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python Python Insider · · 3.15.0

Python 3.15.0 Beta 4 Released with Numerous Fixes and Features

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feature patch announcement

Python 3.15.0 beta 4 is now available, marking the final beta release before the release candidate phase. This version includes approximately 298 bug fixes, build improvements, and documentation changes, along with major new features like explicit lazy imports and a new frozendict built-in type. Developers are encouraged to test their projects with this preview to prepare for the stable release, though it is not recommended for production use.

  • →PEP 810: Explicit lazy imports for faster startup
  • →PEP 814: Addition of frozendict built-in type
  • →PEP 661: Introduction of sentinel built-in type
  • →PEP 799: Dedicated profiling package and Tachyon profiler
  • →PEP 799: Unpacking in comprehensions
Features (5) ›
  • PEP 810: Explicit lazy imports for faster startup

    This release introduces PEP 810, enabling explicit lazy imports to improve Python's startup times.

  • PEP 814: Addition of frozendict built-in type

    Python 3.15.0 beta 4 includes PEP 814, which adds a new immutable frozendict built-in type.

  • PEP 661: Introduction of sentinel built-in type

    The release brings PEP 661, adding a sentinel built-in type to the language.

  • PEP 799: Dedicated profiling package and Tachyon profiler

    A new dedicated profiling package, including the Tachyon high-frequency statistical sampling profiler, is introduced under PEP 799.

  • PEP 799: Unpacking in comprehensions

    Python 3.15.0 beta 4 supports unpacking in comprehensions as defined by PEP 799.

Enhancements (1) ›
  • Frame pointers enabled by default for improved observability

    PEP 831 ensures that frame pointers are enabled by default in this release, enhancing system-level observability.

Read the original announcement →

https://blog.python.org/2026/07/python-3150-beta-4/

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