add HTTP hello world example

examples/http-hello-world.rs

@@ -0,0 +1,42 @@
+//! HTTP Hello World server
+//!
+//! To make an HTTP request do:
+//!
+//! ```sh
+//! curl http://localhost:8080/foo
+//! ```
+
+use async_std::io;
+use async_std::net::{TcpListener, TcpStream};
+use async_std::prelude::*;
+use async_std::task;
+
+async fn process(stream: &mut TcpStream) -> io::Result<()> {
+    let msg = "HTTP/1.1 200 OK
+Content-Length: 11
+Content-Type: text/plain
+
+hello world";
+    let mut buffer = [0; 512];
+    stream.read(&mut buffer).await?;
+    stream.write_all(msg.as_bytes()).await?;
+
+    Ok(())
+}
+
+fn main() -> io::Result<()> {
+    task::block_on(async {
+        let listener = TcpListener::bind("127.0.0.1:8080").await?;
+        println!("Listening on {}", listener.local_addr()?);
+
+        let mut incoming = listener.incoming();
+
+        while let Some(stream) = incoming.next().await {
+            let mut stream = stream?;
+            task::spawn(async move {
+                process(&mut stream).await.unwrap();
+            });
+        }
+        Ok(())
+    })
+}