macdesk

A macOS-style desktop that runs Go apps you install at runtime — an App Store, a dock, windows, a menu bar, and small apps (calculator, countdown, snake, sudoku) written against a tiny declarative view API.

macdesk is a demo built on MyGo (native UI) and yaegi (Go interpreter). The desktop is compiled Go; the apps are .goapp packages interpreted inside a sandbox, so installs need no compiler and no restart.

The look — glass dock, 25 DIP menu bar, 11 DIP windows, traffic lights, and the whole icon set — follows StarKnightt/macos-web: its design tokens and its 127 SVG icons are rendered by MyGo's own SVG engine at any size.

The Finder: a sidebar of places, a search field, and an icon view that reflows from three columns to nine as the window grows, with the item count in its status bar:

Light appearance, same tokens and icons:

All 127 icons: app artwork, glyphs and file icons, drawn from one set:

App Store

The dock's cart opens the store: installed apps, installable samples, an import field, and install/open/uninstall buttons. Installing copies the package into ./apps/<id>/<version>/, opening runs it, uninstalling deletes it.

An installed app runs in its own window and lives in the dock:

The rest of the desktop

Launchpad (F4 or the dock grid) blurs the desktop behind every installed app and filters as you type:

Spotlight (⌘Space or the menu-bar lens) searches apps, actions and files, arrows move, Enter runs:

Notification Centre (menu-bar toggle) holds the clock, the week strip, the weather and the app events:

Settings pick the appearance, one of five wallpapers and one of seven accent tones, live:

Safari, Mail, Photos, Music and Terminal open from the dock with the same chrome — a start page of favourites, a mailbox list, a photo grid, a player and a shell transcript:

Right-clicking the desktop opens New Folder / Wallpaper / Launchpad / Spotlight / Empty Trash / About; right-clicking a dock icon opens Open / Close Window / Quit. The trash keeps what you uninstall, and the dock shows it full.

Quick start

go run .          # or: go build -o macdesk . && ./macdesk

Requires Go 1.27+. Installed apps live in ./apps/ (git-ignored). Delete that folder to start clean.

Writing an app

An app is a folder (or a zip) with manifest.json and main.go, at most 2 MiB:

{"id": "countdown", "name": "Countdown", "version": "1.0.0", "api": 1, "permissions": ["timer"]}

Field	Rules
id	[a-z0-9-]{1,32}, also the storage folder
name	shown in the store, the window title and the dock
version	three numeric segments, 1.0.0
api	must be 1
entry	source file, default main.go
icon	optional name from the bundled set, e.g. app-calculator; see appicons/svg/
permissions	timer for After, storage for the storage calls

main.go exports four hooks:

package main

import (
	"strconv"

	"appkit"
)

type state struct{ left int }

func Open() any { return &state{left: 60} }

func View(s any) *appkit.Node {
	st := s.(*state)
	return appkit.Column(8,
		appkit.Text("seconds left: "+strconv.Itoa(st.left), "title"),
		appkit.Button("start", map[string]any{"type": "start"}, true),
	)
}

func Action(s any, a map[string]any) any {
	st := s.(*state)
	if a["type"] == "start" {
		st.left = 60
	}
	return s
}

func Close() {} // optional

View returns a tree of nodes the host renders; Action receives {"type": "tick"} for timers and touches, slider, checkbox and input events, and returns the state to keep. See sampleapps/ for four complete apps.

appkit

Call	What it makes
Column(gap, children...) / Row(gap, children...)	vertical / horizontal stack, gap in 4 DIP units
Text(text, size)	title, title bold, body, caption
Button(label, action, primary)	sends action when clicked
Input(value, placeholder, action)	one line, sends {"text": value}
Image(lucideName, size)	Lucide icon
Progress(value, max) / Slider(value, min, max, action) / Checkbox(label, checked, action)	values send {"value"} / {"checked"}
Box(color, children...)	tinted container, or a small tile when empty
StorageGet / StoragePut / StorageDel	per-app key-value JSON, needs storage

Imports are limited to appkit plus strconv, strings, math, math/rand and sort. There are no goroutines, files or network: with the timer permission the host calls Action with {"type": "tick"} about once a second.

Pitfalls when writing apps

• Keep state in a struct pointer (Open returns &state{}). Mixing booleans and maps trips the interpreter.
• Read map values into a local before a switch or if; do not branch on an indexed expression directly.
• Assign Children instead of building huge variadic calls when a row is dynamic.

How it works

manifest + main.go  ──yaegi──▶  hooks  ──View()──▶  Node tree  ──render──▶  MyGo widgets
        │                          ▲                    │
        └── apps/<id>/<version>/   └──Action(evt)───────┘

• apphost.go compiles app source in a sandboxed interpreter, validates hooks, and calls them with a timeout.
• appkit.go is the node API and its interpreter symbol table; viewtree.go renders nodes with MyGo widgets.
• installer.go validates manifests and installs, imports (folder or zip) and prunes old versions.
• appstore.go is the store UI; theme.go holds the palettes, the wallpapers and the desktop metrics.
• launchpad.go, spotlight.go, notifications.go, settings.go, trash.go and deskmenu.go are the desktop overlays; appwindows.go holds the built-in windows; desk.go owns the state they read and menubar.go the menu bar.
• appicons/ embeds the set: svg/ is generated from macos-web's sheet by tools/extract_icons.go, custom/ holds the hand-drawn and text-free redraws that win on a shared name.
• Widgets (desktop/, display/, layout/, typography/, icon/, sound/, kit/) come from CrychicUI.

Tests

go vet ./... && go test ./...

The suite drives MyGo's tester: it installs samples, ticks timers, clicks cells, walks the interpreter's state and checks the store flow end to end. MACDESK_SHOTS=1 go test -run 'TestShoot' . refreshes docs/*.png.

Credits

• StarKnightt/macos-web for the icon set under appicons/svg/, the design tokens the palette here follows, and the squircle outline of the app icons. MIT.
• MyGo for the native UI and its SVG renderer, and yaegi for the interpreter.
• Lucide icons for the remaining glyphs, and CrychicUI for the macOS-flavoured widgets.

MIT licensed, see LICENSE.