hello.rs

fn main() {
  do RoutedServer::serve |config, router| {
    config.listen("127.0.0.1", 1337);

    router.get("/hello", |_,res| res.write("hello world"));

    router.get("/posts/:id", |req,res| {
      res.write(format!("post {}", req.params["id"]))
    });
  }
}

Line 3 was a bug. Line 8 probably should have a semicolon but write() returns () so it doesn't matter.