strudel-of-lilypond

A Rust tool that converts LilyPond music notation to Strudel live coding patterns. LilyPond is a music engraving program that uses text-based notation; Strudel is a JavaScript library for live coding music.

Installation

cargo install strudel-of-lilypond

Usage

strudel-of-lilypond input.ly    # Creates input.html with embedded Strudel REPL

Demo

See the demo/ directory for a complete example with:

• LilyPond source file with tab staff, drum staff, and multiple voices
• Generated Strudel REPL output
• Punchcard visualization, gain, and pan modifiers

Build from Source

cargo build          # Build the project
cargo run            # Run the converter with example input
cargo test           # Run all tests
cargo test <name>    # Run a specific test (e.g., cargo test test_parse_simple_notes)

Architecture

The codebase is a Rust library (src/lib.rs) with a CLI frontend (src/main.rs).

Data Structures

• Note - Pitched note with name, octave, accidental, duration, and MIDI number
• DrumHit - Drum sound with name (bd, hh, sn, etc.) and duration
• Staff - Either pitched (Vec<PitchedEvent>) or drums (Vec<DrumVoiceData> for simultaneous voices)
• Tempo - Beat unit and BPM from \tempo markings

LilyPondParser

Parses LilyPond notation with support for:

• Tempo (required): \tempo 4 = 120 - must be present in input
• Variable definitions (voice = { ... })
• Drum mode (drums = \drummode { ... })
• Score blocks with simultaneous staves (\score { << ... >> })
• Staff types: \new Staff, \new TabStaff, \new DrumStaff
• Drum voices: \new DrumVoice inside DrumStaff
• Repeat expansion (\repeat unfold/percent N { ... }) → Strudel !N syntax
• Bar grouping: each bar is wrapped in [...] brackets
• Multi-bar repeats include duration: [[[bar1] [bar2]]!2]@4
• Notes with accidentals (is/es), octave markers ('/,), and durations
• Chords (<c e g>4) → Strudel [c4,e4,g4] syntax
• Punchcard visualization comments (see below)

StrudelGenerator

Generates Strudel patterns:

• generate_pitched_staff() - note("c4 d4 e4").s("piano")
• generate_drum_staff() - sound("bd hh sn hh") or stack() for multiple voices
• generate_multi() - Multiple $: patterns for simultaneous staves
• generate_html() - HTML page with embedded Strudel REPL

LilyPond Notation Quick Reference

• Tempo (required): \tempo 4 = 120 - specifies beat unit and BPM
• Note names: c d e f g a b
• Accidentals: is (sharp), es (flat) - e.g., cis = C#, des = Db
• Octave: ' raises octave, , lowers octave (middle C = c')
• Duration: number after note (4 = quarter, 8 = eighth, 2 = half, 1 = whole)
• Rests: r → ~, r2 → ~ ~ (half rest = two quarter rests)
• Bar lines (|) define bar groupings in output
• Durations: whole=@4, half=@2, quarter=(none), eighth=@0.5, sixteenth=@0.25

Strudel Modifiers

Add special comments inside a staff or voice to control Strudel output:

• % @strudel-of-lilypond@ <color> punchcard - Enable punchcard visualization with color
• % @strudel-of-lilypond@ gain <value> - Set gain/volume (supports patterns like <0.5 1 1.5>)
• % @strudel-of-lilypond@ pan <value> - Set stereo panning (supports patterns like <0 .5 1>)

\tempo 4 = 60

\new TabStaff {
  % @strudel-of-lilypond@ red punchcard
  % @strudel-of-lilypond@ gain 2
  % @strudel-of-lilypond@ pan 0.25
  \voicea
}

\new DrumStaff {
  <<
    \new DrumVoice {
      % @strudel-of-lilypond@ cyan punchcard
      % @strudel-of-lilypond@ pan <0 .5 1>
      \kicks
    }
    \new DrumVoice {
      \hats
    }
  >>
}

This generates Strudel code with the specified modifiers:

const tempo = 60;

$: note("[c4 d4 e4]")
.gain(2)
.pan(0.25)
.color("red")
._punchcard()
  .s("piano")
  .cpm(tempo/4/1)

$: stack(
  sound("[[bd bd]]!2")
  .pan("<0 .5 1>")
  .color("cyan")
  ._punchcard(),
  sound("[[hh@0.5 hh@0.5 hh@0.5 hh@0.5]]!2"),
)
  .cpm(tempo/4/2)

Output Format

• Each bar is wrapped in [...] brackets
• Repeats use !N syntax: [[bar content]]!3
• Multi-bar repeats include total duration: [[[bar1] [bar2]]!2]@4
• CPM is calculated as tempo/4/number_of_bars
• The tempo constant is defined at the top of the generated code