This is a Kotlin Multiplatform line-by-line transliteration port of rayon.

Original Project: This port is based on rayon. All design credit and project intent belong to the upstream authors; this repository is a faithful port to Kotlin Multiplatform with no behavioural changes intended.

This is an in-progress port. The goal is feature parity with the upstream Rust crate while providing a native Kotlin Multiplatform API. Every Kotlin file carries a // port-lint: source <path> header naming its upstream Rust counterpart so the AST-distance tool can track provenance.

The text below is reproduced from https://github.com/rayon-rs/rayon. It is the upstream project's own description and remains under the upstream authors' authorship; links have been rewritten to absolute upstream URLs where appropriate so they continue to resolve from this repository.

Rayon is a data-parallelism library for Rust. It is extremely lightweight and makes it easy to convert a sequential computation into a parallel one. It also guarantees data-race freedom. (You may also enjoy this blog post about Rayon, which gives more background and details about how it works, or this video, from the Rust Belt Rust conference.) Rayon is available on crates.io, and API documentation is available on docs.rs.

Rayon makes it drop-dead simple to convert sequential iterators into parallel ones: usually, you just change your foo.iter() call into foo.par_iter(), and Rayon does the rest:

use rayon::prelude::*;
fn sum_of_squares(input: &[i32]) -> i32 {
    input.par_iter() // <-- just change that!
         .map(|&i| i * i)
         .sum()
}

Parallel iterators take care of deciding how to divide your data into tasks; it will dynamically adapt for maximum performance. If you need more flexibility than that, Rayon also offers the join and scope functions, which let you create parallel tasks on your own. For even more control, you can create custom threadpools rather than using Rayon's default, global threadpool.

You may have heard that parallel execution can produce all kinds of crazy bugs. Well, rest easy. Rayon's APIs all guarantee data-race freedom, which generally rules out most parallel bugs (though not all). In other words, if your code compiles, it typically does the same thing it did before.

For the most, parallel iterators in particular are guaranteed to produce the same results as their sequential counterparts. One caveat: If your iterator has side effects (for example, sending methods to other threads through a Rust channel or writing to disk), those side effects may occur in a different order. Note also that, in some cases, parallel iterators offer alternative versions of the sequential iterator methods that can have higher performance.

Rayon is available on crates.io. The recommended way to use it is to add a line into your Cargo.toml such as:

[dependencies]
rayon = "1.7"

To use the parallel iterator APIs, a number of traits have to be in scope. The easiest way to bring those things into scope is to use the Rayon prelude. In each module where you would like to use the parallel iterator APIs, just add:

use rayon::prelude::*;

Rayon currently requires rustc 1.59.0 or greater.

Rayon can work on the Web via WebAssembly, but requires an adapter and some project configuration to account for differences between WebAssembly threads and threads on the other platforms.

Check out the wasm-bindgen-rayon docs for more details.

Rayon is an open source project! If you'd like to contribute to Rayon, check out the list of "help wanted" issues. These are all (or should be) issues that are suitable for getting started, and they generally include a detailed set of instructions for what to do. Please ask questions if anything is unclear! Also, check out the Guide to Development page on the wiki. Note that all code submitted in PRs to Rayon is assumed to be licensed under Rayon's dual MIT/Apache 2.0 licensing.

To see Rayon in action, check out the rayon-demo directory, which includes a number of demos of code using Rayon. For example, run this command to get a visualization of an N-body simulation. To see the effect of using Rayon, press s to run sequentially and p to run in parallel.

> cd rayon-demo
> cargo run --release -- nbody visualize

For more information on demos, try:

> cd rayon-demo
> cargo run --release -- --help

See the Rayon FAQ.

Rayon is distributed under the terms of both the MIT license and the Apache License (Version 2.0). See LICENSE-APACHE and LICENSE-MIT for details. Opening a pull request is assumed to signal agreement with these licensing terms.

dependencies {
    implementation("io.github.kotlinmania:rayon-kotlin:1.7.1")
}

./gradlew build
./gradlew test

• macOS arm64
• Linux x64
• Windows mingw-x64
• iOS arm64 / simulator-arm64 (Swift export + XCFramework)
• JS (browser + Node.js)
• Wasm-JS (browser + Node.js)
• Android (API 24+)

See AGENTS.md and CLAUDE.md for translator discipline, port-lint header convention, and Rust → Kotlin idiom mapping.

This Kotlin port is distributed under the same license terms as the upstream rayon. See LICENSE (and any sibling LICENSE-* / NOTICE files mirrored from upstream) for the full text.

Original work copyrighted by the rayon authors.
Kotlin port: Copyright (c) 2026 Sydney Renee and The Solace Project.

Thanks to the rayon maintainers and contributors for the original Rust implementation. This port reproduces their work in Kotlin Multiplatform; bug reports about upstream design or behavior should go to the upstream repository.