Brainstorms on Artur Rios Lab

Netbank: A Banking System to Learn From

Thu, 22 Oct 2026 12:30:00 +0000

A complete banking system, built for learning purposes.

Technology

.NET on the back end
Flutter on the front end
Heimdall for authentication and authorization
PostgreSQL database

Platforms

Android
Linux
Windows
Web

What a complete bank covers

“Complete” is the part of the idea that needs a boundary. A real bank is hundreds of systems, so this is a suggestion of what Netbank should cover, chosen because each part teaches something a CRUD app does not. It moves no real money and connects to no real bank: every institution outside Netbank is simulated.

Merlin: A Reading Tracker

Thu, 22 Oct 2026 12:00:00 +0000

Merlin is an app to keep your readings.

Features

Search books from a public database
Track the books you are reading now, and read on the past
Write reviews on books

Platforms

Android
Web

Technology stack

One choice is already made: the app is built with Flutter, which builds the Android app and the web app from one Dart code base. How Flutter works, and what it is good and bad at, is covered in What Is Flutter?. What is left to decide is everything around it: where the books come from, where the readings and reviews are stored, and how the two platforms see the same library.

Craft: A Programming Language

Wed, 21 Oct 2026 17:00:00 +0000

A modern programming language that supports the most used paradigms, and has all the features you need to write elegant solutions.

Features

Multiplatform
Syntax inspired by C#
Proof, parallelism and speed inspired by Bend

Roadmap

Develop a minimal version
Develop and test more features on top of the minimal version
Once we have a first stable version, start to develop simple programs in it
Develop more features, as we test and identify requirements
Build more complex programs and develop the language as we go
After having a stable programming language, with complex projects written on it, create a compiler written in Craft itself
Build an Operating System using the language

Technology stack

A language is two things: the design people write in, and the compiler and runtime that make it run. The stack is mostly the second, but three design choices shape it so much that they come first: how parallelism works, how memory is managed, and what “proof” means. The background on how a compiler is structured is in Compilers, and the way C# itself runs is in How C# Runs.

Anvil OS: An Operating System From Scratch

Wed, 21 Oct 2026 15:00:00 +0000

An open source operating system built from scratch.

Overview

The idea is to build a fully functional operating system, to learn about how an operating system works, and from the simpler version of a kernel, improve it until something really usable.

Roadmap

Start with the simpler version of a kernel
Build functionalities on top of the kernel
Improve as we test

Technology stack

An operating system has almost no stack in the usual sense: there is no runtime, no standard library and no framework beneath it, because it is the thing those normally run on. The choices that matter are the language, the processor architecture, how the kernel gets loaded, and the tools for running and debugging a kernel that cannot print an error when it crashes. The background for all of it is in Operating Systems and Processors.

Thoth: An IDE That Grows With You

Wed, 21 Oct 2026 12:00:00 +0000

An IDE that adapts to your exact needs, nothing more, nothing less.

Features

Starts like a simple and lightweight code editor and the user can activate modules to add functionalities to fill their needs. For example a .NET module, an Angular module etc
Experience must be similar to Visual Studio Code on Linux and Windows and similar to LunarVim on terminal
Do not support extensions, the idea is to use the modules to extend the application on-demand

Platforms

Linux
Windows

First release modules

.NET
Angular
React
Flutter
Python
Rust
HTML/CSS
JavaScript/TypeScript
Java

Technology stack

The feature that shapes the stack most is the second one: the same IDE in a window and in a terminal. If the window and the terminal are two programs, every feature is built twice. So the design starts from one core that owns everything an editor does, such as buffers, cursors, syntax trees, language servers, commands, keymaps and modules, and two thin front ends that only draw what the core describes and send it the user’s input. The core and the front ends talk only through typed messages: input events go in, view updates come out. Neither side calls into the other, so a front end can be replaced, and the core could later run in a separate process, for example on a remote machine over SSH.

Mosaic: A Second Brain App

Wed, 21 Oct 2026 09:00:00 +0000

An app that wants to be your second brain.

Features

Create and organize notes in Markdown
Calendar
To do list
Kanban board
Pomodoro sessions
Mermaid diagrams
Draw diagrams

Inspiration

This app wants to combine features from these apps:

Platforms

Android
Linux
Web
Windows

Technology stack

Two of the features decide most of the stack before anything else is weighed. Excalidraw is published as a React component, and Mermaid is a JavaScript library. Any stack that does not run JavaScript in a web view has to embed one to get them, so the cheapest path is to make the whole app a web app and wrap it for each platform. The suggestion below follows that path.