A pure-Rust, async-first reimplementation of the JSONata query and transformation language. The engine parses and evaluates JSONata expressions entirely in Rust — no JavaScript runtime involved — and is published on crates.io as async_jsonata_rust.

• Official JSONata test suite: 1651 / 1653 passing. The two remaining cases are test-harness artifacts (a per-case depth/timebox limit the harness doesn't enforce, and a last-digit floating-point rounding difference), not engine bugs.
• Genuinely async. The evaluator is async end-to-end (evaluate_async returns a future); user-defined functions can be async and are awaited cooperatively — it runs under tokio/async-std or any executor. A synchronous evaluate facade is also provided.

[dependencies]
async_jsonata_rust = "0.3"

use async_jsonata_rust::{Evaluator, JsonValue};
use serde_json::json;

let evaluator = Evaluator::with_builtins();
let expr = evaluator.parse("$sum(items.(price * qty))")?;

let input = JsonValue::from_serde_json(&json!({
    "items": [{"price": 10, "qty": 2}, {"price": 5, "qty": 3}]
}));

// Async API (await it on your runtime); a sync `evaluate` exists too.
let out = futures::executor::block_on(evaluator.evaluate_async(&expr, &input))?;
assert_eq!(out.to_serde_json(), Some(json!(35)));
# Ok::<(), async_jsonata_rust::Error>(())

You can register custom (including async) functions via FunctionRegistry. See examples-app/ for a fuller demo: a single complex expression building a report over an orders document, using aggregation, sorting, higher-order functions, lambdas, and a user-registered async $discount function.

• src/jsonata-rust/ — the async_jsonata_rust crate (parser, async evaluator, function registry, public API).
• src/jsonata/ — upstream JSONata LICENSE + test/test-suite/ only (the JSON test cases used as the behavioural oracle).
• examples-app/ — a standalone crate that depends on the published crate from crates.io and runs the demo.
• Dockerfile / compose.yml — a minimal Rust dev container.

The dev container ships the Rust toolchain (the host toolchain is not used).

# Build the dev image
docker compose build dev

# Run all tests (lib + integration + doc; includes the full official suite)
docker compose run --rm --workdir /workspace/src/jsonata-rust dev \
  bash -lc 'export PATH=/workspace/.cargo/bin:/opt/rust/bin:$PATH && cargo test'

# Run the official suite with a per-group summary (optionally pass a group name)
docker compose run --rm --workdir /workspace/src/jsonata-rust dev \
  bash -lc 'export PATH=/workspace/.cargo/bin:/opt/rust/bin:$PATH && cargo run --quiet --example run_suite'

# Run the crates.io demo app (pulls the published crate, not the local sources)
docker compose run --rm examples-app

The official suite is also wired as a regular cargo test (tests/official_suite.rs), so completeness is checked in CI and new upstream cases are picked up automatically.

MIT. The bundled JSONata test suite under src/jsonata/test/test-suite retains its original license (src/jsonata/LICENSE).

• JSONata — the original language, specification, and test suite, maintained by JSONata Limited.