Rust looks great, I'm not using it but learning and it look fantastic.
I have one question, I guess off-topic: Rust uses LLVM, like Swift, Julia etc. Could these LLVM languages interoperate better because of this common foundation? Maybe link using LLVM IR instead of C ABI FFI, or something like that?
LLVM has so many little ways to configure its output, and unless two LLVM users configure the outputs to be compatible, they are unlikely to be. LLVM is more of a toolset with some language than a shared infrastructure.