code(Staff), code(StaffGroup), code(Lyrics), code(GrandStaff) and
  code(RhythmicStaff) contexts.

COMMENT(do ChoireStaff)
)


  Later on, in bind(Section)ref(tutorial:engravers) we will
explain how you can create your own contexts.

If you are familiar with structured documents (like HTML, SGML or
LaTeX()), you might see the analogy of a context with a stylesheet: a
stylesheet is neither presentation nor information, but rather a
recipe em(how) a specific piece of information should be presented.
Analogously, a notation context is neither music nor notation, but the
conversion between the two.  The big difference with text is that in
music notation the elements provided by context are essential to
understanding what is notated.



sect(Polyphonic music (or: Notation context properties))

In the last section we explained that a notation context can have
properties that influence the conversion from music to notation.  A
simple example of such a property is the clef: the type of clef partially
determines the vertical position of note heads in a staff.  Some of
these properties can be modified by commands such as code(\clef) and
code(\time).   But there is more:  notation contexts  also have
properties are settable in a generic fashion.  We will demonstrate
this feature by printing multiple voices on a staff.

In polyphonic (keyboard) music and orchestral scores often more than
one voice is printed on one staff.  We'll explain how to achieve this
effect with LilyPond.  The effect is not unlike the two stacked staffs
from bind(Section)ref(tutorial:more-staffs), except that we don't want
to stack staffs but voices.  Thus,  the general template is the following:
verb(
  \type Staff <
    \type Voice = one  ...
    \type Voice = two  ...
  >
)

On the ellipsis there should be music going from left to right, in
otherr words, there should be sequential music, notes enclosed in
braces.  Let us try the following simple melodies:

mudela(fragment,verbatim)(
\type "Staff" <
  \type "Voice" = "one" { r4 as'4 () as'4 g'4 }
  \type "Voice" = "two" { g'2 f'4 e'4 }
>)

As you can see the result is not quite perfect.  The notes on the last
two beats look like plain chords and not like separate voices.  What
really happened was that the stems of the upper and lower voices were
printed on top of each other.  If you have tried running this example, you will probably
have noticed a complaint  about ``too many
clashing notecolumns''  during the LilyPond run.
This complaint refers to the overlapping stems.

To remedy this, engravers traditionally make the stems of the upper
and lower voice point in different directions: the stems of the lower
voice point down, and the stems of the upper up, as shown in
bind(Figure)ref(tutorial:multi-voice-fig).

Surely the direction of a single stem is a property of the stem as a
graphical object.  But the fact that all of the stems in a voice point
in the same direction is not directly graphical.  Since this is a
property shared by all the stems in the voice, it is logical to
consider this property to be a property of the context code(Voice).
And this is how it's done in LilyPond: the context code(Voice) has an
attribute whose value is the direction to use
for stems.  You can change it to `up'
by issuing the following phrase:footnote(The name code(ydirection) is
no mistake.  The property also controls the up/down directions of
super-/subscripts, slurs, ties, etc.)

verb(
  \property "Voice"."ydirection" = "1"
)

This command should be read as ``change the property called
code(ydirection) within the current code(Voice) context to the value
code(-1).''  For the property code(ydirection) the value code(1) means
`up', and code(-1) means `down'.   The proper way to code the
polyphonic example is given in bind(Figure)ref(tutorial:multi-voice-fig).

latexcommand(\begin{figure}[h])
mudela(fragment,verbatim,center)(
  \type "Staff" <
    \type "Voice" =  "one"  {
      \property Voice.ydirection = "1"
      r4 as'4 () as'4 g'4 }
    \type "Voice" =  "two"  {
      \property Voice.ydirection = "-1"
      g'2 f'4 e'4 }
  >
)
    latexcommand(\caption{multiple voices})
    label(tutorial:multi-voice-fig)
latexcommand(\end{figure})

Other properties can also be set, and they can be within different
contexts.  In general, you can set a property by specifying
code(\property) var(contexttype)code(.)var(propertyname) code(=)
var(value).  Both var(ContextType), var(PropertyName) and var(Value)
should be strings.

The effect of a property is pretty much hardwired into the
implementation (and thus subject to change), so we will not deal with
all the possible properties in detail. Among other characteristics that
can be set are the layout of slurs and beams.  The initialisation file
file(property.ly) explains most properties.

We conclude this section with another example of a context property.
Polyphonic music that has three or four voices can't be printed by
simply changing the directions of the stems for each voice, obviously.
Traditionally, some chords are shifted horizontally to print if this many
voices have to be printed.
LilyPond can also do this, and the property that controls the
horizontal shifting is called code(hshift).  The notes in a
code(Voice) context that has code(hshift) set to a true value (i.e.,
non-zero or non-empty), will be shifted horizontally in the case of a
collision.  The following example demonstrates the effect.

mudela(fragment,verbatim)(
  \type "Staff" <
    \type "Voice" =  "one"  {
      \property Voice.ydirection = "1"
      r4 as'4 () as'4 g'4 }
    \type "Voice" =  "two"  {
      \property Voice.ydirection = "1"
      \property Voice.hshift = 1
      g'2 f'4 e'4 }
    \type "Voice" = "three" {
      \property Voice.ydirection = "-1"
      [d'8 dis'] [d' cis'] [c' b] c'4
    }
  >
)

sect(Lyrics)
label(tutorial:lyrics)

Now for something completely different: Lyrics.  Lyrics are also
considered to be music, although a lyric by itself does not have any
pitch.  Producing lyrics has two aspects. First, you have to enter the
text, i.e., the syllables along with their durations.  
After this, you have to specify how to convert these to graphics.

Lyrics consist of syllables, which are strings together with
durations.  Previously we only entered note names, so for entering
lyrics we have to instruct LilyPond that what we enter are not note
names but words---or rather: strings.  This instruction is the keyword
code(\lyrics).  After entering this keyword you can enter a musical
construct---sequential music, simultaneous music, code(\type)
entries, etc.--- but with syllables in stead of pitches.  For example:
verb( \lyrics { 'got8 me on my knees4, Le-8 lie! })

The effect of code(\lyrics) can be compared with the effect of the
doublequote character, code("), for it also changes the lexical
meaning of spaces and characters.  This mode is another example of a
handy input feature of the language.

Next comes the conversion to notation.  LilyPond can't (yet) figure
out that lyrics need different treatment than notes.  As a result, the
default conversion will try to put the text you entered as note heads
onto a staff, and this will fail.  This default must be overriden with
a code(\type) keyword.  Printing syllables of text in a line is done
by a context called code(Lyrics).  You can select this context with
the code(\type) keyword.  Here is a simple example:

mudela(fragment,verbatim)(
        \type Lyrics \lyrics { 'got8 me on my knees,4 Le-8 lie! })

The result is technically more or less correct, but without a melody it
just doesn't work, so let's add a blob of cream:
mudela(fragment,verbatim)(
  <
    \type Staff  { c''8. c''16 bes'8. a'16 g'4 f'8 g'4. }
    \type Lyrics \lyrics { 'got8. me16 on8. my16 knees,4 Le-8 lie!4. }
  >
)

The strings that makes up each syllable in the lyrics block are passed
along to TeX() verbatim, so if you are proficient with TeX() you can
do various nifty things.  Just keep in mind that a syllable either
starts with a letter (a character in the range `code(a)' to `code(z)'
or `code(A)' to `code(Z)'), or it is a string enclosed quotes. It ends
with either a number for the duration, or a space.  A last feature
that should be mentioned is the space-lyric: if you want to enter
a single ``syllable'' that consists of multiple words, i.e., words
separated by  spaces, you should use an
underscore instead of a space.  All these tricks are demonstrated in
the following example:

COMMENT( urg
\type Lyrics \lyrics { 'got_m\textbf{e}4 on8. m$\cal_Y$16 knees,4 Le-8 lie!4.}
\type Lyrics \lyrics { 'got_m{\bf e}4 on8. m$\cal_Y$16 knees,4 Le-8 lie!4.}
)

mudela(fragment,verbatim)(<
  \type Staff  { c''8. c''16 bes'8. a'16 g'4 f'8 g'4. }
  \type Lyrics \lyrics { 'got_me4 on8. m$\cal_Y$16 "3s,"4 Le-8 lie!4.}
>
)

The spacing in the above example is a bit skewed because Lily can't
tell that the long syllables you entered are not ordinary characters,
but expand to really small symbols.




COMMENT(Rood is de kleur van geluk.)
COMMENT(Dat geldt ook voor haar.)


sect(Toplevel Mudela)

Now the time has come to unravel the red tape that we have hidden from
you in the introduction.  Mudela has a hierarchical structure for we
have seen that sequential and simultaneous music can be nested.
Mudela also has other `blocks' that can be nested.  The general syntax
for a block is code(\keyword { ... }).

When you run LilyPond, what happens is that you define music, and
specify one (or more) conversions to apply to that music, for example
a conversion to notation.  This is done by putting the definition of
the music and the definition of the conversion together in a
code(\score) block, e.g.,
verb(
\score {
        % ... music ...
        \paper {}
})

This is almost  the context that should be around all
of the previous examples.  The precise context reads thus:
verb(
\score {
        \notes { ... }
        \paper {}
})
On the ellipsis, you entered what shown as the example input.
You can see that in the
above example, the code(\notes { ... }) forms the music, the
code(\paper {}) is a conversion to paper (notation, that is).  The
code(\paper) definition is copied from a default definition
(which is in the initialisation file file(paper16.ly)).
The paper part also contains
the definition of the contexts.

The keyword code(\notes) is analogous to the code(\lyrics) keyword.  It
will switch the tokenizer into a mode that interprets plain words as
note names.  If it can't recognize the words as a note name, it will
assume that they are strings.  That is the reason why you can write
code(\clef bass) in stead of code(\clef "bass"); most of the strings
in code(\notes) mode can be written without quotes.

The braces that you see after the code(\notes) keyword are the
braces that are around sequential music.  Because of these braces, the
sequences of notes in our simple examples were sequential (and not
simultaneous).  As a result the notes were printed from left to right,
and not stacked.

sect(Identifiers)


Now that we are comfortable with the toplevel entries in a mudela
file, we can investigate some more of the recreations on toplevel, in
particular em(identifiers).  Generally you can define an identifier by
entering code(identifierName = ... )
where there can be a variety of things on the ellipsis.

Here is a (partial) list of what you can abbreviate with identifiers
at top-level.
itemize(
it()The code(\score) block
it()The code(\paper) block
it()The code(\midi) block (to be explained in
  bind(Section)ref(tutorial:sound))
it()Music (sequential music, simultaneous music etc.)
it()Durations
it()Strings
it()Translators (to be explained in bind(Section)ref(tutorial:engravers))
it()Integers
it()Reals  
)

When you refer
to the abbreviated entity, you must precede code(identifierName)
with a backslash, i.e., code(\identifierName).  For example:
mudela(verbatim)(
  czerny = \notes { [c16 g e g] }
  \score {
    \notes \type GrandStaff <
      { c''2 g''2 }
      { \clef bass; \czerny \czerny \czerny \czerny}
    >
    \paper {
      linewidth = -1.0;
      stem_length = 6.0*\interline;
    }
  }
)



Another interesting feature of this example are the assignments within
the paper block.  Some blocks, such as code(\paper), have a scope of
their own.  In the case of the code(\paper) block, these variables
influence the characteristics of the output.  As is shown, you can
tune quantities like the stemlength, and enter simple expressions.
The purpose of the negative linewidth is to prevent the music from
being justified.  The identifiers that are meaningful are for the
paper block is strongly implementation dependent, so they will not be
listed here.  Moreover, since most of the values are predefined to
sensible defaults, there usually is no need to tune these values.

Recall the properties of a context, that could be set with
code(\property).  It is a very general mechanism to tune the output of
the music, that is neatly separated from the real music.
Unfortunately, it is not convenient to type or read, and the precise
effect of a setting property isn't always apparent from its
definition.  To remedy this, we can use an identifier to capture the
meaning of a code(\property).

mudela(verbatim)(
stemup = \property Voice.ydirection = "1"
stemdown = \property Voice.ydirection = "-1"
shift = \property Voice.hshift = "1"
\score {
  \type "Staff" \notes <
    \type "Voice" =  "one"  {
      \stemup
      r4 as'4 () as'4 g'4 }
    \type "Voice" =  "two"  {
      \stemup
      \shift
      g'2 f'4 e'4 }
    \type "Voice" = "three" {
      \stemdown
      [d'8 dis'] [d' cis'] [c' b] c'4
    }
  >
  \paper{  linewidth = -1.0\pt; }
}
)

Several abbreviations like code(\stemup) are defined in the
standard initialisation file file(property.ly).  Setting or changing
context properties can have a similar effect as the commands that were
discussed in bind(Section)ref(sec:commands).  Don't be fooled by the
similarity in appearance between a declared property-setting entry
and a real command.  Real commands are hardcoded into the language
and they have to be terminated by semicolons.

You can also use identifiers to break up the heavy nesting that can occur
in the code(\score) block.  Another useful application is
parametrisation of the music: if you use identifiers in the
code(\score) block, you can make variations of the music by simply
redefining those identifiers.  One particular application of this is
part extraction: by using identifiers and redefining them, one can
print extracted parts and a full orchestral score from the same
music definition.



sect(Sound output)
label(tutorial:sound)

You get output by combining music with definition a conversion to
output.  Up till now we have only focused on the graphic output of
traditional engraving.  But there is no reason why that should be the
only form of output for music.  LilyPond currently supports one other
conversion: the conversion from abstract music to sound. You can have
LilyPond play the music that you entered.  The format that is used
for this output is MIDI.  

The only information that you need to enter is the
 nop(tempo)footnote(Unfortunately,
this the only thing that can be tuned at this
time.  This is a limitation: the tempo of music can vary throughout
the music.) for the performance.  The syntax for the tempo is
code(\tempo )var(duration) = var(beatsperminute);), for example:
verb(
\score {
   ...music...
   \midi { \tempo 4 = 76; }
}
)

The most useful purpose of this sound output is to prooflisten your
files: typing errors (especially if they involve accidentals)  stand
out when you listen.
The output was implemented in a very rudimentary manner, so it is
probably not worth listening to for any other reason.


sect(Contexts revisited: engravers)
label(tutorial:engravers)

As was promised, we will now take a dive into the more wizardrous parts
of LilyPond: redefining (notation) contexts.  We previously explained
that a context 
itemize(
it()is a conversion from music to notation,
it()can contain other contexts
it()handles specific notation constructs
)

This characterization almost automatically explains what the definition of a
context should look like:
itemize(
it()It should be part of the ``notation output definition,'' i.e., the
  code(\paper) block
it()
  It should contain a specification of what other contexts may be contained
  in the context we're defining.
it()
  It should contain a list of the notation constructs  to be
  handled.
)

In practice, the context definition
looks like this:
verb(
\translator
{
        \type "Engraver_group_engraver";

        \name "ContextName";

        \accepts "...";
        \accepts "...";
        \accepts "...";



        \consists " ... ";
        \consists " ... ";
        \consists " ... ";

        propertyname = "value";
        propertyname = "value";

} )

  This is encoded by the 

The code(\translator) keyword opens the block for translation (or
context) definition.  The code(\type) keyword explains to Lily that
the context should be formed by taking an (empty) instance of
code(Engraver_group_engraver).  The code(Engraver_group_engraver) is a
C++ class from the source code to Lily.  The code(\accepts) entries
explain what kind of contexts this context could contain.  If we were
to define a context for a staff, the definition would typically
contain code(\accepts "Voice";).

The code(\consists) entries specify which notation constructs should
be handled. This needs a little explanation: LilyPond contains the
code for quite a large number of basic building blocks for notation
generation, and each building block handles only one notation
construct.  The name of such a building block is `engraver'.  You can
specify which notation construct a context should handle by specifying
which engravers should be part of the context.  The code(\consists
"Foobar") entry really means ``add an instance of code(Foobar) to the
translation group.''


For example if this context should print time signatures, the definition
should include `code(\consists "Time_signature_engraver";)'.  Again
code(Time_signature_engraver) is a class from the source code of LilyPond.



Finally, one can pre-set some properties in a context definition.

As a practical example, we will show you how to typeset polymetric
music, i.e., music where the meter can differ for each staff.  The
solution is not very complicated: normally all timing information
(time signature, rhythmic grouping) is synchronised across each staff.  In
LilyPond this is expressed by having only one registration for timing
information for all staffs.  To be precise, there is only one
code(Timing_engraver), and it is located in the top level context, the
code(Score) context.

All staffs use the information in the global code(Timing_engraver)
for generating bar lines and time signatures.  In polymetric music, this timing
information can be different for every staff, so we should redefine
the code(Staff) context to include and the code(Score) context to exclude the
code(Timing_engraver).  

mudela(verbatim)(
polymetricpaper = \paper {
  \translator {
    \ScoreContext
    \remove "Timing_engraver";
  }

  \translator {
    \StaffContext
    \consists "Timing_engraver";
  }
}
\score {
  \notes <
    \type Staff = one { \time 2/4; c'4 c'4 c'4 c'4 c'4 c'4 }
    \type Staff = two { \time 3/4; c'4 c'4 c'4 c'4 c'4 c'4 }
  >
  \paper { \polymetricpaper
    linewidth = -1.;
  }
}
)

As you can see, we used the identifier code(polymetricpaper) to break
up the large score block.  More of these context definitions appear in
the standard initialisation file file(engraver.ly).

sect(Urtexts and context selection)
label(tutorial:urtext)

In bind(Section)ref(tutorial:more-staffs), we have shown you how to make
multiple staffs, and explained that you have to label every staff (or
more precisely: different contexts), to make sure that new ones are
created when you need them.  In this section, the real power of this
mechanism will unveiled.

By naming other contexts that you create, you can reference other contexts
than the current context from within the music.  For example, from within the music that you
enter for staff code(One), one could enter a small piece of music,
and send it to staff code(Two), e.g.,
mudela(fragment,verbatim)(
  <
    \type Staff = one { c''4 \type Staff = two { c4 c4 } c''4 }
    \type Staff = two { \clef bass; g,4 g,4 g,4 g,4  }    
  >
)


Another useful application of this feature is making Urtexts.
em(Urtext) is the German word for `original text'.  The Urtext
edition of a piece of music, is an edition that reflects the original
writing of the composer.  Such editions are useful for musicologists,
and performers that want  to perform authentic interpretations.  However,
for mere mortals, the Urtext can be quite hard to read.  It might not
contain fingering and beaming, and typically it is full of footnotes.
Moreover, common interpretations may have emerged---after the composer
died.  For this reason, the music that can be had as Urtext usually is also
available in enhanced and edited editions.

The mechanism of context selection can be used to fabricate an Urtext
and an edited edition from em(one source).  We will use the first few
bars of bind(J.)bind(S.)Bach's lovely Cello suite bind(no.)I to
demonstrate this.  The example makes heavy use of space rests: a space
rest takes up time, like a rest does, but it doesn't print anything.
It can be used as a placeholder, to attach articulation marks to.  It
is entered as a note with the name code(s).

mudela(verbatim)(
  bach =  \notes { [c16 g e' d'] [e' g e' g] }
  
  staffStuff = \notes { \clef bass; \time 4/4; s1 \bar "|."; }
  
  slursOne = \notes { s16( s s s s16 s s )s }
  slursTwo = \notes { s16-. s s() s s16() s  s ()s }

  \score{
    { < \type Voice = celloVoice { \bach \bach }
        \type Voice = celloVoice { \slursOne \slursOne }
        \staffStuff
      >
      <
        \type Voice = celloVoice { \bach \bach }
        \type Voice = celloVoice { \slursTwo \slursTwo }
        \staffStuff
      >
    }
    \paper {}
  }
)

 The slurs that you define should be put on the music that is defined
by the code(\bach) identifier.  By labeling a code(Voice) context, and
directing both the articulation and the notes to that same code(Voice)
context, the articulation is put over the right notes.


sect(Transposing)
label(tutorial:more-grammar)

COMMENT(In this section, we will complete the grammar for Music that was
sketched earlier. )
One of the things that you can do with music is
em(transposing) it.  If you want to transpose a piece of music, then
you should prefix the keyword code(\transpose) along with the pitch
(relative to the central C) for the transposition.footnote(the
code(\type Staff) is to make sure that no separate staffs are created
for the code(\scale) and code(\transpose cis' \scale) part.)


mudela(verbatim)(
scale = \notes \relative c' { [c8 d e f] }
\score {
  \notes {
    \type Staff { \scale \transpose cis'  \scale }
    }
  \paper { linewidth = -1.0; }
})


sect(Staff switching)

We have seen that contexts can be nested.  This means that they form a
tree.  It is possible to edit this tree: for example, a code(Voice)
context can be taken out of a code(Staff) context, and put into
another.  This has the effect of the voice switching staffs (something
that often happens in keyboard music).  The syntax for this operation
with these particular contexts is code(\translator Staff = newStaffName).

The effect is analogous to the first example in section
ref(tutorial:urtext), but with the code(\translator) construction it
is possible to split the real music and the commands that determine in
which staff the music is printed.  For example:

mudela(verbatim)(

% real music
aVoice = \type Voice = voiceA \notes { c''4 c4 c4 c''4 }
bVoice = \type Voice = voiceB \notes { g,4 g,4 g,4 g,4  }    

% staff switching stuff
switch = \type Voice = voiceA \notes { s4 \translator Staff = staffB s4
                   s4 \translator Staff = staffA s4 }

\score {
  <
    \type Staff = staffA < \aVoice \switch >
    \type Staff = staffB < \bVoice \clef bass; >
  >
  \paper { linewidth = -1.; }
}
)

Don't try to switch staffs when you are in the middle of a slur or
beam, though.  It doesn't work yet.

sect(Hairy durations: triplets)

In the previous section we explained an operation that changes the
pitches of music, transposition.  In this section we will explain an
operation that modifies the duration of the notes that you enter.
When notes are part of a triplet, then the real of duration of the
notes are 2/3 part of what their shape indicates:
mudela(fragment)(
\[/3  c'4 c'4 c'4 \]/1
)

To support this notion, Mudela allows you to modify the duration of a
note by multiplication or division.  A code(c'4) note that would be in  a
triplet is written as code(c'4*2/3).  If you sequence a few of these
notes, you get a triplet.footnote(We added a normal staff in the example to
show the difference.)
mudela(fragment,verbatim)(
<  \type Staff = staffA { c'8*2/3 c'8*2/3 c'8*2/3 c'4}
   \type Staff = staffB { c''8 c''8 c''4 } >)

LilyPond knows that these notes are no normal eighth notes, but the
reader doesn't yet.  To help the reader a beam or a bracket with a `3'
should be printed.  The special beam command `code([2/3)' and the
matching close beam `code(]1/1)' will take care of that, and
they also abbreviate the code(*2/3) part.  If you want brackets in
stead of beams, you can use `code(\[2/3])' and `code(\]1/1)'.
mudela(fragment,verbatim)(
< \type Staff = staffA {
    [2/3 c'8 c'8 c'8 ]1/1
    \[2/3 c'8 c'8 c'8 \]1/1
  }
  \type Staff = staffB { [c''8 c''8 c''8 c''8] }
>)

Other tuplets  can be entered in the same way.
mudela(fragment,verbatim)(
< \type Staff = staffA {
    \time 7/8;
    [7/6 c'8 c'8 c'8 c'8 c'8 c'8 ]1/1
  }
  \type Staff = staffB {
    \time 7/8;
    [c''8 c''8 c''8 c''8 c''8 c''8 c''8] } >
)

For your convenience, code([2/3) can be further abbreviated to code([/3), and
you can abbreviate code(]1/1) on the closing beam marker to code(]/1).

mudela(fragment,verbatim)(
< \type Staff = staffA {
    [/3 c'8 c'8 c'8 ]/1 c'4
  }
  \type Staff = staffB { [c''8 c''8] c''4 } >
)


bf(Important) the construct with code([/3) and
code([/1) is a hack that sets a mode in the parser.  This means that
verb(id = \notes { c8 c8 c8 }
notATriplet =\notes { [2/3 \id ]1/1 })
does not produce a triplet.  It will hopefully
soon be replaced by a construction that mixes more elegantly with the
grammar for Music.


sect(Shortcuts for octaves)
label(sec:relativeoctaves)

Plain Mudela contains a lot of quotes to get the octaves right.  This
need for quotes can be reduced: most of the pitch intervals in
conventional music are small.  Therefore, it makes sense to leave out
the quotes when the interval is small.  We have built a mode that does
exactly this.  It is called the relative mode for octaves.  You can
switch it on by entering code(\relative).  Then LilyPond will
interpret every note as if they mean the note with the same name
closest to the previous.  You have to specify the first pitch because
the first note of a list obviously has no predecessor.  So, you can
enter a scale without using octavation quotes, e.g.,

mudela(fragment,verbatim)(
    \relative c' { c d e f g a b c }
)

For chords, the relative mode works slightly differently.  In a
sequence of chords, the first note of a chord gives the starting point
for the next chord.  We can demonstrate this with our twinkle twinkle example
verb(
  \relative c' {
  c4       c            <c g'>    <c e g>
  <c e a>  <b d a'>     <b2 d g>
  <a4 d f> <bes d f>    <bes c e> <g c e>
  <e a d>  <a, g' cis'> <d2 f d'>
  }
)

LilyPond converts any music with code(\relative) prepended to absolute
music immediately when it is read. Internally it is stored it in
absolute pitches.  Since the tutorial mainly deals with how to specify
musical information, and not how to enter it conveniently, the
tutorial doesn't use it.


sect(Large pieces)
label(tutorial:large-pieces)

In our quest for a clean and powerfull music language, we took the effort
of entering some larger pieces of music as well.  From this we learned
certain things that lead to direct improvements of Mudela, such as the 
relative mode.  We also gained some practial experience, that resulted in a 
compilation of tips that may be of use to you.

Entering a large piece of music will often imply the need to produce a
conductor's score, as well as individual parts for all instruments.  This
can most easily be achieved making use of identifiers and including mudela
files.

subsect(Identifiers)

Briefly introduced before, identifiers are your biggest help in structurising
a large piece of music.  As an example, we'll consider a string quartet.  
In short, it will look like this: verb(
    global = \notes{ }
    violinoOne = \notes \relative c { .. }
    violinoTwo = \notes \relative c { .. }
    viola = \notes \relative c { .. }
    violoncello = \notes \relative c { .. }
)

The code(\global) part contains everything that is global, i.e., the
same, for each instrument.  This may include time signature, key, repeat
signs, different bar types, time signature- and key changes, rehearsal
marks, etc.

For each instrument, you'll have something vaguely resembling verb(
    violinoOneStaff = \type Staff = violinoOne <
        \property Staff.midi_instrument = "violin"
        \property Staff.instrument = "Violino I"
        \property Staff.instr = "Vl. I"
        \global
        \violinoOne
    >
)


[Versions, relative mode,
 barchecks, splitting of files]

subsect(Including Mudela files)
ref(subsect:include)

You can include other Mudela files  with the command code(\include):
verb(
\include "paper13.ly"
\score {
       ...
       \paper { \paper_thirteen }
})

The file is looked for in the  standard search path.


subsect(Grouping of staffs)

subsect(Versioning)

sect(Titling)
label(tutorial:titling)

A piece of sheet music isn't complete without proper opening and
closing titles.  LilyPond does not have any real support for setting
text: that is a job best left to TeX().  But you can pass messages to
TeX() from the input file.   You can  write TeX() macros to handle
these messages.
To do this, you add a code(\header) block
to your input file.  The format is quite simple,

verb(
\header{
    "key" =  "value";
    "key" =  "value";
    "key" =  "value";
    % etc.
})

When  the results of the music typesetting are output, the contents of
code(\header) are also up into the TeX() file.  Tools like
code(ly2dvi) can use this information to generate pretty titling for
your input file. Consult the manual page of code(ly2dvi) for more
details.


The code(\header) block should be at toplevel in mudela, and
preferably at the top of the file.  If you have an input file  with
multiple code(\score) blocks, you should add a header to every score,
describing the different sub parts of the music piece, eg.


verb(\header {
        "composer" = "Ludwig Van Bavaria";
        "title" = "Symphonie Megalomane";
    }
    \score{
       ... % some music
       \header { movement = "Mit roher Kraft wild herausfahrend!"; }
      \paper { }
    }
    \score{
       ... % some more music
       \header { movement = "Saut\'e comme un oeuf."; }
      \paper { }
    }
)

If you want you can also put the code(\header) block at the top of the
input file; it will then be put into every output file automatically.
This will make it clear what the file contains as soon as you open it.