Haven't heard much from Helix since 2017, and it does appear to be inactive since. The limitation to only Strings, Integers, Floats, and Booleans made it pretty hard to use in practice given how Array/Hash/Object-centric Ruby is.

Though the latest Mozilla blog post about Rust FFI using protobufs makes me think rolling the same approach on top of Helix's groundwork with Strings should make it possible to pass around meaningful objects with a bit of overhead.

I use Rutie[0] to handle passing complex ruby objects to Rust and it works well. You can also use Rutie-Serde[1] which handles even more of the heavy lifting for parsing Ruby objects into Rust structs.

[0] https://github.com/danielpclark/rutie [1] https://github.com/deliveroo/rutie-serde