ZuriHac is the biggest Haskell community event in the world: a completely free, three-day grassroots coding festival co-organized by the Zürich Friends of Haskell and the OST Eastern Switzerland University of Applied Science. It is not your standard conference with papers and presentations, but features fantastic keynotes, hands-on tracks, hacking on many of your favourite projects, and of course lots of socializing!
ZuriHac 2025 takes place Saturday 7 June — Monday 9 June as a physical event at the beautiful Rapperswil-Jona campus of OST located right next to lake Zürich. We hope to see you there!
Speakers
“MicroHs - A small Haskell compiler”
MicroHs is a compiler for Haskell2010 + extensions. It compiles to SKI combinators and has a reasonably simple runtime that interprets the combinator graph. The runtime is simple enough to run Haskell programs on, e.g., microcontrollers.
In this talk I will describe some highlights (and lowlights) of implementing MicroHs. And there will also be some live demos.
Lennart Augustsson works at Epic Games and was previously a lecturer at Chalmers University of Technology. He likely holds the world record for the most Haskell compiler implementations.
“Haskell for competitive programming”
Over the past ten years, I have solved over 1700 competitive programming problems in Haskell, just for fun (as well as a few that were not fun). I will give a brief introduction to competitive programming and show off some examples demonstrating the unique benefits of Haskell in this context. We will then have a miniature programming contest, open to all - only Haskell allowed!
Brent Yorgey is an assistant professor at Hendrix College. He is one of the people behind diagrams, which you may have used before. Currently, he is working on a 2D programming game called Swarm.
Zoë Kooyman is the executive director of the Free Software Foundation. She has a deep interest in the visual and digital nature of modern society. She graduated from the University of Amsterdam, where her understanding of copyright was profoundly influenced by the concepts of copyleft and user freedom.
“Category Theory Track”
We introduce category theory from first principles, asking what category theory is and what's so great about it. We introduce the main ideas of categories and functors, and will also touch on topics like natural transformations and the Yoneda lemma if time allows.
Richard Southwell is a mathematician who works as a researcher for PlantingSpace where he applies category theory to knowledge representation. He also makes YouTube videos series such as Category Theory For Beginners and Modern Foundations of Mathemathics.
“Beginner Track”
Andres is a partner at Well-Typed. He has been a active contributor, speaker and organizer in the Haskell community for over 20 years. Currently he hosts the Haskell Unfolder and chairs the Haskell Foundation board.
“The History of Effect Systems”
Tom is a software engineer at Groq and a member of the Haskell Foundation board. He is the designer and maintainer of Opaleye and Bluefin.
“Making Risk Decisions @ Mercury”
Mercury's monolithic Haskell backend is developed by over 200 engineers and contains over 12000 modules. Find out how the risk and compliance team integrates pure functional policies throughout the application without increasing build times or forcing other teams to change the way they work.
Alex is a functional programming enthusiast with 8 years of industry Haskell experience. He'll find a way to apply it anywhere, from turn-based games to real-time ventilator control software. He currently works on building predictable and testable risk control systems at Mercury.
“WASM Track”
Cheng “TerrorJack” Shao is the project lead and main developer of Tweag's Haskell-to-WebAssembly compiler. He also maintains other Haskell projects and makes frequent contributions to GHC.
“Nix Track”
This workshop is aimed at Haskell users who are already familiar with building Haskell projects but may not have experience with Nix. The goal of the workshop is to add Nix to your Haskell toolbelt, helping you streamline your development process in both open-source and industry settings.
In the interest of saving time, we ask that attendees come with Nix pre-installed on their computers. See here for instructions. Note that you can use Nix even if you do not use NixOS. 😉
Malte is a mathematical physicist who writes Haskell at Heilmann Software and in Open Source projects. He is member of the NixOS Haskell team and the GHC steering committee.
Schedule
ZuriHac is primarily a community event and a hackathon, rather than a conference. Aside from the talks and tracks, attendees are encouraged to work together on all sorts of Haskell-related open-source projects and socialize. Trying to attend everything may a bit too much, so our recommendation is just pick to what you find interesting!
Here is a list of projects participants are planning to work on—feel free to add your own!
This schedule is tentative and minor changes may still need to happen as we get closer to the event.
| Start | End | Title | Link | Kind |
|---|---|---|---|---|
| 2025-06-07T09:00:00+02:00 | 2025-06-07T10:00:00+02:00 | Registration Opens | admin | |
| 2025-06-07T10:00:00+02:00 | 2025-06-07T11:00:00+02:00 | Talk by Lennart Augustsson | #speaker-lennart-augustsson | talk |
| 2025-06-07T11:00:00+02:00 | 2025-06-07T12:00:00+02:00 | Opening Presentation & Project Pitches | admin | |
| 2025-06-07T12:00:00+02:00 | 2025-06-07T14:00:00+02:00 | Food Truck | food | |
| 2025-06-07T13:30:00+02:00 | 2025-06-07T15:30:00+02:00 | Beginner Track by Andres Löh | #speaker-andres-loeh | beginner |
| 2025-06-07T14:00:00+02:00 | 2025-06-07T16:00:00+02:00 | WASM Track by Cheng Shao | #speaker-cheng-shao | advanced |
| 2025-06-07T17:00:00+02:00 | 2025-06-07T18:00:00+02:00 | Panel Discussion: Haskell in the Industry | talk | |
| 2025-06-07T18:00:00+02:00 | 2025-06-07T20:30:00+02:00 | BBQ hosted by Jane Street | food | |
| 2025-06-08T10:00:00+02:00 | 2025-06-08T11:00:00+02:00 | Talk by Tom Ellis | #speaker-tom-ellis | talk |
| 2025-06-08T12:00:00+02:00 | 2025-06-08T14:00:00+02:00 | Food Truck | food | |
| 2025-06-08T13:30:00+02:00 | 2025-06-08T15:30:00+02:00 | Beginner Track by Andres Löh | #speaker-andres-loeh | beginner |
| 2025-06-08T13:30:00+02:00 | 2025-06-08T16:30:00+02:00 | Category Track by Richard Southwell | #speaker-richard-southwell | advanced |
| 2025-06-08T17:00:00+02:00 | 2025-06-08T18:00:00+02:00 | Talk by Alex Vieth | #speaker-alex-vieth | talk |
| 2025-06-08T18:00:00+02:00 | 2025-06-08T20:00:00+02:00 | Food Truck | food | |
| 2025-06-09T10:00:00+02:00 | 2025-06-09T11:00:00+02:00 | Talk by Brent Yorgey | #speaker-brent-yorgey | talk |
| 2025-06-09T11:15:00+02:00 | 2025-06-09T12:00:00+02:00 | Talk by Zoë Kooyman | #speaker-zoe-kooyman | talk |
| 2025-06-09T12:00:00+02:00 | 2025-06-09T14:00:00+02:00 | Food Truck | food | |
| 2025-06-09T13:00:00+02:00 | 2025-06-09T15:00:00+02:00 | Nix Track by Malte Ott | #speaker-malte-ott | advanced |
| 2025-06-09T15:30:00+02:00 | 2025-06-09T16:15:00+02:00 | Project presentations | admin | |
| 2025-06-09T16:15:00+02:00 | 2025-06-09T17:00:00+02:00 | Closing | admin |
ZuriHac Prelude
The Haskell Ecosystem Workshop and the Haskell Implementors’ Workshop will take place on the two days just prior to ZuriHac 2025, June 5 & 6 2025. Organised by the Haskell Foundation and the OST Eastern Switzerland University of Applied Sciences in Rapperswil, these events are co-located with the ZuriHac. Registration is on eventbrite.
Haskell Ecosystem Workshop
The Haskell Ecosystem Workshop is for those of you who want to gain a deeper understanding of the Haskell tooling ecosystem, whether to better leverage those tools or to become contributors. Contact Jose Calderon, executive director of the Haskell Foundation, if you have any questions.
Haskell Implementors’ Workshop
The Haskell Implementors’ Workshop (HIW) is a community event for people involved in the design and development of Haskell implementations, tools, libraries, and supporting infrastructure to share their work and to discuss future directions and collaborations with others. Until 2024, the HIW used to be co-located with ICFP (International Conference on Functional Programming). In 2025, it will be co-located with ZuriHac to be accessible to a broader audience. Contact Andreas Herrmann, the HIW program chair, if you have any questions.
Venue
OST
The hackathon takes place at the beautiful Rapperswil-Jona campus of OST (formerly HSR), about 40 minutes outside of Zürich city:
The venue is located right next to the lake, and weather has been superb (25°C, 77℉) during the pre-COVID19 years, so feel free to bring your swimming gear!
Getting There
How to get there by train
We recommend attendees to use public transportation. You can take the S5, S7 or S15 trains to get from the Zürich main station to Rapperswil. These trains run regularly in 30 minute intervals.
What train tickets do I need?
If you stay in Zürich city, the easiest option is to get a 24 hour pass for all zones. It's good for all public transportation around Zürich, up to Rapperswil. A one-way ticket costs 17.20CHF, the 24 hour pass 34.40CHF.
Please note that the 24 hour pass is literally a 24 hour pass and can be used over multiple days: e.g. if you buy one on the first day of the Hackathon at e.g. 9.00 AM, you can still use it to take the train at 8.00 AM the next day. This way, it is possible to buy only two tickets for the three-day conference.
A lightly cheaper alternative to the 24 hour pass is the 9 O'Clock day pass which works more like a regular day pass. However, this requires you to take the train to Rapperswil after 09:00 AM on weekdays, as described on the website.
You can buy tickets from the SBB or ZVV vending machines, which have a button to use them in English rather than German on the home screen. Alternatively, you can use the SBB website, SBB mobile app on Android or iOS.
How to get there by car
There are some paid public parking lots in walking distance from the campus (see here for a map). It can be difficult to find a free parking spot in these lots, and you can expect to pay about CHF 20 per day. We therefore recommend that you come via public transport if possible.
Accomodation
Where to stay
The accommodation situation in and around Rapperswil is, unfortunately like every year, tight. Summer, regardless of the weekend, is a very popular time in the area, with something or the other always going on.
What alternatives are there to Rapperswil?
The nearby city of Zurich has a much larger capacity of hotels and accommodations of varying types. The public transport to Rapperswil is frequent, convenient, and fast. The following stations have direct train connections to Rapperswil every 30 minutes:
- Zurich Hardbrücke
- Zurich Hauptbahnhof
- Zurich Stadelhofen
- Zurich Oerlikon
- Zurich Altstetten
During previous years, attendees have also shared accomodation (e.g. on
Airbnb). In order to get in touch with
fellow attendees, we recommend using the #accomodation channel
in our Discord (which you can join upon registration).
If weather allows for it, camping is also a very affordable and beautiful option for the ultimate grassroots ZuriHac festival fans. Several people have stayed at this campsite since 2017.
Supported by
Community Partners
About
Contact
The main organizers for ZuriHac 2024 are Jasper Van der Jeugt, Farhad Mehta and Alex Drake. Additional key people include Andreas Herrmann, Benjamin Plattner, Bieke Hoefkens, Cazim Hysi, Jeremy Stucki, John Rodewald, Lukas Buchli, Mario Aeberhard, Olivier Lischer, Raphael Das Gupta, Silvan Hegner, and Vaibhav Sagar.
If you have any questions before the event, please reach out to to the organizers. You can also interact with us on our social media accounts: Mastodon, Bluesky, Twitter.
Legal
Each participant will retain ownership of any and all intellectual and industrial property rights to their work created or used during the Hackathon.
ZuriHac uses the Berlin Code of Conduct.