uniffi-rs

Javascript calling back and forth to Rust which calls in to Kotlin & Swift you say? There are few pieces to put in place here, but it's something we've discussed. The current task is teaching uniffi to support multiple foreign languages at the same time: <https://github.com/mozilla/uniffi-rs/issues/2295>. But, yeah, what we're launching today takes you closer to your dream than it was yesterday. The rest, work is progressing. What we're launching today is

The article provides a very detailed exploration of all of the fun challenges you can face designing FFIs with Rust, but there's a good chance you can "get away" with simpler approaches if you think ahead a bit. In our case, we call into Rust from Kotlin using JNI [0] and Swift using swift-bridge [1]. Thankfully our use case for the FFI [2] is for non-performance-critical calls and the data structures are fairly simple, so we just serialize objects with JSON. No major issues so far. One thing I am surprised hasn't been mentioned so far is Mozilla's UniFFI [3] which seems to solve some of the issues brought up in the article. We plan to switch to that once our FFI requirements become more complex. [0] https://docs.rs/jni/latest/jni/ [1] https://github.com/chinedufn/swift-bridge [2] https://www.firezone.dev/kb/architecture/tech-stack#client

Kinda. Did a dummy project in a few languages to see what I wanted to use for the big project. Looked at Go, Swift, Kotlin MP, and Rust. I liked Kotlin tools, and small binary size. If I knew I wasn't going to need more libraries in the future I might pick it. Go is great, although binaries a bit large with the runtime packed in, and TinyGo too limiting. Rust: I couldn't find a good multi-language binding package so I skipped it... then later found https://github.com/mozilla/uniffi-rs It could be a top contender.