[lilypond.git] / Documentation / mudela-man.doc

% -*-latex-*-

% this document should be run through the mudela-book script after lilypond
% has been installed. 

\documentclass{article}
\usepackage{a4wide}
\title{GNU LilyPond input format 0.1}
\author{Han-Wen Nienhuys}

\begin{document}
\maketitle
\def\interexample{\par Produces the following:\par}
\def\preexample{\par\medskip}
\def\postexample{\par\medskip}
\def\file#1{{\texttt{#1}}}

\section{Introduction}

This document describes the the GNU LilyPond input format, which is an
effective language for defining music.  We call this language (rather
arrogantly) The Musical Definition Language or Mudela, for
short.\footnote{If anybody comes up with a better name, we'd gladly
  take this. Gourlay already uses Musical Description Language,
  G-Sharp Score Definition Language. We're not being original here}

The first aim of Mudela is to define a piece of music, 
being complete from both from a musical typesetting, 
as from a musical performing point of view.

The Musical Definition Language (Mudela), has a logical structure,
making use of identifiers, that allows for flexible input, and
definition reuse. See MANIFESTO for reasons and design considerations.

The below included for explanatory purposes only (i.e., for a complete
and up-to-date definition, see \file{lily/parser.y} and
\file{lily/lexer.l}):

As a related note, you should take a look at the examples and the init
files, as this document does not cover every aspect of mudela yet, and
may be out of date.


\section{Basic elements}

\subsection{Files}

The de-facto extension of Mudela is \file{.ly}. Files may be included by
entering \verb+include+ at the start of a line:

\begin{verbatim}
\include "a_file.ly"
\end{verbatim}


\subsection{Comments}

Line comments are introduced by a
\verb+%+. 
Block comments are delimited
by 
\verb+%{+ 
and
\verb+%}+. 
They do not nest.

\subsection{Versions}

Occasionally, small changes in syntax across different versions of
Mudela might give syntax errors. To warn you about possible
incompatibilities, you can specify the Mudela version for which the
inputfile was written,
\begin{verbatim}
\version "0.0.50";
\end{verbatim}

A perl-script which tries to convert to newer versions
(\file{convert-mudela}) is included in the LilyPond distribution.

\subsection{Words}

Keywords are preceded by a backslash: \verb+\+. They contain
alphabetic characters only.

Identifiers in their normal form consist start with a backslash, a
alpha character, followed by alpha-numerics. Identifiers can contain
any characters (except whitespace, 
\verb+$+ and \verb+%+), if you use this
construct:

\begin{verbatim}
\$i'm_a_weird!!!identifier
\end{verbatim}

(which is the identifier with the name
\verb+i'm_a_weird!!!identifier+).  \verb+$+ Takes any sequence of
characters which are not whitespace, \verb+$+ and \verb+%+.
\verb+$i'm_a_weird!!!string+

\subsection{Nesting characters}

Mudela uses the brace (\verb+{+ and \verb+}+) for most hierarchical
structures.  For chords the \verb+<+ and the \verb+>+ are used as
nesting braces.

\subsection{Constants}

Please note that -.5 is not a Real.

\begin{verbatim}
"I am a string"
-1.2e3          % a real
12              % an int
\end{verbatim}

        
\subsection{Identifiers}

When assigning identifiers you use

\begin{verbatim}
string = ...
\oldidentifier = ..
\end{verbatim}

When using identifiers they have to be escaped:

\begin{verbatim}
oboe = \melodic { ... }
\score{ \melodic { \oboe }}
\end{verbatim}
\subsection{Hierarchical structures}

The general structure consists of declarations:
\begin{verbatim}
IDENTIFIER = \TYPE{
        <type specific data>
}
\end{verbatim}
and instantiations:

\begin{verbatim}
\TYPE{ <type specific data> }
\end{verbatim}

(Currently, \verb+\score+ is the only type that can be instantiated
at top level. Currently declarations can only be done at top level)

Most instantiations that use an IDENTIFIER are specified as follows:

\begin{verbatim}
\TYPE{ IDENTIFIER [...] }
\end{verbatim}

Some exceptions on this rule have been made to prevent inputting
Mudela becoming tedious


\subsection{Modes:}

To simplify different aspects of music definition (entering the notes
and manipulating them) Mudela has a number of different input "modes":

\begin{description}


\item[Normal mode]

At the start of parsing, Mudela assumes normal mode.
In Normal mode, a word is looked up in the following order:
\begin{verbatim}
word    string
\word   keyword, identifier
\end{verbatim}
In normalmode, a word is assumed to start with an alphabetic
character, followed by alpha-numeric characters.

\item[Note mode] 
  Note mode (and thus Simple mudela) is introduced by
  the keyword \verb+\melodic+.  In Note mode, a word is looked up in
  the following order:

\begin{verbatim}
word    notename, string
\word   keyword, identifier
\end{verbatim}
In Note mode a word is considered to have alphabetic characters only.

\item[Lyric mode]
Lyrics mode (and thus Simple mudela)  is introduced by the keyword \verb+\lyrics+.

In Lyrics mode, a word is looked up in the following order:

\begin{verbatim}
word    string
\word   keyword, identifier
\end{verbatim}

In Lyric mode every sequence of non-digit and non-white characters
starting with an alphabetic character or the \_ is considered a word.

\begin{verbatim}
a&@&@&TSI|{[    % a word
1THtrhortho     % not a "word"
Leise Fl\"u\ss{}teren meine Sapfe       % 4 words
_ _ _ _         % 4 words: 4 spaces
\end{verbatim}
\end{description}

These modes are of a lexical nature. Normal and Note mode largely
resemble each other, save the possibility of entering Reals, 
meaning of \verb+_+ and the resolution of words

\subsection{Notes}

You enter a note by giving the name and the reciprocal of the duration:

\begin[fragment,verbatim]{mudela}
a'4     % dutch names
\end{mudela}

is a A-1 pitched quaver. The ' signifies an octave change.  A-1 is 440
Hz concert-pitch. \verb+c'+ is also known as the central c. More examples:

\begin[fragment,verbatim]{mudela}
'a      % 110
        a       % 220
        A       % 110, uppercase octavates down
        a'      % 440
a''     % 880
'as4.*2/3
\end{mudela}

The last one  is an A flat, (just below 110 Hz concert-pitch). The \verb+*2/3+
signifies that this note is part of a triplet (3 in stead of 2). The
duration is one and a half quaver (\verb+4.+) times 2/3.

Notenames are just a special kind of identifiers, and can be declared
for any language appropriate (see \file{init/dutch.ly}).  The default language
for notenames is defined to be dutch. In dutch, the notenames are
a,b,c,d,e,f and g. Sharps are formed by adding the extension "is",
flats by adding ``es''

\begin{verbatim}
% double sharp
cisis disis eisis fisis gisis aisis bisis
% sharps
cis dis eis fis gis ais bis
% naturals
c d e f g a b 
% flats
ces des es fes ges as bes
% double flats
ceses deses eses feses geses ases beses
\end{verbatim}

Rests are named r or s
\begin{verbatim}
r       % print a rest
s       % a "space" rest, nothing is printed.
\end{verbatim}

These notenames along with duration are enough material to construct
simple melodies:

\begin[verbatim,fragment]{mudela}
\octave c';
c4 c4 g4 g4 a4 a4 g2
f4 f4 e4 e4 d4 d4 c2
\end{mudela}

Music is able to express more. generally speaking, the other
'features' are either connected between notes (slurs, beams: spanning
requests) or attached to notes (eg. accents). The former are
implemented as START and STOP stop features and then attached to the note.

\begin{verbatim}
[]      START/STOP a beam
()      START/STOP a slur
\end{verbatim}

example: 
\begin[verbatim,fragment]{mudela}
  \octave c';
  [c8 () d8 () e8  
  e8(] [)g8 <c'8] e'8>              % NO nesting!
  [2/3 c8 c8 c8]1/1       % a triplet
\end{mudela}

Please note that these two characters do \emph{not} necessarrily nest,
they should attached to the note \verb+[ <c4 c4>]+ will generate a parse
error for this reason. 
  
\subsection{Slurs and Ties}

Ties connect the noteheads of adjacent notes. They are entered as follows:

\begin[verbatim,fragment]{mudela}
a'4 ~ a''4
\end{mudela}

Slurs connect whole chords, and try to avoid crossing stems. They are
entered as follows:

\begin[verbatim,fragment]{mudela}
a'4(  )a''4
\end{mudela}

\subsection{Scripts}

Symbols which can be put at either side (above or below) of a staff
are entered as follows:
\begin[verbatim,fragment]{mudela}
a-^     % marcato, direction: default
        a^-     % portato, direction: above note
        a_.     % staccato, direction: below note
        a^\fermata      % predefined identifier
        c_"marcato"     % add a text
        c^"marcato"
c-"marcato"
\end{mudela}

If you want to define your own scripts refer to \file{init/script.ly} for
details.


Dynamics can be put after the notename:
\begin{verbatim}
a4 \dynamic { 0 } % 0 = fff, 7 = ppp
\end{verbatim}

Mudela defines the following dynamic identifiers:

\begin{verbatim}
ppp pp p mp mf df ff fff        % df iso f, f is a notename.
\end{verbatim}
and the following abbreviations:
\begin{verbatim}
\<      %start crescendo
\>      % start decrescendo
\!      % end crescendo/decrescendo
\end{verbatim}

\subsection{Defaults}

If omit the duration of a note, a default value is substituted. For
this default value mudela uses the last duration explicitly entered.

Thus the following inputs are  equivalent
\begin{verbatim}
c4 c4 c16 c16 c16 s16 c4 c16
c4 c c16 c c c c4 c16
\end{verbatim}

If you are typing music which does not lie in the "small" and "large"
octave, you can prevent having to type \verb+'+ all the time by using the
\verb+\octave+ command: These two lines have the same pitch.
\begin{verbatim}
c'' d'' e'' c d e c d e
\octave c''; c d e ''c ''d ''e \octave c; c d e
\end{verbatim}

By default the setting of \verb+\octave+ is 0.

\subsection{Lyrics}

Lyrics in Mudela resemble Simple mudela a lot, with notes substituted
by text. 

All syllables are entered separately, separated by whitespace 
\begin{verbatim}
Twin-4 kle4 twin-4 kle4 ... 
\end{verbatim}

Two syllables or words that compose a single
duration entry are bound together using an underscore 
\begin{verbatim}
He_could4 not4
\end{verbatim}

\section{Composition: forming bigger structures}

The previous examples tacitly assumed that a sequence of notes is
printed in a left to right manner. This is not entirely correct, you
will get the bigger picture in this section. 

In mathematics you can form expressions by combining expressions,
which are ultimately some kind of atom or terminal symbol.  The same
goes for mudela: there are some basic building blocks, and by
combining those you create complex music.

You can combine music in three ways:
\begin{itemize}
\item If you enclose a sequence of music-elements in braces ( \verb+{+
    and \verb+}+ ), then you form another kind of music called (Voice) with those pieces.
  The duration of the Voice is the sum of the durations of its elements
\begin{verbatim}
{ c c g g a a g2 }      % twinkle twinkle
{ { c c g g} { a a g2 } }
\end{verbatim}
\item You can stack music by enclosing a sequence of music elements
  with \verb+<+ and \verb+>+. This is called a Chord.  The duration of a Chord is
  the union of the durations of its elements Example:
\begin{verbatim}
<a4 {cis8 cis8} e'4>      % a-major chord
\end{verbatim}
\item 
  You can form music by transposing music:
\begin{verbatim}
\transpose  
                d       % from c to the d that's one octave down
                { e4 f4 }       % the horizontal music
\end{verbatim}
\end{itemize}

Of course you can also combine these three mechanisms.
\begin{verbatim}
{ c <c e> <c e g> <c e g \transpose d' dis > }  % 4 increasing chords
\end{verbatim}

The basic building block in Mudela is called Request. Examples of
Requests are: Timing (such as Meter), Rhythmic, Melodic, Note (which is a combination of
Rhythmic and Melodic), Musicscript (put an accent over a note or
rest), etc.  For the actual up to date listing, you should consult the
LilyPond source code: the Request types form a big class hierarchy.

Normally you don't enter Requests directly, since that would be
tedious.  Mudela has standard abbreviations for the most common
combination of Requests. If you enter \verb+c4+, this is an
abbreviation for:
\begin{verbatim}
Request_chord{
  Note_req{
    notename: 0 acc: 0 oct: -1
    duration { 4}
  }
  Stem_req{
    duration { 4}
  }  
}
\end{verbatim}

The \verb+Request_chord+ is a special kind of chord which only allows
Requests as its elements.  The examples of the previous section were
processed with \verb+{+ and \verb+}+ enclosing the input.


\subsection{Voicegroups}

If more than one "voice" is in a staff, then you have the option of
putting the different voices into so called voicegroups: members of
the same voicegroup share certain characteristics, among others:

        - dynamics
        - text
        - beams and stems
        - scripts

For the actual list, see the init file \file{init/register.ly}

Putting different musical lines in to the same voicegroup effectively
makes LilyPond try to form chords of all those lines. Putting
different musical lines in to different voicegroups effectively makes
LilyPond try to set those lines as independently as possible. 

[adsolete. Has to be fixed in lily]

You can set the voicegroup of a voice with the command \verb+\group+, e.g.,
\begin{verbatim}        
        oboeI = \melodic { 
                \group "oboes"; 
                [e8 f8
                \group "+solo";
                [g16 a16 g16 fis16]
                \group "-";
                g8 f8
        }
        oboeII = \melodic { \group "oboes";
                c8 d8]
                e4
                e8 d8
        }
        ///     ...

        \staff { 
                melodicregs \melodic{ oboeI }
                \melodic { oboeII}
}
\end{verbatim}

In this example, the two oboe voices share one staff and are initially
in the voicegroup called "oboes". They will share beams, dynamics etc.
After two quavers, oboeI "pushes" its group: a new voicegroup is
created, called "oboes+solo". The \verb+\group "-"+ command makes the
voice enter "oboes" again.

Please do note that [] are voicegroup wide; the previous input is
valid: the beam, started in oboeI, voicegroup "oboes" is also ended in
voicegroup "oboes", albeit not in oboeI but oboeII

This concept may seem contorted, but it allows you to set the separate
oboe parts without changing the \verb+oboeI+ and \verb+oboeII+ (assuming that
you edit the [] in the example.)

The construct
\begin{verbatim}
< { .... } {......} >
\end{verbatim}
makes a chord (all horizontal parts are in the same voicegroup). The construct
\begin{verbatim}
< \multi 2; { ....} { .... } >
\end{verbatim}
creates horizontal parts which behave independently. You will have to
set voicegroup features by hand (\verb+\stem+ and \verb+\hshift+. See examples)

The construct
\begin{verbatim}
< \multi 3; { ....} { .... } >
\end{verbatim}
creates  a chord with each part in a different staff


\subsection{Durations}

A duration always starts with the duration type (1,2,4 etc), and then
any optional multipliers/dots

\subsection{Meters/groupings}

A meter has this form:
\begin{verbatim}
\meter 3/4 ;
\end{verbatim}

Rhythmic grouping is  a concept closely associated with this. For
example, in a 5/8 meter, the counts are grouped 2+3. In mudela this is
entered as
\begin{verbatim}
\grouping  8*2 8*3 ;
\end{verbatim}
You can start the piece with a partial measure, the command takes the
same syntax as grouping: 
\begin{verbatim}
\partial 16*3 4;
\end{verbatim}

Make the piece start with a partial measure [english translation?]
lasting 1 3/4 quaver.

These commands are also "voice elements", and constitute simple mudela
(consisting of stuff with duration 0).

\subsection{Examples}

Examples are included with the GNU LilyPond distribution. For the sake of
maintenance no long examples are included in this document.


\section{History}

This language has a number of roots. First and foremost, GNU LilyPond's
predecessor mpp was the inspiration of simple Mudela.  Secondly, the
hierarchical structure looks a lot like Rayce's (Rayce is a raytracer
that I've written as a hobby project. ), which in turn owes a lot to
POVRay.

Now, we know, musictypesetting and raytracing do not necessarily
require the same input format, and we know that a lot more ways exist
to convert music to ASCII, but we did give this language some
thoughts. As always suggestions are appreciated.

\end{document}