Develop generators live in Emacs (Sly)

Gloopy keeps a resident Lisp kernel running to generate your script clips. That kernel also hosts a Slynk server, so you can attach Emacs (via Sly) to the very image that makes your music — redefine a generator, re-run the clip, and hear the change without a restart. Once connected, clicking a script clip in Gloopy opens its source right here in Emacs.

Prerequisites

• SBCL installed. Gloopy starts the warm kernel automatically when it finds sbcl on the PATH; a green λ Slynk port indicator appears in the status bar once it's ready. (Set GLOOPY_NO_KERNEL=1 to opt out.)
• Emacs with Sly installed (M-x package-install RET sly).

Set up the package

If you installed a Gloopy package, gloopy.el is in Emacs's site-lisp, so it just loads:

(require 'gloopy)

Running from a source checkout instead? Point Emacs at the emacs/ directory first:

(add-to-list 'load-path "/path/to/gloopy/emacs")
(require 'gloopy)

Connect

With Gloopy running:

M-x gloopy-connect

This reads the port Gloopy advertised, attaches Sly to the kernel, and turns on gloopy-mode. You now have a REPL on the live kernel — the prelude (note, set-generator, …) is already loaded, in the gloopy-kernel package.

You can also open the connection instructions from Gloopy itself: File → Connect Emacs to Kernel (Slynk).

The live loop

1. Open a clip's source (click the clip in Gloopy, or C-x C-f the file).
2. Edit the generator and evaluate it with C-c C-c (or C-c C-k for the whole buffer). set-generator installs it into the running kernel — it is live immediately.
3. Back in Gloopy, Generate from script on the clip (or call RegenerateClip over the control API). The kernel runs the generator as it exists in the image right now, so your just-evaluated redefinition is what runs — no save, no restart.

The kernel loads a clip's source file once (the first generate of the session); after that, the live image is authoritative, exactly as you'd expect hacking at a Lisp REPL. A clip generates its notes only when you ask it to (step 3) — editing alone doesn't change what plays until you generate (or Live-drive from script).

Hands-free: mark a clip "Live"

To skip the manual Generate entirely, right-click the clip → Live (auto-generate on playback). A LIVE badge appears on the clip. Now, while the transport is rolling, Gloopy re-runs the clip's generator from the live image about a bar before the clip plays and swaps in the fresh notes — so with a clip looping, every C-c C-c is heard on the next pass, no clicks at all. If a generate ever runs long (e.g. the very first, cold one), the clip falls back to its cached notes for that pass. Toggle it off to freeze the clip again. (Over the control API: SetClipScriptLive(track_id, index, live).)

Save to persist

Live redefinitions live in the running image, not on disk. Save the buffer (C-x C-s) when you're happy: a fresh kernel (Gloopy restart, or reopening the project) reloads the generator from the file, which is what keeps the project reproducible. Think of it the same way you would any Lisp image — the image is live, the file is the record.

How the link works

Gloopy writes a small discovery file on startup — $XDG_RUNTIME_DIR/gloopy/kernel.json (falling back to ~/.cache/gloopy/kernel.json) — with the Slynk port and the gRPC control port. gloopy-connect reads it to find the kernel.

gloopy-mode in turn advertises Emacs back to Gloopy (a presence file, emacs.json, next to the discovery file) so that clicking a script clip routes through emacsclient to gloopy-open-clip. If no connected Emacs is advertised, Edit script code falls back to launching a fresh editor.

Troubleshooting

• No λ indicator / gloopy-connect says no kernel found — SBCL isn't installed or the kernel hasn't warmed up yet. Confirm sbcl is on the PATH and give it a few seconds on first launch (the one-time proto compile).
• Clicking a clip doesn't open it in Emacs — make sure you ran gloopy-connect (it starts the Emacs server gloopy-mode needs). It routes to the Emacs that most recently connected.