Strudel

Strudel

Reference skill for programming music with Strudel — a JavaScript live-coding environment based on TidalCycles patterns, running in-browser.

Core Concepts

Cycle — the fundamental time unit (~2 seconds at the default 30 cpm). All events fit within cycles; adding events makes each shorter, not the total longer. One cycle = one bar of 4/4 at the default tempo.

Pattern — a pure function from time to events. Everything is a pattern. Transforming a pattern wraps it; the original is unchanged.

Mini-notation — a DSL written inside "double quotes" (single-line) or `backticks` (multi-line). Single quotes '...' are plain JS strings and are NOT parsed as patterns.

Chaining — methods chain left-to-right: note("c e g").s("piano").lpf(800).room(0.4).

$: tracks — the REPL syntax for parallel patterns. Each $: line is an independent stream. _$: mutes a track. Outside the REPL, use stack(...).

Quick Start

// First sound
s("bd sd hh cp")

// First note
note("c3 e3 g3 a3").s("piano")

// Stack drum + melody
stack(
  s("bd*4, ~ cp ~ cp, hh*8"),
  note("<c3 eb3 g3 bb3>/4").s("piano").room(0.4)
)

// Set BPM (default = 120 BPM in 4/4)
setcpm(120 / 4)   // cycles per minute = BPM ÷ beats-per-cycle

BPM Quick Reference

setcpm(120 / 4)   // 120 BPM, 4/4
setcpm(128 / 4)   // house
setcpm(135 / 4)   // techno
setcpm(174 / 4)   // drum and bass
setCps(140/60/4)  // cycles-per-second form

Keyboard Shortcuts (REPL)

Key	Action
Ctrl+Enter	Evaluate / update pattern
Ctrl+.	Stop all patterns

Reference Files

Pull these when you need detail:

File	Contents
references/mini-notation.md	Complete DSL syntax — all operators, euclidean, alternation, polyrhythm
references/pattern-functions.md	All pattern combinators — time, conditional, random, accumulation, signals, stepwise
references/sound-sources.md	Synths, drum banks, GM samples, FM synthesis, samples loading, MIDI/OSC
references/audio-effects.md	Full effects chain — filters, ADSR, envelopes, delay, reverb, phaser, distortion, sidechain
references/tonal.md	Scale/chord/voicing API, transposition, xenharmonic
references/recipes.md	Production idioms — beats, bass, arpeggios, chord progressions, house/techno/D&B/trap
references/visual-feedback.md	Visualizers (pianoroll, scope, spectrum, spiral) — what each shows and when to suggest them

Workflow

1. Start with sound — identify what you're building (drum beat, melody, chord progression, full track).
2. Reach for the right reference — use the table above. Most questions hit mini-notation or pattern-functions.
3. Layer with stack() — combine independent streams.
4. Automate with signals — use sine, rand, perlin for LFOs and continuous modulation.
5. Add structure — use every, sometimes, chunk, arrange for variation over time.
6. Add visualizers, especially in educational contexts — default to pianoroll(), scope(), or spectrum() when explaining or teaching. See references/visual-feedback.md for when each applies.

Common Gotchas

• Mini-notation only parses inside "..." or `...` — not '...'.
• Adding more events to a pattern makes each event shorter, not the cycle longer.
• <a b c> alternates one element per cycle (3 cycles to complete) — the whole pattern isn't faster.
• delay feedback ≥ 1 creates an infinite loop; keep it < 1.
• Reverb roomsize is expensive to change while running; set it once.
• .orbit(n) — each orbit has its own shared delay/reverb bus. Default orbit = 1.