mlx-c-rust 0.32.3-alpha.1

A complete, low-level, policy-free Rust bridge to the MLX-C API of Apple's MLX for Apple silicon. Version = the verified MLX release (0.32.3; binds MLX-C 0.7).
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mlx-c-rust

A complete, low-level, policy-free Rust bridge to the public MLX-C C API of Apple's MLX array framework for Apple silicon.

Current release: 0.32.3-alpha.1 — verified against MLX v0.32.3, binding the complete MLX-C v0.7.0 surface. The crate version always names the MLX release it is verified against — the number you search for and install — while the bound MLX-C release is recorded here and in COVERAGE_INVENTORY.md.

The goal

MLX-C exposes the full power of MLX through a stable C Application Programming Interface. This crate binds every public symbol that API declares — not a demand-driven subset — so any capability Apple ships is callable from Rust the day the pin moves. Completeness is enforced, not aspirational: the vendored headers are bindgen-translated in full, and the bridged-symbol inventory they produce feeds a coverage contract that fails when a new MLX-C release adds or removes surface.

The design keeps the crate at one job:

  • Complete: every function, type, and enum variant in the vendored MLX-C headers has a Rust path in.
  • Low-level: thin, predictable wrappers over the C calls; no neural-network modules, optimizers, or model loading.
  • Policy-free: no memory limits, no Metal library path selection, no scheduling opinions. Bring your own policy on top.
  • Exact ownership: array and stream handles are move-only with deterministic release — when a handle drops, its C resource is released, with no hidden reference counting to surprise memory-sensitive code.
  • Errors, not exits: MLX-C's non-terminating error handler is captured thread-locally and surfaced as MlxCError values carrying the attempted operation and MLX's reported description.

What this crate is not: a high-level framework. For neural-network layers, optimizers, and model utilities, look at mlx-rs. The two projects occupy different layers and can be used side by side.

Status

Early public extraction, versioned to mirror the vendored MLX-C release (crate 0.7.0 binds MLX-C v0.7.0, MLX v0.32.3). The bridge was hardened inside a production local-model serving stack before extraction. The completeness guarantee covers symbol presence; per-wrapper behavioral test coverage is growing and tracked in COVERAGE_INVENTORY.md.

Building

Requirements: a Rust toolchain (pinned in rust-toolchain.toml), Clang for bindgen, and an MLX-C library to link against.

Bindgen always runs against the headers vendored under vendor/mlx-c/ — no network, no system headers. For linking a binary that uses the crate, the build script looks for MLX-C in this order:

  1. MLX_C_RUST_MLX_C_PREFIX — a prefix with lib/ containing the library and, if needed, include/.
  2. pkg-config mlx-c.

If neither is found the crate still checks and compiles (documentation builds work); linking a test or binary then reports undefined symbols until MLX-C is provided. Building MLX and MLX-C from source is a CMake build of the upstream repositories; see their documentation.

Versioning

The crate version names the MLX release it is verified against (the scheme mlx-rs established for user-facing crates): crate 0.32.3.x is verified against MLX v0.32.3. The bound MLX-C release rides in the README headline and COVERAGE_INVENTORY.md. Both upstreams are pre-1.0, so minor releases may carry breaking changes when upstream does; our own fixes and same-MLX MLX-C surface changes ride as patch bumps.

Attribution

The fallible-closure error channel — a payload trampoline parking its typed failure in a thread-local slot that the caller's status check prefers over MLX-C's own status error — adopts the pattern used by mlx-rs (MIT OR Apache-2.0). The pattern is adopted; no mlx-rs code is included. MLX and MLX-C are © Apple Inc., MIT licensed.

License

Dual licensed under MIT or Apache-2.0 at your option, matching the widest Rust ecosystem norms. Contribution happens under the same terms.