Building the deployment tool I wish I had
Deptool is a new declarative configuration deployment tool that I built for myself. In this post I describe the design, and I explain what problems it solves.
Ruud van Asseldonk
Latest posts
AI is making me paranoid about contributions
AI has gotten to a point where I can no longer tell to what extent I’m dealing with a human online, and it’s taking a toll on my mental health.
Adding unpack syntax to RCL
In this post I explore the design space of adding unpack syntax to RCL. Due to RCL having sets, there are interesting trade-offs here.
Abstraction, not syntax
Alternative configuration formats solve superficial problems. Configuration languages solve the deeper problem: the need for abstraction.
The story of Musium
One of my longest running side projects is Musium, the music player I built for myself. In this post I explain why I built it, and I highlight some interesting parts of the process.
Automating configuration updates with rcl patch
Configuration formats that humans can read and maintain, are hard for scripts to edit safely. With the new patch feature, RCL now has a principled way to enable safe, automated edits.
Rotating my PGP key
I revoked my former PGP/GPG key on July 29, 2025.
A float walks into a gradual type system
In this post I explore the design space of adding floats to RCL, a gradually typed configuration language. With floats in place, RCL is finally a true json superset.
LLM text makes human interactions less fun
Building connections with other people is what makes life fun. When humans communicate through LLM-written text, we lose that.
A type system for RCL: Implementing a typechecker in Rust
I am adding a type system to RCL, my configuration language. In part 4, we look at how the typechecker is implemented in Rust, and at how it is able to generate good error messages.
A type system for RCL: Related work
I am adding a type system to RCL, my configuration language. The type system is based on ideas from other systems. In part 3, I highlight prior work, and I contrast RCL’s type system with that of other configuration languages.
A type system for RCL: The type system
I am adding a type system to RCL, my configuration language. In part 2, I explain how the type system works. It is based on lattices and features a generalized subtype check.
A type system for RCL: Introduction
I am adding a type system to RCL, my configuration language. In part 1, I explain what I want from the type system.
AI alignment starter pack
In this post I share resources for learning more about AI alignment, and why misalignment is a risk that I take seriously.
A reasonable configuration language
I was fed up with the poor opportunities for abstraction in configuration formats. The many configuration languages that exist already were not invented here, so I wrote my own, at first just for fun. But then it became useful.