This is a simple example of building a rust app via nix, with some C dependencies (GTK).
Clone the repo, then run nix develop to enter a dev shell with the dependencies available, then cargo build (assuming you already have cargo and rust installed on your system).
Or, simply nix run to build and run the app.
You can even run the app without cloning the repo via nix run github:oliverevans96/rust-nix-gtk-hello-world.