Jonathan Brachthäuser

Researcher in computer science,
all things effects, author of the Effekt language (
Professor at Uni Tübingen.

[Jonathan Brachthäuser @__protected]

I am more than proud of my PhD students, colleagues and collaborators!

Together we managed to have 5 papers at this year's OOPSLA'25 (R1 and R2) and 1 at the colocated ICFP'25.

🥳🎉

The papers cover a wide range of PL and compiler topics 🧵

[Jonathan Brachthäuser @__protected]

@ShriramKMurthi As far as I know Meta didn't publish anything about it, yet.

[Jonathan Brachthäuser @__protected]

@ShriramKMurthi This is something we also hoped to see from our very detailed, flow-based error messages (https://t.co/gPKLtLXwIB), which have been implemented in meta's Hack (for example, https://t.co/Imo9wOsARc) as "extended reasons".

[Jonathan Brachthäuser @__protected]

@flixlang You mean: single file + a readme, right? ;)

[Leonardo de Moura @Leonard41111588]

Claude code, with no special training for theorem proving, converted zlib to Lean and proved the roundtrip correct. Minimal human guidance.

Decompress after compress always returns the original data.
https://t.co/fvF7BOYBQ8

[Satnam Singh @satnam6502]

goto makes a comeback. The goto rule might be simple but Hoare pointed out its application is complicated for human brains, but LLM-code generators don't care.

[flix @flixlang]

1/2 Excited about Flix or effects? Help us out by solving some programming challenges in our interactive study. Takes 10-15min. Link👇

[Jonathan Brachthäuser @__protected]

It has been an honor and pleasure doing my Postdoc with Martin!

[EPFL @EPFL_en]

Martin Odersky, EPFL professor and head of the Programming Methods Laboratory, developed the programming language Scala, which is used by thousands of companies worldwide. In 2025, he was awarded the Programming Languages Achievement Award.

https://t.co/H0eTW9o5Ee

[EPFL @EPFL_en]

Martin Odersky, EPFL professor and head of the Programming Methods Laboratory, developed the programming language Scala, which is used by thousands of companies worldwide. In 2025, he was awarded the Programming Languages Achievement Award.

https://t.co/H0eTW9o5Ee

[Jules Jacobs @JulesJacobs5]

The program for the Oregon Programming Languages Summer School 2026 looks exciting: https://t.co/KYkbLN8WqG

Come or send your students!

[Jonathan Brachthäuser @__protected]

Anybody at POPL (@poplconf) this week?

If so, please say hi to our student Alexander Phi Goetz, who is presenting his work on type system design for delimited control operators at the SRC.

It is his first conference and I am sure he would be happy if you say hi :)

[Jonathan Brachthäuser @__protected]

@aramh Maybe this article by my friend David could interest you (if you didn't know it already)

https://t.co/OQYvTZ02MZ

[Yaron (Ron) Minsky @yminsky]

We're looking to hire an experienced editor with a taste for fancy type-systems to work on education for OxCaml!

Please share with anyone you think might be a good fit for this role. (And...retweets wouldn't hurt.)

[Jonathan Brachthäuser @__protected]

@aramh We wrote a grant proposal about this very point ~4 years ago. It was rejected.

Reviewers said: who cares about this? By now we can motivate it way more practically, but I am still sad why mathematical elegance and curiosity isn't enough motivation.

[POPL 2026 @poplconf]

POPL'26 registration has opened!

We will have an amazing program -- join us!

https://t.co/64Vhg42zm5

[POPL 2026 @poplconf]

The ACM SIGPLAN Workshop on Partial Evaluation and Program Manipulation (PEPM'26), co-located with POPL'26 in Rennes, France is calling for papers!

Submission deadline: Friday 24 Oct 2025

https://t.co/HxXVHn3ptC

[Jonathan Brachthäuser @__protected]

I am very happy that you enjoy our work :)

Let me know if you have any questions

[Felipe O. Carvalho @_Felipe]

@geofflangdale This recent OOPSLA paper shows a very elegant way of dealing with overloads and rendering nice error messages when there’s more than one possible call. The online demo shows you how it looks.

[Jonathan Brachthäuser @__protected]

@AppleSupport Here is the command I use to delete the plist files in order to allow reconnecting (after reboot):

sudo rm /Library/Preferences/com.apple.windowserver.displays.plist sudo rm ~/Library/Preferences/ByHost/com.apple.windowserver*.plist

This workaround is not viable in practice.

[Jonathan Brachthäuser @__protected]

@AppleSupport M1 MacBook Pro (macOS 15.7.1):

Using "Mirror app window" via HDMI then "Stop mirroring window" permanently breaks external display detection. Projector shows black screen, display disappears from settings.

Fix: delete display plist files via Terminal & reboot.

[Jonathan Brachthäuser @__protected]

@AppleSupport I can reproduce this bug reliably. Similar issues showed up multiple times now on different projectors which makes it impossible to reconnect. This is a major blocker for me since I need to mirror my screen in my lectures.

[Jonathan Brachthäuser @__protected]

@grashalm_ Thanks Christian :)

[Jonathan Brachthäuser @__protected]

That's it from us for this ICFP / SPLASH 🫳🎤

If you missed our talks, you can read about them here https://t.co/EZ3NsDYGzR

and I'm sure the recordings will pop up on the SIGPLAN YouTube channel at some point.

[Jonathan Brachthäuser @__protected]

I am more than proud of my PhD students, colleagues and collaborators!

Together we managed to have 5 papers at this year's OOPSLA'25 (R1 and R2) and 1 at the colocated ICFP'25.

🥳🎉

The papers cover a wide range of PL and compiler topics 🧵