const app = {
lines: document.getElementById('lines'),
textbox: createTextbox(),
lineTemplate: createLineTemplate(),

const socket = connect(

initial({ lines, uuid, charLimit }) {
app.uuid = uuid
app.charLimit = charLimit

added(line) {

removed(i) {

server.onclose = (ws) => {
if (ws.line) {
const i = lines.indexOf(ws.line)
lines.splice(i, 1)
server.sendToAll({ removed: i })

server.commands = {

begin(ws) {
const line = {
hash: ws.hash,
uuid: ws.uuid,
text: '',

ws.line = line
server.sendToAll({ added: line })

run() {
console.log(`Running on port ${this.port}`)

this.wss = new WebSocket.Server({
port: this.port,
verifyClient: this.verify.bind(this)

this.pruneInterval * 1000


Steven Degutis

Full-stack software developer for hire

Designing a macOS window manager in Racket

June 02, 2017

Back story

A few years ago, I made a simple window manager for macOS that was really useful to me. (In fact I still use it to this day.) Over the next few years, I made about 10 variants, as a way of learning various programming languages and techniques. It became my “hello world” of sorts.

Then, the small business that I worked for, which sells software training videos on a custom web store, hired a national-funeral-home executive as its new CEO. He must have decided the website was feature-complete and that it no longer needed to be maintained.

So now I’m self-employed, trying to run a business with my wife making and selling simple but quality iPhone apps, the best of which (so far!) is Quick List, the only todo app with a hidden mini-game. My job has now turned into full-time marketer, so I have no free time anymore to make stuff.

But I can still dream. And macOS window managers are still fun for me to design, even if only in my imagination.

Goals and limitations

Here’s the feature-set of my ideal window manager for macOS:

  • Minimalistic GUI
  • Feature-rich API
  • Dynamic language
  • REPL for quick & easy experimentation
  • Auto-generated documentation
  • 100% extensible through plugins
  • Not require users to install any dev environment
  • Never need to recompile core app (unless OS update requires it)

Some limitations and restrictions:

  • Must be a GUI app in order to enable “Accessibility”, the macOS feature which allows controlling windows in other apps

  • Needs a dynamic “scripting” language with good C and Objective-C bindings to truly be fully extensible without changing the core app while still having a decent and useful REPL

  • Needs to be self-contained and not require a website for it to work, esp. by containing documentation within the app

  • Must have first-class documentation (e.g. reflective) to allow plugins (GUI based?) that make it easier to browse/search docs

  • Should be created made with modules in mind to make libraries easier to create and manage, even if only through community convention

The language

After years of looking at language options, I really think Racket is the best fit for this job. It’s got everything that we need:

  • Actively developed and maintained
  • Officially maintained in-language bindings to C and Objective-C
  • Solid and full-featured standard library
  • Has a REPL for faster development of the app and plugins
  • Decently-sized and active community
  • Supports modules for clean extensibility via plugins


There would be no Objective-C or C files in the project. Everything would be written in Racket, taking advantage of the fact that you can declare bindings to C and Objective-C interfaces in Racket at runtime.

Since the only code is written in Racket, there wouldn’t be much use for Xcode. Racket comes with a command raco exe --gui myapp.rkt that builds a legit macOS app bundle.

The actual app bundle itself would mostly just be for bootstrapping the Racket environment, since all useful functionality can be written in pure Racket as plugins.

The app would use a server architecture, communicating efficiently with clients via mach ports. It would come with a companion command-line utility written in Racket that presents the user with a REPL and sends commands to the server over mach ports.

The “GUI” app would have only three simple roles:

  • Putting an icon in the status bar (next to the clock)
    • Menu item for letting you know whether accessibility is enabled (green or red orb)
    • Menu item for toggling whether to launch at login
    • Menu item for restarting (to clear state)
    • Menu item for quitting
  • Loading the ~/.myapp/init.rkt file at app-launch
  • Setting up a mach port listener for incoming commands

Developing the core app itself wouldn’t take more than a few hours, so there’s no need for a compile script or shared dev environment. Once it’s done, the init-file and REPL-client can be used for the rest of development.

To make development fly, I’d use a REPL for development, probably inside Emacs with something like geiser so that I can create and run code while interacting with live objects in real time. Using Clojure for 5 years got me hooked on this style of development.

Plugin developers wouldn’t need to install anything, because the app would come with a Racket environment built-in. In fact after the initial app server and client are compiled, I can even ditch my own Racket environment.


The core would be low-level modules that interface with the underlying Objective-C classes and C functions directly, only wrapping them with simplistic Racket facilities. This would be things like wrapping NSWindow and UIAXElement with Racket classes that delegate all real functionality to the real objects, while handling things like memory management. Basic Hotkey functionality would be here too.

On top of that we’d have mid-level modules that wrap the low-level modules, making them easier to use while still being generic. This would be things like adding methods to the window class for things like moving windows and getting their sizes and positions, and mapping the global NSScreen coordinates to monitor-specific coordinates.

Finally the top layer would be full of convenience classes to help with specific window/environment management tasks, such as having a “grid” to move windows along, or a wrapper around the plain-jane hotkeys classes that allow you to have “key chords” like in most modern editors (Sublime, Atom, Emacs, etc).

Documentation data would ideally be generated at runtime by inspecting the current runtime environment. Racket’s documentation on how to write documentation in Racket is really confusing, so I don’t know if we’d be able to utilize this or not. Either way, the goal is to have global documentation data that you can access programmatically, and even generate CLIs and GUIs to explore and search.


In the end, all these modules will be included within the app bundle, as well as the REPL client, so that the user only needs to grab a compiled copy of the app bundle from Cask or Github or wherever, and then they’d have a full-fledged environment they can start using to create an init-file with custom window management functionality that suits their preference and workflow style.


All good project names are taken. Some people suggested using UUIDs but they’re hard to remember. I think we have to start using numbers, but with a prefix to make it friendly to almost all software ever, which usually doesn’t allow things to be named starting with a number. Since I’m the first person to do this, this app gets to be called APP-1.

About me


My name is Steven Degutis, and I've been writing software professionally for a decade. During that time, I've written many apps and websites, quite a few technical articles, and kept up-to-date with the rapidly evolving software industry.

If you have software needs for web, mobile, or desktop, and are looking for a seasoned software professional, please reach out to me at to set up a phone call.

Work Experience

  • Self-employed – present
  • Clean Coders – 5 years
  • 8th Light – 2 years
  • Big Nerd Ranch – 1 year
  • Self-employed - 1 year


  • Web: full-stack
  • iOS (UIKit)
  • macOS (Cocoa)
  • AWS / EC2 / ELB


  • JavaScript
  • HTML5 / CSS
  • Swift
  • Objective-C
  • Clojure


  • Node.js
  • Express.js
  • React
  • Vue.js
  • Electron

Technical articles

Over the past decade, I've written a total of 172 technical articles on various programming languages, frameworks, best practices, and my own projects, as I kept up-to-date and active in the software industry.

Subscribe via RSS / Atom.



Here are some of the projects I'm most proud of. They were created using a variety of technologies, running on several different platforms and OSes. They're all finished products, and many of them are open source.

Website - Online Video Store

I wrote this web store for Robert "Uncle Bob" Martin, using Clojure for the back-end, and JavaScript for the front-end. Over the course of 5 years, I took the site from a simple three-page website to a full enterprise-ready business solution, with nearly 100% test coverage.

  • Clojure
  • Datomic
  • jQuery / D3.js
  • JavaScript
  • ClojureScript


macOS app - Dock Utility

I made Docks in 2009 for users who wanted to swap out icons in their Dock with a single click. Its unique functionality and design aesthetic attracted the attention of Apple, Engadget, MacWorld, and led to an acquisition of my start-up by Big Nerd Ranch.

  • Staff Pick
  • MacWorld 4/5 Rating
  • MacWorld Gem of the Year
  • Featured on


macOS app - Clojure IDE

Source Code

While working on, a website written completely in Clojure, I increased my productivity by building a custom IDE for macOS designed specifically for Clojure projects.

  • Objective-C
  • Clojure
  • C / C++
  • Cocoa
  • Themeable


macOS app - Hackable Automation

Source Code

This began as an experiment to see how many languages I could use to script a custom macOS window manager using our custom TCP protocol. Eventually it had bindings for Clojure, Ruby, Python, Go, JavaScript, CoffeeScript, Node.js, Chicken Sceme, and Racket, as well as other community additions.

  • TCP / Unix sockets
  • Custom protocol
  • Highly Scriptable
  • 10+ language bindings
  • Open source community

Bubble Maker

iOS app - Bubble simulator

This toy was made in a weekend to entertain my 1 year old daughter. It lets you create bubbles with your fingers, which then simulate physics by bumping into each other and falling.

  • SpirteKit
  • Custom art
  • Physics simulation
  • iOS
  • tvOS

Quick List

iOS app - Todo list app

When I couldn't find an app in the App Store that let me make very simple lists extremely quickly, I made one myself. I use it almost every day to organize and track my activities.

  • In-app purchases
  • Custom UI / UX
  • Social media
  • App Store artwork
  • Spring animations

Website - Personal Portfolio

Source Code

This very site itself was written from scratch in about a day. It uses best practices for modern responsive web design, and a custom build phase to compile the sources into a single HTML file.

  • Node.js
  • Pug / Jade
  • LessCSS
  • HTML5
  • WebSockets


Java app - Game

Source Code

The game 2048 (created by Gabriele Cirulli) is so fun that my kids wanted their own copy. So I wrote this version in Java 8, using JavaFx for attractive graphics and silky smooth animations.

  • Java 8
  • JavaFx
  • Modular code
  • Customizable
  • Animations


macOS app - Window Manager

Source Code

I created this app to increase my productivity by letting me move windows around in macOS using keyboard shortcuts. It grew into a community-driven highly extensible app, using Lua for its plugin system.

  • Objective-C
  • Embedded Lua
  • Plugin system
  • Fully documented
  • 5,000 GitHub stars

Website - Social Network

Implementing this elite social network gave me experience integrating both Apple Pay and credit card payments (via seamlessly into web apps, for a frictionless and pain-free payment experience.

  • Clojure
  • Elastic Beanstalk
  • PostgreSQL
  • Apple Pay


Website - Live Chatroom

Source Code

This isn't just any chatroom. In this web app, you can see what everyone is typing while they type it. I made this in order to scratch my itch for making real-time apps and games, and learned how to use WebSockets in the process.

  • JavaScript
  • WebSockets
  • Node.js
  • Vue.js
  • CSS


macOS app - Music Player

Source Code

As iTunes went through many user interface changes, I wanted an app that was consistent, intuitive, and easy to use. So I created Bahamut, a minimal music player for macOS with a custom user interface.

  • Objective-C
  • Custom UI
  • Cocoa
  • Core Data
  • AVFoundation


macOS app - Chat (IRC) Client

Source Code

This was written in 2009, before the time of Slack, when IRC was the main way for programmers to get short-term assistance from each other. Its purpose was to be a beautiful app with an emphasis on simplicity and usability over technical power.

  • Async networking
  • Core Animation
  • Core Text
  • IRC Protocol
  • UI Design


macOS app - Window Manager

Source Code

This is an app I actually use every single day. It lets you move windows with global keyboard shortcuts. Since it uses Vim-like key bindings, it should feel pretty natural to any programmer. There's no configuration needed; it Just Works™.

  • Minimalist UI
  • Simple UI
  • Vim-like Hotkeys
  • Global Hotkeys
  • Zero-configuration


macOS app - Lua window manager

Source Code

As an evolution of Phoenix, Hydra was my first attempt at embedding a full Lua virtual machine into an Objective-C app, to make a lightweight and efficient window manager that focused on speed, low memory usage, low CPU usage, and overall being gentle on laptop batteries.

  • Embedded Lua
  • Generated docs
  • Lightweight
  • Memory efficient
  • CPU efficient


macOS app - JavaScript window manager

Source Code

As an evolution of Zephyros, Phoenix was my attempt to use Cocoa's native JavaScript bindings to make a more lightweight and efficient window manager, that focused on speed, low memory usage, low CPU usage, and overall being gentle on laptop batteries.

  • JavaScriptCore
  • JavaScript API
  • Lightweight
  • Memory efficient
  • CPU efficient

Smaller projects

These may be tiny, but they're interesting technical feats.

Lua4Swift Swift framework for embedding Lua with a native Swift API.
choose Command line fuzzy-matching tool for macOS that uses a GUI
music Command line music daemon for macOS that only speaks JSON
hecto Command line text editor with an embedded Lua plugin system
ZephSharp Window manager for Windows using Clojure for scripting
management Minimalist EC2 configuration & deployment tool in Ruby.
go.assert Assertion helper package for writing tests in Go.
go.shattr Go library for printing shell-attributed strings to stdout.
OCDSpec2 Objective-C based testing framework with Xcode integration.