[RUST] Functions that are exception to uniformity of return type (forever loops, break, exits ...)

divergent_functions.rs

/// Taken from "Programming Rust" by Jim Blandy and Jason Orendorff

// Expressions that don’t finish normally are assigned the special type ! ,
// and they’re exempt from the rules about types having to match.
// You can see ! in the function signature of `std::process::exit()`:
fn exit(code: i32) -> !

// The ! means that exit() never returns. It’s a divergent function.
// You can write divergent functions of your own using the same syntax,
// and this is perfectly natural in some cases:
fn serve_forever(socket: ServerSocket, handler: ServerHandler) -> ! {
  socket.listen();
  loop {
    let s = socket.accept();
    handler.handle(s);
  }
}