I recently participated in the GNOME / Rust “dev sprint” in Mexico City. (A thousand thanks to Federico and Joaquin for organizing!) While there I spent some time working on the gnome-class plugin. The goal of gnome-class was to make it easy to write GObject implementations in Rust which would fully interoperate with C code. Roughly speaking, my goal was that you should be able to write code that looked and felt like Vala code, but where the method bodies (and types, and so forth) are in Rust.