Blog posts and open-source work



  • Systems software engineer

Folkert is an expert in systems programming. He has made major contributions to the creation of the (soon-to-be) friendly, fast, functional language called Roc - in fact, he has so far written about half of the code; He co-teaches (and co-creates) the university course Rust 101; And he is working on the Rust implementation of the Network Time Protocol, ntpd-rs.

Difficult problems don´t rattle him. In fact, we can rely on Folkert to face them head-on and produce solid implementations in remarkably little time.

In his spare time, Folkert often continues to work on languages (natural or other) and he likes to cook or spend time in the garden.

In February of 2024, I was invited by Matthias Endler of Corrode to join him on his podcast Rust in Production. We discussed how Tweede golf uses Rust in production, to ensure the safety and security of critical infrastructure software.
Asynchronous programming is pretty weird. While it is straightforward enough to understand in principle (write code that looks synchronous, but may be run concurrently yada yada yada), it is not so obvious how and when async functions actually perform work. This blog aims to shed light on how that works in Rust.
At the GOSIM Conference in Shanghai, last September, I had the opportunity to talk about ntpd-rs, our project implementing the Network Time Protocol.

Open-source work

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ntpd-rs is an open-source implementation of the Network Time Protocol completely written in Rust, with a focus on exposing a minimal attack surface. This video explains how ntpd-rs brings NTP into the modern era.

The project was initially funded by ISRG's Prossimo, as part of their mission to achieve memory safety for the Internet's most critical infrastructure. The NTP initiative page on Prossimo's website tells the story.

ntpd-rs is part of Project Pendulum. In July of 2023 the Sovereign Tech Fund invested in Pendulum, securing development and maintenance in 2023, and maintenance and adoption work in 2024.



Rust 101

Rust 101 is a university course for computer science students, introducing the Rust Programming Language, and is available for anyone who wants to teach Rust.

Have a look at our blog post introducing the course.


Folkert works on Roc and is one of its main contributors. Roc's goal is to be a fast, friendly, functional language.