Johannes Wachs
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johanneswachs.bsky.social
Johannes Wachs
@johanneswachs.bsky.social
Researching social computing, crowds, and networks at Corvinus University of Budapest and HUN-REN CERS.

More at: https://johanneswachs.com/

Besides the adoption results, we find newer devs take up AI fastest. We see no gender gap. In fixed-effects models, higher user AI share predicts more commits, and the use of novel code libraries and library pairs. AI extends capabilities and supports exploration.
June 11, 2025 at 8:23 PM
First we built an AI-code detector & gathered data to train it. Human code came from 2018 Python functions & HumanEval 21/23. To create AI-written code examples we had one LLM describe each human example in English then a 2nd LLM coded that description.
June 11, 2025 at 8:23 PM
How much code now comes from AI? With @simonedaniotti.bsky.social, @xfeng.bsky.social & Frank Neffke we estimate that by end-2024 30% of Python functions pushed by US devs on GitHub are AI-generated. Adoption is rapid but diffusion lags globally. How did we do it? arxiv.org/abs/2506.08945
June 11, 2025 at 8:23 PM
The published version of that preprint has a slightly longer descriptive time series in the discussion, see below. We can't extend the counterfactual (comparing SO vs Russian and Chinese platforms) because other LLMs came out.

academic.oup.com/pnasnexus/ar...
February 14, 2025 at 8:36 PM
We also find that most novel library imports and combinations are made by less-experienced users, suggesting how important new blood is for long-run ecosystem health.

Feedback warmly welcome!
November 25, 2024 at 12:20 PM
[Mirrors results on over 200 years of novelties in US patents by Youn et al: royalsocietypublishing.org/doi/full/10.... ].

Two implications for maintenance:
- single libraries will be widely used as ecosystems grow (see plot)
- the many co-used libraries need to stay compatible with each other
November 25, 2024 at 12:20 PM
New preprint on innovation in OSS /w Gabor Meszaros: arxiv.org/abs/2411.14894

We extract library import statements from Stack Overflow posts in 12 languages. These elementary building blocks of code appear at a slower rate as ecosystems grow. But novel combos of libraries grow linearly.
November 25, 2024 at 12:20 PM
Our paper on the effect of ChatGPT on activity on @stackoverflow.com.web.brid.gy is out: academic.oup.com/pnasnexus/ar...

@maria-drc.bsky.social, Nadzeya Laurentsyeva & I find a 25% decrease in activity on SO within 6 months of #ChatGPT 's release vs counterfactuals.

Why does it matter?
November 15, 2024 at 9:28 AM