Rustel: live-code music in your terminal

Install

macOS Linux / WSL Windows

curl -L https://rustel.cc/install | bash && rustelup

Apple Silicon. Open a new terminal, then run rustel studio.

curl -L https://rustel.cc/install | bash && rustelup

x86_64. Open a new terminal, then run rustel studio.

irm https://rustel.cc/install.ps1 | iex

x86_64, in PowerShell. Open a new terminal, then run rustelup. Then run rustel studio.

rustelup installs into ~/.rustel/bin. On Windows that folder is %USERPROFILE%\.rustel\bin. Run rustelup again to refresh, or rustelup --version v0.3.0 to pin a build. To build from source, follow the readme.

What you get

Strudel patterns: Patterns, samples, synths, and effects from the Strudel language. Supported unless listed in the compatibility docs.
Native extensions: Standard builds ship extensions from Switch Angel and undefined_aeon. More extensions from other Strudel artists will land natively over time.
Sound checks: Selected scores render in both engines. Waveforms are compared offline for fixed scores, assets, and settings.
Studio: Terminal editor with live update, visuals, a mixer, and a key reference. A bad update leaves the last good score playing.
Your editor: Run rustel song.strudel --watch and edit in your favorite editor. Audio keeps running across saves. Or use the rustel-neovim plugin to drive the engine from Neovim.
Session tapes: Each installed update is logged with time. Your jam stays on disk. No arm step. No extra save ritual.
Hardware out: Speakers, MIDI, OSC, or serial from the score.
Offline render: Bounce to WAV or MP3. Same score, assets, and settings on one machine give repeatable output.
Audio thread: Rational cycle math, a native mini-notation parser, and a DSP graph with no allocation on the audio path. SIMD kernels follow your CPU. Low CPU and memory in live play. An error mutes one cycle of one pattern. The clock keeps going.

The studio

Press Ctrl+Enter to update. Same chord as strudel.cc. The piano roll and the scope follow the pattern.

Ctrl+Enter: Update and play. Strudel's update chord. A bad update leaves the last good score playing. Ctrl+. stops.
keyboard: Everything is reachable from the keyboard. The mouse works too. Keyboard-only is the easier grip in a live set.
beat: The sounding step lights in your source. The header dot pulses on the downbeat.
Ctrl+D: Open the reference. Every function in the language, inside the editor.
visuals: Piano roll, punchcard, scope, and spectrum as rows in the editor, plus a mixer and a minimap.
editor: Modeless. Selection, undo, redo, bracketed paste. Saves stay off the audio thread.

In the studio

Widgets

Shift+F1 opens a dock of widgets beside the score. Add a scope, a spectrum, a vectorscope, or the event list. Press a to add one. The pictures move with the music.

Themes

Ctrl+T opens the theme list. Arrow to a theme and press Enter. Themes can be customize and also supports hydra backgrounds.

Session tapes

The first successful update opens a tape beside the set. Each installed score is stored with its time. The tape keeps the score and the timing, not the audio. Open it from the set panel, or replay it from the shell.

$ rustel replay tonight.rustel-session

$ rustel replay tonight.rustel-session --from 600

Add --from 600 to start ten minutes in. For sound on disk, record a take or export a bounce.

Samples

Ctrl+F, then Tab, opens the sample list. Right expands a bank. Space previews the sound. Enter copies the name into the score. Drop an audio file on the Studio window to import it.

Chords and scales

Chords and scales are the next two tabs. Each row draws its notes on a keyboard. Right opens the row. Space plays the chord or the scale. The keys light while it sounds.

Reference

Ctrl+D opens the word under the caret. Ctrl+F browses the whole list. Type to search. Enter inserts the example.

Visuals

_pianoroll(), _scope(), _spectrum(), _punchcard(), and the rest draw inside the score. The playhead moves with the clock.

Generator and examples

The generator tab builds a part from a handful of sliders. Press c to copy the code, then paste it into the editor. The examples tab holds grooves, tracks, and Hydra sketches. Enter puts an example into the score.

Mixer

F4 opens the mixer. The master and each orbit have a meter and a fader. Ctrl+Shift+Up and Ctrl+Shift+Down move the master.

Limiter

Open Transport, then Add limiter to set. A brickwall sits on the master. The mixer strip sets the ceiling. Press c to cycle the character. Press b to bypass. .limit() in the score does the same job. The set keeps the limiter.

Settings

Ctrl+O opens settings. Playback, look, samples, controllers, and key bindings are in there. Tab changes page.

Syntax check

Studio checks the score as you write. A pause after typing stops, and a bad call is underlined. The header counts the problems. The footer names the first one, often with a suggestion.

Settings, then syntax check, picks the mode. full marks errors while you type. That is the default. on update marks them only when an update is refused. off leaves the editor unmarked. An update still refuses a bad score, and the footer and the log still say why.

Mapping

Tab to Mapping on the settings sheet. Twelve slots sit in a grid. Enter on a slot, then move a MIDI knob, a fader, or a stick. That control drives the matching slider.

Ctrl+L learns a pad for the scene you are on. Hit the pad. That pad launches the scene, the way a Maschine Mk3 pad fires a sound. Launch on, at the top of Settings, chooses the line it waits for. Off means the scene starts now. Beat, cycle, or a phrase waits.

Rewind update is Ctrl+Shift+S. The scene plays from cycle zero. Ctrl+Shift+U keeps rewind on that scene, so every launch starts there.

Split

Ctrl+E splits the editor. The other pane opens the next scene. With one scene in the set, Ctrl+E makes the second. F10 moves the caret across. You edit both.

Update the pane you want to hear. Ctrl+Enter and F5 both do that. The title marks the sounding scene. Hop to the other pane and update, and that scene takes the sound. Ctrl+E again closes the split. Both scenes stay in the set.

Hydra

await initHydra(), then a chain that ends in .out(), draws behind the code. The picture follows the score. Visuals opacity in Settings sets the strength of the picture.

Record a take

Shift+F11 records the master mix. The minimap stays on at the right edge. The header shows the running take. Press the chord again to finish. Studio writes a 24-bit WAV into the set.

Export

The visuals dock sits across the top, with the set name in ASCII and the mixer orbits under it. Ctrl+Shift+X exports the focused scene. Choose a length in cycles, or run until the sound falls quiet. Pick wav or mp3. The limiter can ride along. Enter writes the file.

Transport, then Reveal last export or take, opens that file's folder. A take is the live master. Export renders the scene to a file.

Record a sample

Ctrl+H records from your microphone or voice. Press it again to finish. The take lands in the recordings bank, ready to use right away. Ctrl+J pastes the name into the score. Chop that line, then update, and the slice plays.

Sliders

Ctrl+J on a number offers to make a slider. After you update, the fader sits in the score. Every slider in the score also shows up on the mixer, so you can reach them without scrolling the score.

The command line

Run the engine from a shell. Watch a file. Bounce a render. Query a cycle. Open Studio.

# play and reload on each stable save
$ rustel song.strudel --watch

# bounce a render
$ rustel render song.strudel -o take.wav --format scalar-wav --duration 60

# check a score without sound
$ rustel check song.strudel

# replay a jam from its session tape
$ rustel replay tonight.rustel-session

# list audio and MIDI devices
$ rustel devices

# print one cycle as JSON
$ rustel query -e 'note("c e g").s("piano")' --json

# install shell completion
$ rustel completions --install

# open Studio on your last set (creates one on first use)
$ rustel studio

# open a score file (starter score if the path is new)
$ rustel studio song.strudel

# open a set folder
$ rustel studio set/

Neovim

The rustel-neovim plugin plays the buffer you have open. Syntax colors the score. Active notes light up as they sound. Scope, piano roll, spectrum, and spiral draw in the buffer.

Neovim 0.9 or newer, and rustel on your PATH. Ctrl+Enter updates. Ctrl+. stops

Under the hood

Rust schedules patterns and runs DSP. Sandboxed QuickJS evaluates Strudel JavaScript. Ratatui draws Studio. DSP kernels pick SIMD paths from your CPU for low CPU and memory use. rustel doctor and Studio's About panel show the active kernels.

Terminal setup and known limits

Pick a capable terminal: Full colour, Unicode, and enhanced keyboard input help Studio. Start with Ghostty or iTerm2 on macOS. On Linux try kitty, Ghostty, WezTerm, or foot. On Windows use Windows Terminal. Studio adapts to what your terminal reports.
Check your shortcuts: Ctrl+Enter updates. Ctrl+. stops. Same chords as strudel.cc. If your terminal blocks those, use Ctrl+S / F5 and Ctrl+G / F8. Open Settings → Keybinds to view or change bindings. On macOS use Control. Command works only when the terminal forwards Command.
Expect display differences: Fine glyphs and pixel graphics need terminal support. Studio falls back to cell graphics. The bare Linux console has weak colour, glyph, and shortcut support. Use a graphical terminal such as foot there.

The Studio guide covers terminal profiles, keyboard fallbacks, and graphics modes.