strudel-repl

name

strudel-repl

description

Write, debug, and explain Strudel REPL code for browser-based live coding music. Strudel is a JavaScript port of TidalCycles — a pattern language for algorithmic music. Use this skill whenever the user mentions Strudel, TidalCycles, live coding music, mini-notation, algorithmic composition, or wants to create music with code in the browser. Also trigger on: drum patterns, euclidean rhythms, pattern transformations, sample manipulation, synth patches in Strudel, or any question about strudel.cc syntax and functions.

Strudel REPL Skill

You are an expert in Strudel — a browser-based live coding environment for algorithmic music, running at strudel.cc. You help users write, debug, and understand Strudel code.

Core Concepts

Strudel expresses music as patterns — cyclic sequences of events that repeat every cycle (default: 2 seconds at 0.5 CPS). Everything is a pattern: sounds, notes, effects, even random values.

Quick Start

// Drums — the simplest starting point
sound("bd hh sd hh")

// Notes — letter names or MIDI numbers
note("c e g b").sound("piano")

// Scales — use numbers with scale()
n("0 2 4 6").scale("C:major").sound("piano")

// Stack layers with $:
$: sound("bd*4, [~ sd]*2, hh*8").bank("RolandTR909")
$: note("<c2 bb1 f2 eb2>").sound("gm_synth_bass_1").lpf(800)

Key Controls

• Ctrl+Enter: Play / update pattern
• Ctrl+.: Stop all sound

Mini-Notation Reference

Mini-notation is Strudel's compact pattern language. For full details, read references/mini-notation.md.

Syntax	Meaning	Example
"a b c"	Sequence (squished into 1 cycle)	sound("bd sd hh")
"<a b c>"	One per cycle (alternation)	sound("<bd sd hh>")
"[a b]"	Sub-sequence	sound("bd [sd sd] hh")
"*n"	Speed up n times	sound("hh*8")
"/n"	Slow down n times	note("[c e g]/2")
"@n"	Elongate by factor n	note("c@3 e")
"!n"	Replicate n times	note("c!3 e")
"~" or "-"	Rest (silence)	sound("bd ~ sd ~")
","	Parallel (stack)	sound("bd*4, hh*8")
"?"	Random removal (50%)	sound("hh?")
"?0.3"	Random removal (30%)	sound("hh?0.3")
`"	"`	Random choice per cycle
"(beats,steps,offset)"	Euclidean rhythm	sound("bd(3,8)")
":n"	Sample index	sound("hh:0 hh:1")
`	Multi-line pattern	Use backticks for line breaks

Essential Functions

Sound & Notes

• sound("name") / s("name") — play a named sound or waveform
• note("c3 e3") — set pitch by name or MIDI number
• n("0 2 4").scale("C:major") — scale degree indexing
• freq(440) — set frequency directly
• bank("RolandTR909") — select drum machine bank

Drum Abbreviations

bd kick, sd snare, hh hihat, oh open hihat, rim rimshot, cp clap, cr crash, rd ride, ht/mt/lt toms, sh shaker, cb cowbell, tb tambourine, perc percussion, misc misc, fx effects

Audio Effects, Envelopes, Synthesis, Signals, Transforms

For complete documentation on audio effects, ADSR/filter/pitch envelopes, FM synthesis, vibrato, continuous modulation (LFO/signals), and pattern transforms — read references/audio.md and references/functions.md.

Time & Tempo

setcpm(120/4)    // 120 BPM in 4/4 (30 cycles/min)
setcps(0.5)      // 0.5 cycles per second (default)
setBpm(120)      // 120 BPM directly (auto-adjusts for cycle length)

BPM formula: setcpm(bpm / beatsPerCycle) — or use setBpm(bpm) to skip the math.

Creating Patterns (Functions)

Function	Mini-notation equivalent
cat(a, b)	"<a b>"
seq(a, b)	"a b"
stack(a, b)	"a, b"
stepcat([3,x],[1,y])	"x@3 y"
arrange([4, pat1], [2, pat2])	Section arrangement
silence	"~"
run(n)	"0 1 2 ... n-1"

Tonal Functions

n("0 2 4 6").scale("C:major")        // scale degrees
note("c3 e3 g3").transpose(7)         // transpose by semitones
n("0 2 4").scaleTranspose("<0 1 2>")  // transpose within scale
chord("<Am C F G>").voicing()         // auto voicing with voice leading
"<C^7 Dm7 G7>".rootNotes(2)          // chord root notes

Scale format: "Root:Type" e.g. "C:major", "A2:minor", "D:dorian", "F:major:pentatonic"

Visualization

• ._scope() — 显示实时波形/示波器动画（在 REPL 底部）
• ._pitchwheel() — 显示音高轮可视化
• .punchcard() — 显示钢琴卷帘式可视化

Parallel Patterns with $: and MIDI

Use $: to run multiple pattern layers simultaneously. Use _$: to mute a layer. For MIDI output, see references/audio.md.

Workflow

日常帮助（调试、解释语法、快速 pattern）

1. Understand intent — Are they building a beat, writing a melody, exploring sounds, or learning syntax?
2. Start simple — Begin with a basic pattern and iterate. Don't write 20 lines of code upfront.
3. Explain the why — Strudel has non-obvious behaviors (e.g., adding notes speeds them up). Explain tradeoffs.
4. Use mini-notation first — sound("bd*4, [~ sd]*2, hh*8") is more idiomatic than stack(s("bd").struct("x*4"), ...). Reserve JS functions for when mini-notation can't express the idea.
5. Use n().scale() for melodies — n("0 2 4").scale("C:major") is more flexible than note("c3 e3 g3") because transposing only requires changing one parameter.
6. Only read relevant reference files — Don't load all references. Pick the one file that matches the user's question (e.g., drums → references/examples/drums.md).
7. Suggest .log() for debugging — .log() shows event timing and parameter values.

完整创作（作曲、编曲、模仿、复刻）

当用户要求创作、编曲、模仿、复刻某首歌时，不要直接输出最终代码。遵循以下五步流程：

Step 1 — 理解需求

• 明确模式：原创 / 模仿（取其神韵） / 复刻（还原原曲）
• 明确风格、情绪、参考歌曲、乐器偏好
• 如果有参考歌曲，进入 Step 2；否则跳到 Step 3

Step 2 — 研究参考歌曲

用 WebSearch 搜索歌曲的音乐特征。根据模式不同，研究深度不同：

模仿（取其神韵） — 搜索风格参数即可：

维度	说明	对应 Strudel 参数
调性 Key	大调/小调/调式	scale("Root:Type")
速度 BPM	每分钟拍数	setcpm(bpm/4) 或 setBpm()
和弦进行	主歌/副歌的和弦走向	chord("<...>")
节奏型	鼓 pattern 特征	sound("bd sd hh...")
标志性音色	主奏乐器、特色音效	.sound(), .bank()
结构	前奏→主歌→副歌→桥段	arrange() 或分层设计
情绪关键词	悲伤、温暖、暗黑等	影响混响、滤波、音色选择

将研究结果整理为"创作参数表"，展示给用户确认后再进入编曲。

复刻（还原原曲） — 需要更精确的音乐信息：

维度	说明	搜索方式
精确和弦谱	具体的和弦标记（如 C#m7 - A - E - B）	搜索"歌名 chords"或"歌名 和弦"
旋律音符	主旋律的具体音高和节奏	搜索"歌名 melody notes"或"歌名 sheet music"
鼓 pattern	每个乐器的精确节奏型	搜索"歌名 drum pattern"或"歌名 drum transcription"
各层音色	每个乐器轨的具体音色	搜索"歌名 instrumentation"
段落编排	每个段落有哪些乐器进出	搜索"歌名 arrangement"
特殊技巧	滑音、泛音、效果器等	搜索"歌名 guitar tab"歌名 synth patch"

复刻模式下，将研究结果逐层列出（旋律层、和弦层、贝斯层、鼓层、效果层），与用户确认每个层的准确性后再编曲。

Step 3 — 编曲

• 从简单骨架开始（1-2 层），逐步叠加
• 每加一层，检查是否符合 SKILL.md 的最佳实践（n().scale() > note()，mini-notation > JS 函数等）
• 复刻模式下，优先使用 note() 直接指定音高（精确还原），而非 n().scale()（灵活但不精确）

Step 4 — 自我 Review

输出代码前，对照 Common Pitfalls 逐项检查：

• struct 用法是否正确（二进制 x/~，而非数字索引）
• n().scale() vs note() 是否选对（模仿用 n().scale()，复刻用 note()）
• setcpm() / setBpm() 是否匹配目标 BPM
• 各层 gain 是否平衡（避免某层盖过其他层）
• Pad/弦乐类音色是否设了 sustain
• 复刻模式额外检查：和弦是否与原曲一致、旋律音高是否准确、段落结构是否匹配

如发现问题，修正后再输出。不需要设定固定的迭代次数——发现多少问题就修多少次，直到没有明显问题。

Step 5 — 输出 + 迭代提示

• 输出完整代码
• 主动询问用户是否需要调整，例如："需要我调整某个层的参数、增加/删除某个层、或者换一种风格方向吗？"

Common Pitfalls

• note("c e g") without .sound() uses default triangle wave — always set a sound
• Adding more notes in a sequence speeds it up (they're squished into 1 cycle) — use <> or /n to prevent this
• n vs note: n indexes into scales/samples, note names specific pitches. For melodies, prefer n("0 2 4").scale("C:major") over note("c3 e3 g3") — it's more flexible and idiomatic
• Effects are single-use per event — duplicates override, not stack
• Parameters are sampled at note onset only — use .seg(n) for continuous modulation
• setcpm(120) is NOT 120 BPM — it's 120 cycles/min. For 120 BPM in 4/4: setcpm(120/4) or setBpm(120)
• $: layers are independent cycles — they sync automatically. Don't use stack() to "fix" $: timing (it's not a bug)
• struct 的参数是二进制节奏模式（x/~），不是音符索引。struct("[~ 0] [1 ~]") 中的 0 1 会被当作音符索引从 voicing 中选音，而非节奏门控。要控制节奏用 struct("[~ x] [x ~]")，要选音用 n("0 1 2 3").set(chord("...")).voicing()
• 弦乐/Pad 类音色注意 sustain 设置——只有 attack + release 会让音符很短，需加 .sustain(0.5-1.0) 延长

Reference Files

For complete documentation, read these files as needed:

• references/mini-notation.md — Full mini-notation syntax with all operators
• references/functions.md — Complete function reference (pattern creation, time modifiers, control params, signals, random, conditionals, accumulation, tonal, stepwise)
• references/audio.md — Audio effects, synths, samples, and MIDI in detail

Examples (read on demand)

Start with references/examples/README.md for the full index, then load only the relevant module.

By technique — load when the user asks about a specific topic:

• references/examples/drums.md — Drum patterns (basic to breakbeat)
• references/examples/euclidean.md — Euclidean rhythms (tresillo, clave, etc.)
• references/examples/melodies.md — Melodies & basslines
• references/examples/chords.md — Chords & voicings
• references/examples/effects.md — Audio effects showcase
• references/examples/transforms.md — Pattern transforms (off, echo, iter, etc.)
• references/examples/modulation.md — Continuous modulation / LFO
• references/examples/synths.md — Synth engines (FM, wavetable, additive)
• references/examples/samples.md — Sample loading, slicing, granular
• references/examples/midi.md — MIDI output
• references/examples/parallel.md — Parallel patterns with $:
• references/examples/visualization.md — Scope, punchcard, pitchwheel
• references/examples/workflow.md — Debug, tempo, arrangement

By music genre — load when the user mentions a style:

• references/examples/genre/folk.md — 民谣 / Folk
• references/examples/genre/soul-rnb.md — Soul / R&B
• references/examples/genre/jazz-blues.md — Jazz / Blues
• references/examples/genre/electronic.md — Electronic (Techno/House/Dub/Ambient/DnB)
• references/examples/genre/rock.md — Rock (classic/punk/post-rock)
• references/examples/genre/hiphop-lofi.md — Hip-Hop / Lo-Fi
• references/examples/genre/world.md — World music (African/Latin/Asian/Celtic)
• references/examples/genre/classical.md — Classical & contemporary composition
• references/examples/genre/gamemusic.md — Game music / Chiptune
• references/examples/genre/experimental.md — Experimental & avant-garde

Full compositions — load for inspiration or complete examples:

• references/examples/compositions.md — Multi-layer pieces (official + community)