docs(examples): update client example to use rt::main

examples/client.rs

@@ -7,9 +7,12 @@ use std::env;
 use std::io::{self, Write};
 
 use hyper::Client;
-use hyper::rt;
 
-fn main() {
+// A simple type alias so as to DRY.
+type Result<T> = std::result::Result<T, Box<dyn std::error::Error + Send + Sync>>;
+
+#[hyper::rt::main]
+async fn main() -> Result<()> {
     pretty_env_logger::init();
 
     // Some simple CLI args requirements...
@@ -17,7 +20,7 @@ fn main() {
         Some(url) => url,
         None => {
             println!("Usage: client <url>");
-            return;
+            return Ok(());
         }
     };
 
@@ -26,26 +29,16 @@ fn main() {
     let url = url.parse::<hyper::Uri>().unwrap();
     if url.scheme_part().map(|s| s.as_ref()) != Some("http") {
         println!("This example only works with 'http' URLs.");
-        return;
+        return Ok(());
     }
 
-    // Run the runtime with the future trying to fetch and print this URL.
-    //
-    // Note that in more complicated use cases, the runtime should probably
-    // run on its own, and futures should just be spawned into it.
-    rt::run(fetch_url(url));
+    fetch_url(url).await
 }
 
-async fn fetch_url(url: hyper::Uri) {
+async fn fetch_url(url: hyper::Uri) -> Result<()> {
     let client = Client::new();
 
-    let res = match client.get(url).await {
-        Ok(res) => res,
-        Err(err) => {
-            eprintln!("Response Error: {}", err);
-            return;
-        }
-    };
+    let res = client.get(url).await?;
 
     println!("Response: {}", res.status());
     println!("Headers: {:#?}\n", res.headers());
@@ -53,17 +46,11 @@ async fn fetch_url(url: hyper::Uri) {
     let mut body = res.into_body();
 
     while let Some(next) = body.next().await {
-        match next {
-            Ok(chunk) => {
-                io::stdout().write_all(&chunk)
-                    .expect("example expects stdout is open");
-            },
-            Err(err) => {
-                eprintln!("Body Error: {}", err);
-                return;
-            }
-        }
+        let chunk = next?;
+        io::stdout().write_all(&chunk)?;
     }
 
     println!("\n\nDone!");
+
+    Ok(())
 }