Welcome to fastcore

Python supercharged for the fastai library


fastcore is on PyPI so you can just run:

pip install fastcore

For an editable install, use the following:

git clone
cd fastcore
pip install -e ".[dev]"


To run the tests in parallel, launch:



make test


After you clone this repository, please run nbdev_install_git_hooks in your terminal. This sets up git hooks, which clean up the notebooks to remove the extraneous stuff stored in the notebooks (e.g. which cells you ran) which causes unnecessary merge conflicts.

Before submitting a PR, check that the local library and notebooks match. The script nbdev_diff_nbs can let you know if there is a difference between the local library and the notebooks.

  • If you made a change to the notebooks in one of the exported cells, you can export it to the library with nbdev_build_lib or make fastcore.
  • If you made a change to the library, you can export it back to the notebooks with nbdev_update_lib.

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