Rust source profile and native APIs

Without surfaces: ["js"], the Rust target uses its native source profile.

Rust primitive aliases

import type { i32, i64, usize } from "@tsonic/rust/types.js";

export function selected(values: i64[], index: usize): i64 {
  return values[index];
}

Rust aliases retain exact source primitive facts. Portable source may instead use int32, int64, and nativeUint from @tsonic/core/types.js.

Standard-library virtual imports

The selected foundation controls which compiler-backed modules are legal:

import { Ordering } from "@tsonic/rust/core/cmp.js";
import { Vec } from "@tsonic/rust/alloc/vec.js";
import { HashMap } from "@tsonic/rust/std/collections.js";

The compiler-provider snapshots the selected Rust toolchain, obtains rustdoc JSON, and exposes only requested public declarations. core source cannot silently use alloc or std; an operation whose closed requirements exceed the selected foundation is rejected before source publication.

Native imports require the selected toolchain’s rust-src component:

rustup component add rust-src

The provider reads rustdoc signature formats 57–60 through one decoder. A different format is rejected rather than interpreted as a known schema. See the native-provider reference for toolchain and cache rules.

Third-party crates

Third-party crates use a user-owned Cargo project. The import names a direct Cargo dependency alias and public module path:

[dependencies]
widget_alias = { package = "acme-widget", version = "1.2.3" }

import type { int32 } from "@tsonic/core/types.js";
import { Widget } from "@tsonic/rust/crates/widget_alias/index.js";

export function create(): Widget<int32> {
  return new Widget<int32>(42);
}

The provider resolves only direct dependencies from the immutable Cargo snapshot. It preserves exact crate, module, item, generic, lifetime, const, associated-type, safety, ABI, and fallibility identities. Unsupported rustdoc signatures fail at the virtual import boundary.

JavaScript surface

Select JavaScript semantics explicitly:

{
  "targets": [{ "id": "rust", "surfaces": ["js"] }]
}

const values = [1, 2, 3];
console.log(values.map((value) => value * 2).join(","));

This activates the shared JS source profile and the Rust JS runtime. Native Rust imports remain available when their foundation permits them.

See the exact source-module reference and native-provider reference.