Presentations and abstracts for PyConFr 2025

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During PyConFr 2025 , I’d like to present and co-present things about 3 subjects:

Sprint on py-edu-fr

Py-edu-fr ( https://python-cnrs.netlify.app/edu ) est un réseau de personnes travaillant avec Python, notamment dans l’enseignement supérieur et la recherche. Nous nous proposons de produire et organiser collectivement avec la communauté Python des formations Python dans des pays francophones.

Nous proposons un sprint durant la PyConFr pour travailler à différents aspets du project, en particulier la préparation de deux formations en présentiel “Python initiation” ( https://python-cnrs.netlify.app/edu/init/ ) et “Python avancé pour la science” ( https://python-cnrs.netlify.app/edu/science/ ).

Proposition about HPy

Title: Universal Python extensions: performance, compatibility, sustainability, and less CO₂

Python’s long-term relevance for numerical computing faces a long-term threat, not from external competition alone, but from fundamental architectural decisions that prevent the entire ecosystem from achieving better performance. While PyPy and GraalPy can make pure Python code 4x faster than CPython, they face an existential crisis: the moment you import NumPy or any package with C extensions, that performance advantage disappears completely.

This isn’t just a technical curiosity. It’s putting alternative Python implementations in genuine danger of end-of-life status.

The hard truth about Python’s performance future

The compatibility trap: Python’s C extension system creates an insurmountable barrier between implementations. Popular packages like NumPy, Pandas, and scikit-learn are locked into CPython-specific APIs, making faster interpreters effectively unusable for real-world numerical work. Worse, the current C API also constrains CPython itself, preventing future performance improvements that would break existing extensions.

HPy: promise and reality: The HPy project aimed to solve this with a universal C API, showing impressive preliminary results with extensions that work across CPython, PyPy, and GraalPy. However, the project has stalled without sufficient corporate and community support, a critical opportunity slipping away.

The limited API alternative: CPython’s limited C API offers another path, but with significant constraints and unclear long-term viability for the ecosystem’s needs.

What this talk proposes

Rather than accepting this situation, we need coordinated community action. This talk argues for:

  • Community recognition: The Python community must acknowledge these performance limitations as a serious long-term challenge, not just a nice-to-have improvement.

  • Official support: A PEP process to formalize the need for universal C API/ABI solutions friendly with JIT Python compilers, with a dedicated working group to study possible solutions and coordinate actions across different ecosystem actors.

Why we need to act now

The stakes extend far beyond technical performance. Enabling more efficient Python interpreters would have two transformative effects:

  • More Python: Performance-sensitive code could be written in pure Python with object-oriented patterns and small objects, rather than requiring native extensions, simplifying development and deployment.

  • Environmental impact: Given Python’s massive global usage, significant performance improvements would translate to measurable CO2 emission reductions across millions of applications worldwide.

Without community mobilization, we risk losing both alternative Python implementations and Python’s competitive position in performance-critical domains. The technical foundations exist but need coordinated effort to become reality.

Target Audience

This talk is for Python developers who care about the ecosystem’s long-term health. Whether you’re a package maintainer or concerned user, you’ll understand the stakes and learn how to contribute to solutions.

Come prepared to discuss hard truths about Python’s future and leave with concrete actions for community engagement.