typeshed

About

Typeshed contains external type annotations for the Python standard library and Python builtins, as well as third party packages as contributed by people external to those projects.

This data can e.g. be used for static analysis, type checking or type inference.

For information on how to use typeshed, read below. Information for contributors can be found in CONTRIBUTING.md. Please read it before submitting pull requests; do not report issues with annotations to the project the stubs are for, but instead report them here to typeshed.

Further documentation on stub files, typeshed, and Python's typing system in general, can also be found at https://typing.readthedocs.io/en/latest/.

Typeshed fully supports Python versions 3.8 and up. Support for Python 3.7 is limited: see python#10113 for details.

Using

If you're just using a type checker (mypy, pyright, pytype, PyCharm, ...), as opposed to developing it, you don't need to interact with the typeshed repo at all: a copy of standard library part of typeshed is bundled with type checkers. And type stubs for third party packages and modules you are using can be installed from PyPI. For example, if you are using six and requests, you can install the type stubs using

$ pip install types-six types-requests

These PyPI packages follow PEP 561 and are automatically released (multiple times a day, when needed) by typeshed internal machinery.

Type checkers should be able to use these stub packages when installed. For more details, see the documentation for your type checker.

Package versioning for third-party stubs

Version numbers of third-party stub packages consist of at least four parts. All parts of the stub version, except for the last part, correspond to the version of the runtime package being stubbed. For example, if the types-foo package has version 1.2.0.7, this guarantees that the types-foo package contains stubs targeted against foo==1.2.* and tested against the latest version of foo matching that specifier. In this example, the final element of the version (7) indicates that this is the eighth revision of the stubs for foo==1.2.*. If an update to the stubs were pushed (but the stubs were still aiming to provide annotations for foo==1.2.*), then the version of types-foo would increment to 1.2.0.8.

At typeshed, we try to keep breaking changes to a minimum. However, due to the nature of stubs, any version bump can introduce changes that might make your code fail to type check.

There are several strategies available for specifying the version of a stubs package you're using, each with its own tradeoffs:

1. Use the same bounds that you use for the package being stubbed. For example, if you use requests>=2.30.0,<2.32, you can use types-requests>=2.30.0,<2.32. This ensures that the stubs are compatible with the package you are using, but it carries a small risk of breaking type checking due to changes in the stubs.

   Another risk of this strategy is that stubs often lag behind the package being stubbed. You might want to force the package being stubbed to a certain minimum version because it fixes a critical bug, but if correspondingly updated stubs have not been released, your type checking results may not be fully accurate.

2. Pin the stubs to a known good version and update the pin from time to time (either manually, or using a tool such as dependabot or renovate).

   For example, if you use types-requests==2.31.0.1, you can have confidence that upgrading dependencies will not break type checking. However, you will miss out on improvements in the stubs that could potentially improve type checking until you update the pin. This strategy also has the risk that the stubs you are using might become incompatible with the package being stubbed.

3. Don't pin the stubs. This is the option that demands the least work from you when it comes to updating version pins, and has the advantage that you will automatically benefit from improved stubs whenever a new version of the stubs package is released. However, it carries the risk that the stubs become incompatible with the package being stubbed.

   For example, if a new major version of the package is released, there's a chance the stubs might be updated to reflect the new version of the runtime package before you update the package being stubbed.

You can also switch between the different strategies as needed. For example, you could default to strategy (1), but fall back to strategy (2) when a problem arises that can't easily be fixed.

The _typeshed package

typeshed includes a package _typeshed as part of the standard library. This package and its submodules contains utility types, but is not available at runtime. For more information about how to use this package, see the stdlib/_typeshed directory.

Discussion

If you've run into behavior in the type checker that suggests the type stubs for a given library are incorrect or incomplete, we want to hear from you!

Our main forum for discussion is the project's GitHub issue tracker. This is the right place to start a discussion of any of the above or most any other topic concerning the project.

If you have general questions about typing with Python, or you need a review of your type annotations or stubs outside of typeshed, head over to our discussion forum. For less formal discussion, try the typing chat room on gitter.im. Some typeshed maintainers are almost always present; feel free to find us there and we're happy to chat. Substantive technical discussion will be directed to the issue tracker.