Yes, xi (https://github.com/google/xi-editor) is a text editor written in Rust. It's not exactly an alternative to vim, it's more of a text editor microkernel that can have various different frontends and plugins attached which use JSON-based IPC to allow their implementation in whatever language you want. So, on macOS you can implement the frontend in Swift, and write plugins in Python or Ruby or Rust or whatever you like. On Fuchsia, the frontend is in Flutter.