A recent proposal to incorporate Rust into the CPython codebase is gaining attention within the Python developer community. The initiative, led by two CPython core developers, outlines a phased approach to leverage Rust’s capabilities to enhance Python’s performance and safety.
The proposal suggests initially introducing optional extension modules implemented in Rust with a gradual transition to making it a required dependency for CPython. The primary benefits outlined include eliminating memory safety bugs, improving thread safety, and offering zero-cost abstractions, all of which are of significant importance given Python’s extensive use in various applications.
Implementation of this proposal would involve using ‘bindgen’ for creating C API bindings and introducing a new ‘cpython-sys’ crate to manage the Rust-C integration. A tentative timeline is proposed: issuing warnings about the upcoming changes in Python 3.15, making it a conditional requirement by 3.16, and fully integrating Rust as a necessary component by 3.17.
However, the initiative isn’t without challenges. One concern is that while all 20 officially supported CPython platforms have some level of Rust support, 11 are categorized as Tier 3, and older platforms such as RISC OS and HP PA-RISC lack Rust support entirely. The dependency loop created—where Rust needs Python for its build process—further complicates this transition, mirroring recent changes in Debian APT’s requirements.
The developers recognize potential dependency management issues, bootstrapping challenges, and the need for existing contributors to become familiar with Rust. Nonetheless, they believe that integrating Rust will fundamentally improve CPython’s development trajectory by enhancing its core infrastructure capabilities and safety.

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CPython core developers propose integrating Rust into the Python interpreter through a phased approach spanning Python 3.15 to 3.17. The initiative aims to eliminate memory safety bugs, improve thread safety, and leverage zero-cost abstractions. Implementation would use bindgen for C API bindings and a new cpython-sys crate. Challenges include limited Rust support on 11 Tier 3 platforms, circular dependency issues with Rust's build process requiring Python, and the learning curve for existing contributors.

Integrating Rust into the CPython Codebase