Zac Hatfield-Dodds
Research Scientist at Anthropic
San Francisco, California, United States
Summary
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RockstarZac Hatfield-Dodds is a research scientist and seasoned software engineer based in San Francisco with 11 years of experience improving reliability across core Python ecosystems. He’s an active open-source maintainer and PSF Fellow who blends rigorous QA and test automation with backend development—contributions span CPython, NumPy, pytest, Sphinx, Matplotlib and other high-profile projects. Zac specializes in property-based testing (Hypothesis) and doctest-driven validation, having introduced CI and fuzz-testing practices to projects like Astropy, Black, and NumPy to catch subtle, production-impacting issues. His work also touches data-science ergonomics and imaging (xarray, matplotlib) and developer tooling (flake8-bugbear, argparse/typing improvements), demonstrating attention to both user-facing behavior and developer experience. Colleagues rely on him for clear technical writing and documentation improvements that make complex features accessible and reliably testable.
11 years of coding experience
Stackoverflow
2,753reputation
52kreached
121answers
3questions
python
top-5%
Github Skills (73)
restructuredtext10
python10
testing10
guideline10
triple10
triplet10
automation10
async-await10
linter10
async10
xray10
rs10
implicit-typing10
numpy10
user-guide10
Programming languages (26)
Github contributions (5)
PyCQA/flake8-bugbear
Jan 2020 - Jan 2023
A plugin for Flake8 finding likely bugs and design problems in your program. Contains warnings that don't belong in pyflakes and pycodestyle.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:27 reviews, 12 commits, 15 PRs in 3 years
Contributions summary:Zac primarily contributed to the `flake8-bugbear` plugin, adding new checks and improving existing ones related to Python code quality. They implemented checks for exception handling, specifically addressing redundant exception types and tuple literals in `except` clauses, and also incorporated a check for late-binding loop variables. The user's work also included fixing bugs, such as those related to attribute access within `except` clauses, and adding tests to validate the changes and ensure the plugin's functionality. Furthermore, they added support for new checks and documented the changes.
flakepycodestylepyflakescode-qualitylinter
python-trio/trio
May 2018 - Nov 2022
Trio – a friendly Python library for async concurrency and I/O
Role in this project:Back-end Developer
Back-end DeveloperContributions:123 reviews, 25 commits, 49 PRs in 4 years 6 months
Contributions summary:Zac primarily focused on enhancing the Trio library's core functionality and maintainability. Their contributions include adding type annotations using Mypy, improving static analysis, and refactoring code for better clarity and efficiency. They also addressed specific issues related to concurrency, socket handling, and error management, enhancing the library's robustness. Moreover, the user implemented deterministic scheduling to facilitate reproducibility.
asyncconcurrencypythonasync-awaitnetworking
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