Writing music and code at the same time : Lilypond ♬♭♬

LilyPond, writing music with code

I actually learned how to read sheet music by writing code. When music scores looked like Chinese to me, writing something like c c g g a a felt very familiar, because I had learned guitar with tablatures found online. c c g g a a simply means "do do sol sol la la", and LilyPond generates a beautiful score from this simple code. Hurray!

Let's see how it works.

What is LilyPond?

LilyPond is a music engraving program, part of the GNU Project, released under the GNU General Public License. It was started in 1996 by Han-Wen Nienhuys and Jan Nieuwenhuizen, and it is still actively developed by a community of volunteers.

Its philosophy: instead of placing notes with the mouse like in a word processor, you describe the music in a text file and LilyPond computes the best possible layout, following the rules of traditional hand engraving. The result is often more elegant than commercial software, and it is used by publishers, composers, choirs and the Mutopia Project, a library of thousands of free public domain scores.

LilyPond is cross-platform and runs on Linux, macOS and Windows.

Your first score

Install LilyPond from the download page, then create a file called twinkle.ly:

\version "2.24.0"

\header {
  title = "Twinkle Twinkle Little Star"
}

\relative c' {
  \time 4/4
  c4 c g' g | a a g2 |
  f4 f e e | d d c2 \bar "|."
}

Compile it:

lilypond twinkle.ly

You get twinkle.pdf, a perfectly engraved score. Add a \midi { } block to also get a MIDI file you can listen to.

Understanding the syntax

Notes are letters: c d e f g a b. Sharps and flats use suffixes: cis is C sharp, bes is B flat (Dutch names by default, other languages are available).
Durations are numbers: 1 whole note, 2 half, 4 quarter, 8 eighth. A duration applies to the following notes until you change it.
Octaves use ' (up) and , (down). In \relative mode, LilyPond picks the closest octave automatically, which saves a lot of typing.
Bars are checked with |: if a bar is incomplete, LilyPond warns you, just like a compiler.
Chords, lyrics, dynamics, guitar tablatures, drums and full orchestral scores are all supported.

Why writing music as code is brilliant

As a developer, I find all the advantages of code applied to music:

Version control. Store your scores in Git, see what changed between two versions, collaborate with pull requests.
Variables and reuse. Define a melody once (melody = { ... }) and reuse it in the score, the MIDI and the parts for each instrument.
Separation of content and presentation. You write the music; LilyPond handles the layout, like HTML and CSS.
Automation. Generate dozens of transposed parts or exercises with a script.
Longevity. A plain text file will still be readable in fifty years, unlike proprietary formats.

Tools that make it easier

Frescobaldi: a free editor dedicated to LilyPond, with live preview and point-and-click between code and score.
VS Code / VSCodium extensions: syntax highlighting and preview inside your usual editor.
Hacklily and other online editors to try LilyPond without installing anything.
MuseScore can export to MusicXML, which LilyPond can import with musicxml2ly.

Who is it for?

Developers who play music, like me: it feels natural from day one.
Teachers who create exercises and need consistent, beautiful handouts.
Composers and arrangers who care about engraving quality.
Beginners in music theory: writing notes as text forces you to understand rhythm and intervals.

Resources

LilyPond sheet music example

Like creative coding? Discover how to draw with code using p5.js.