MusaLCEClientForVSCode

Visual Studio Code extension that acts as a REPL client for any Musa-DSL REPL live coding session.

Send selected code (or the current line) from VSCode to a running Musa::REPL server over TCP, watch the server's responses and errors stream into a side panel. The extension is REPL-agnostic — it works with any server that speaks the Musa REPL line protocol on localhost:1327.

Two ways to use it

1) Standalone — bring your own REPL

You build your own main.rb (sequencer, voices, clock, transport, scale) and start the REPL yourself inside the sequencer's DSL context:

require 'musa-dsl'
require 'midi-communications'

include Musa::All

output = MIDICommunications::Output.gets
clock = Musa::Clock::TimerClock.new(bpm: 120, ticks_per_beat: 24)
transport = Musa::Transport::Transport.new(clock, 4, 24)
voices = Musa::MIDIVoices.new(sequencer: transport.sequencer, output: output, channels: [0])

transport.sequencer.with do
  # ... define helpers, scales, patterns ...

  Musa::REPL::REPL.new(binding)   # opens TCP/1327 in this DSL context
end

transport.start

Run ruby main.rb, then connect from VSCode. Maximum control; you wire MIDI, voices, clock and any custom DSL helpers yourself. See musadsl-demo/_demo-13-live-coding for a complete worked example (Tidal-Cycles-style d(n), hush, solo API).

2) Via musalce-server suite — the suite handles REPL + DAW

Install and run the musalce-server gem:

gem install musalce-server
musalce-server bitwig    # or: musalce-server live

The server boots the REPL, the sequencer, the DAW handler and exposes daw.* (e.g. daw.tracks, daw.transport, daw.surface) in the DSL context for you. Requires the matching DAW-side extension running:

• MusaLCEforBitwig for Bitwig Studio
• MusaLCEforLive for Ableton Live

See the musalce-server README for the full Quick Start and the daw.* REPL commands reference.

Which one should I use?

Use case 1 (standalone)	Use case 2 (suite)
You want full control over MIDI/clock/voices	You want the DAW connection ready out of the box
You're driving SuperCollider, Max/MSP, OSC apps, the say voice, etc.	You're driving Bitwig or Live
You're prototyping a personal live-coding DSL	You want a Stream Deck wired into your score via Pulso's MusaLCE Surface integration (Bitwig only today)

Both workflows use the same VSCode extension. The extension does not know or care which server is on the other end.

Install

From the VSCode Marketplace (recommended)

The extension is published as javier-sy.musa-lce-client-for-vscode. Install in one line:

code --install-extension javier-sy.musa-lce-client-for-vscode

Or search for "Musa-DSL Live Coding" in the Extensions sidebar inside VSCode.

From source (for development)

If you're hacking on the extension itself or want to install an unreleased build:

cd MusaLCEClientForVSCode
npm install
npm run compile
npx @vscode/vsce package       # produces musa-lce-client-for-vscode-<version>.vsix
code --install-extension musa-lce-client-for-vscode-*.vsix

Or open the project in VSCode and press F5 to launch an Extension Development Host with the extension loaded from the current source.

Keybindings

Shortcut	Command	What it does
Ctrl+Alt+Enter	MusaLCE: send	Sends the current selection to the server. If nothing is selected, sends the current line.
Ctrl+Alt+M	MusaLCE: toggle results	Shows / hides the MusaLCE status panel.

Both commands are also available in the command palette, the editor context menu and the editor title bar.

Status panel

The status panel renders the server's responses live as the sequencer executes. It distinguishes four kinds of message coming back from the server, following the line protocol documented in musa-dsl/docs/subsystems/repl.md:

• //echo … //end — code about to be executed, echoed back so you can confirm what landed.
• Plain lines (anything not prefixed with //) — Ruby puts output, sequencer log lines, return values.
• //error … //backtrace … //end — raised exceptions with backtrace.
• Future responses from work that develops in time (events scheduled with at, every, play, etc.) keep arriving as the sequencer runs.

Configuration

The extension connects to localhost:1327 by default. There is currently no VSCode setting to change the host or port — the connection target is fixed in src/connection.ts (lines 13-15). If you need to connect to a remote or non-default server, edit those defaults and rebuild, or pass host / port to the Connection constructor in src/extension.ts.

This will likely be exposed as a proper VSCode setting in a future release.

Internal commands

Selections beginning with #% are treated as internal extension commands rather than Ruby code: they are eval-ed against the extension's commands object and never reach the server. These are intended for advanced/diagnostic use and are not part of the user-facing API. Avoid lines starting with #% in production scores.

Troubleshooting

Symptom	Likely cause
Status panel shows "Error on connection … (Error: connect ECONNREFUSED)"	No Musa::REPL server is running on localhost:1327. Start one (either case 1 or case 2 above) and use MusaLCE: toggle results twice to reconnect.
Status panel shows code echoes but no output	The server is connected, but the Ruby code has no puts and no return value worth displaying. Add puts something to verify.
Need to point at a non-default host/port	See Configuration above — currently requires editing connection.ts.

Author

Javier Sánchez Yeste

License

MusaLCEClientForVSCode Copyright (c) 2021-2026 Javier Sánchez Yeste, licensed under GPL 3.0 License.