* Align compiler futures and annotations with CPython Handle Barry parsing consistently across AST, type-comment, REPL, and WASM paths. Preserve deferred annotation source and scope metadata, and make _symtable conversion cached and linear-time. Assisted-by: Codex:gpt-5.4 * Fix f-string debug ranges and update Barry/annotate test expectations Compute the debug f-string source range from the raw leading and trailing text instead of the comment-stripped text, so a comment inside a multi-line replacement field no longer shifts the emitted LOAD_CONST location. Restrict the obsolete-operator location shift to `<>` by also requiring a `>` at the reported offset; without it any `ExpectedExpression` that followed a `<` (`2 <;`) was reported one column to the left. Add `CodeFlags::FUTURE_MASK` and use it in builtins, the shell, and the WASM VM instead of repeating the eight-flag union, and collapse the duplicated Barry diagnostic sequences into `BarrySource::diagnostic`. Update the `__annotate__` disassembly snapshot to LOAD_FAST_BORROW and replace the RustPython-only `barry_as_FLUFL` co_flags assertion in extra_tests with the CPython-matching one. Assisted-by: Claude Code:claude-opus-5 * Restore the annotated function in __annotate__ qualnames Signature annotation scopes are compiled in the scope enclosing the annotated function, so the function name has to be folded back into the qualname: `f.__annotate__`, `C.m.__annotate__`, `outer.<locals>.inner.__annotate__`. test_type_annotations test_annotate_qualname covers this. test_pyrepl test_future_barry_as_flufl now passes, so drop its expectedFailure marker. Assisted-by: Claude Code:claude-opus-5 * Pass safepoints in the attached-thread interpreter tests `main_and_subinterpreter_run_sections_overlap` parked its workers on a condvar while attached, and `busy_main_interpreter_does_not_block_subinterpreter` looped over protocol calls that never reach a safepoint. An attached thread that never reaches a safepoint cannot be suspended, so a concurrent process-wide stop-the-world (from the gc test running in parallel) never completes and the already-stopped sibling interpreter stays stopped; the second worker then waits in `wait_while_suspended` until the 30s deadline. Both loops now call `vm.check_signals()` each iteration, and the condvar wait uses `wait_timeout` so the lock is released between safepoints. Reproduced on Linux (4 CPUs): the two tests with `--test-threads=2` failed 2/40 before and 0/40 after; the full `rustpython-vm` lib binary failed 1/30 before and 0/30 after. Assisted-by: Claude Code:claude-opus-5 * Report the obsolete `<>` operator from one place `<>` was located twice: `BarrySource` recorded the token ranges it rewrote to `!=`, and `cpython_parse_diagnostic_override` separately peeked at the bytes around an `ExpectedExpression` location. Both produced "invalid syntax" spanning the whole operator. `prepare_barry_as_flufl_source` now records the operator ranges in the non-Barry case too -- by plain text search, since nothing is rewritten there -- so `BarrySource::invalid_legacy_operator` covers both, and the byte-peeking helper is gone. It also defers to an unclosed bracket earlier in the source, which the diagnostic chain it used to sit in did for it. A `<>` that starts a statement now spans both characters: the parser stops at the `<` rather than one character in, which the byte peek did not handle. Assisted-by: Claude Code:claude-opus-5 * Drop a py object's payload before its class `PyInner` declares `typ` before `payload`, so `drop_in_place` dropped the class first and `PyAtomicRef::drop` left it null. A `PyWeak` payload is still linked into the weakref list of the object it points at until its own `Drop` unlinks it under the stripe lock, which happens after that. `WeakRefList::add` walks the same list looking for a proxy to reuse and reads `node.class()` off every node it passes, so it could dereference the null class of a node on its way out. `PyInner::dealloc` now runs the two destructors in the other order at all three of its exit paths, with a compile-time check that no other field has one. Reproduced by the new test in about 0.1s, as the panic CI hit in the c-api `weakrefobject::tests::new_proxy` run: panicked at crates/vm/src/object/ext.rs:312: unsafe precondition(s) violated: hint::unreachable_unchecked must never be reached Assisted-by: Claude Code:claude-opus-5
RustPython
A Python-3 (CPython >= 3.14.0) Interpreter written in Rust 🐍 😱 🤘.
Usage
Check out our online demo running on WebAssembly.
RustPython requires Rust latest stable version (e.g 1.67.1 at February 7th 2023). If you don't currently have Rust installed on your system you can do so by following the instructions at rustup.rs.
To check the version of Rust you're currently running, use rustc --version. If you wish to update,
rustup update stable will update your Rust installation to the most recent stable release.
To build RustPython locally, first, clone the source code:
git clone https://github.com/RustPython/RustPython
RustPython uses symlinks to manage python libraries in Lib/. If on windows, running the following helps:
git config core.symlinks true
Then you can change into the RustPython directory and run the demo (Note: --release is
needed to prevent stack overflow on Windows):
$ cd RustPython
$ cargo run --release -- -c 'print("Hello, RustPython!")'
Hello, RustPython!
Or use the interactive shell:
$ cargo run --release
Welcome to rustpython
>>>>> 2+2
4
NOTE: For windows users, please set RUSTPYTHONPATH environment variable as Lib path in project directory.
(e.g. When RustPython directory is C:\RustPython, set RUSTPYTHONPATH as C:\RustPython\Lib)
You can also install and run RustPython with the following:
$ cargo install --git https://github.com/RustPython/RustPython rustpython
$ rustpython
Welcome to the magnificent Rust Python interpreter
>>>>>
venv
Because RustPython currently doesn't provide a well-packaged installation, using venv helps to use pip easier.
$ rustpython -m venv <your_env_name>
$ . <your_env_name>/bin/activate
$ python # now `python` is the alias of the RustPython for the new env
PIP
If you'd like to make https requests, you can enable the ssl feature, which
also lets you install the pip package manager. Note that on Windows, you may
need to install OpenSSL, or you can enable the ssl-openssl-vendor feature instead,
which compiles OpenSSL for you but requires a C compiler, perl, and make.
OpenSSL version 3 is expected and tested in CI. Older versions may not work.
Once you've installed rustpython with SSL support, you can install pip by running:
cargo install --git https://github.com/RustPython/RustPython
rustpython --install-pip
You can also install RustPython through the conda package manager, though
this isn't officially supported and may be out of date:
conda install rustpython -c conda-forge
rustpython
SSL provider
For HTTPS requests, ssl-rustls-aws-lc is enabled by default for the RustPython binary. Embedders can use rustpython-stdlib's provider-agnostic ssl-rustls feature and install their own rustls crypto provider, or replace rustls with ssl-openssl if their environment requires OpenSSL.
Note that to use OpenSSL on Windows, you may need to install OpenSSL, or you can enable the ssl-openssl-vendor feature instead,
which compiles OpenSSL for you but requires a C compiler, perl, and make.
OpenSSL version 3 is expected and tested in CI. Older versions may not work.
WASI
You can compile RustPython to a standalone WebAssembly WASI module so it can run anywhere.
Build
cargo build --target wasm32-wasip1 --no-default-features --features freeze-stdlib,stdlib --release
Run by wasmer
wasmer run --dir `pwd` -- target/wasm32-wasip1/release/rustpython.wasm `pwd`/extra_tests/snippets/stdlib_random.py
Run by wapm
$ wapm install rustpython
$ wapm run rustpython
>>>>> 2+2
4
Building the WASI file
You can build the WebAssembly WASI file with:
cargo build --release --target wasm32-wasip1 --features="freeze-stdlib"
Note: we use the
freeze-stdlibto include the standard library inside the binary. You also have to run oncerustup target add wasm32-wasip1.
JIT (Just in time) compiler
RustPython has a very experimental JIT compiler that compile python functions into native code.
Building
By default the JIT compiler isn't enabled, it's enabled with the jit cargo feature.
cargo run --features jit
This requires autoconf, automake, libtool, and clang to be installed.
Using
To compile a function, call __jit__() on it.
def foo():
a = 5
return 10 + a
foo.__jit__() # this will compile foo to native code and subsequent calls will execute that native code
assert foo() == 15
Embedding RustPython into your Rust Applications
Interested in exposing Python scripting in an application written in Rust,
perhaps to allow quickly tweaking logic where Rust's compile times would be inhibitive?
Then examples/hello_embed.rs and examples/mini_repl.rs may be of some assistance.
Disclaimer
RustPython is in development, and while the interpreter certainly can be used in interesting use cases like running Python in WASM and embedding into a Rust project, do note that RustPython is not totally production-ready.
Contribution is more than welcome! See our contribution section for more information on this.
Conference videos
Checkout those talks on conferences:
Use cases
Although RustPython is a fairly young project, a few people have used it to make cool projects:
- GreptimeDB: an open-source, cloud-native, distributed time-series database. Using RustPython for embedded scripting.
- pyckitup: a game engine written in rust.
- Robot Rumble: an arena-based AI competition platform
- Ruff: an extremely fast Python linter, written in Rust
Goals
- Full Python-3 environment entirely in Rust (not CPython bindings)
- A clean implementation without compatibility hacks
Documentation
Currently along with other areas of the project, documentation is still in an early phase.
You can read the online documentation for the latest release, or the user guide.
You can also generate documentation locally by running:
cargo doc # Including documentation for all dependencies
cargo doc --no-deps --all # Excluding all dependencies
Documentation HTML files can then be found in the target/doc directory or you can append --open to the previous commands to
have the documentation open automatically on your default browser.
For a high level overview of the components, see the architecture document.
Contributing
Contributions are welcome and highly appreciated. To get started, check out the contributing guidelines.
You can also join us on Discord.
Compiling to WebAssembly
Community
Chat with us on Discord.
Code of conduct
Our code of conduct can be found here.
Credit
The initial work was based on windelbouwman/rspython and shinglyu/RustPython
Links
These are some useful links to related projects:
- https://github.com/ProgVal/pythonvm-rust
- https://github.com/shinglyu/RustPython
- https://github.com/windelbouwman/rspython
License
This project is licensed under the MIT license. Please see the LICENSE file for more details.
The project logo is licensed under the CC-BY-4.0 license. Please see the LICENSE-logo file for more details.

