Release date: May 30, 2018

This is a beta preview of Python 3.7

Python 3.7 is still in development. This release, 3.7.0b5, is now the final planned beta release preview. Originally, 3.7.0b4 was intended to be the final beta but, due to some unexpected compatibility issues discovered during beta testing of third-party packages, we decided to revert some changes in how Python's 3.7 Abstract Syntax Tree parser deals with docstrings; 3.7.0b5 now behaves like 3.6.x and previous releases (refer to the 3.7.0b5 changelog for more information). If your code makes use of the ast module, you are strongly encouraged to test (or retest) that code with 3.7.0b5, especially if you previously made changes to work with earlier preview versions of 3.7.0.

Among the major new features in Python 3.7 are:

• PEP 538, Coercing the legacy C locale to a UTF-8 based locale
• PEP 539, A New C-API for Thread-Local Storage in CPython
• PEP 540, UTF-8 mode
• PEP 552, Deterministic pyc
• PEP 553, Built-in breakpoint()
• PEP 557, Data Classes
• PEP 560, Core support for typing module and generic types
• PEP 562, Module __getattr__ and __dir__
• PEP 563, Postponed Evaluation of Annotations
• PEP 564, Time functions with nanosecond resolution
• PEP 565, Show DeprecationWarning in __main__
• PEP 567, Context Variables

Please see What’s New In Python 3.7 for more information. Additional documentation for these features and other changes may be included prior to the release candidate.

Beta release previews are intended to give the wider community the opportunity to test new features and bug fixes and to prepare their projects to support the new feature release. We strongly encourage maintainers of third-party Python projects to test with 3.7 during the beta phase and report issues found to the Python bug tracker as soon as possible. While the release is planned to be feature complete entering the beta phase, it is possible that features may be modified or, in rare cases, deleted up until the start of the release candidate phase. Our goal is have no ABI changes after beta 3 and no code changes after 3.7.0rc1, the release candidate. To achieve that, it is extremely important to get as much exposure for 3.7 as possible during the beta phase. Please keep in mind that this is a preview release and its use is not recommended for production environments.

The next preview of Python 3.7 will be the 3.7.0 release candidate, now scheduled for 2018-06-11. The official release of 3.7.0 is now planned for 2018-06-27.

Full Changelog