oxython

oxython is a Rust-flavoured syntax for Cython, maintained as a series of patches on top of upstream Cython rather than as a fork.

# distances.oxy
use libc::math::sqrt

struct Point:
    f64 x
    f64 y

fn f64 norm(&Point p) noexcept:
    return sqrt(p.x * p.x + p.y * p.y)

fn distances(i32 n):
    let auto total = 0.0
    for i in 0..n:
        total += norm(Point { x = i, y = 1 })
    return total

oxython code lives in .oxy modules, .oxd declaration files and .oxi includes. fn replaces def. Plain .pyx and .pxd files, including Cython's own headers, are untouched, and .pyx modules can cimport from .oxd files. See docs/syntax.md for the full language reference.

Layout

Using it

git clone --recursive https://github.com/oxython/oxython
cd oxython
scripts/apply.sh            # applies patches/ on top of upstream/
pip install ./upstream      # installs the patched Cython

Working on it

The patches are developed as commits on the oxython branch inside upstream/, one commit per patch.

scripts/apply.sh                    # rebuild the branch from patches/
# edit upstream/Cython/..., then commit or amend inside upstream/
scripts/test.sh                     # run the oxython tests (C and C++)
scripts/refresh.sh                  # write the commits back to patches/

To move to a newer Cython, bump the submodule, run scripts/apply.sh, fix any patch that no longer applies with git am --3way, then run scripts/refresh.sh. CI checks the series against upstream master every night, so breakage shows up early.

CI also runs upstream's own test suite with CYTHON_FORCE_OXYTHON=1, which parses every Cython file in oxython mode. That checks that the new syntax stays a strict superset of existing Cython.

Patches

1. .oxy, .oxd and .oxi files, the oxython lexer and a compatibility switch
2. Builtin types: i32, u8, f64, usize, ...
3. true/false and typed literals: 10u8, 2.5f32
4. #[...] attributes
5. Items: fn, let, let auto, static, const, type, struct, union, enum, pub, extern from
6. use imports
7. :: paths
8. Reference and pointer types: &T, &mut T, &&T, r&T, r&mut T
9. loop:
10. Ranges: a..b, a..=b, seq[a..b]
11. Struct expressions: Point { x = 1, y = 2 }
12. fn replaces def

Roadmap

These designs from the original fork are not ported yet: if let and while let, impl blocks, mod, mut bindings, scoped enums, #[repr(packed)], function pointer type syntax, and the dereference and spread operators.

License

Apache License 2.0, the same as Cython. See LICENSE.