Add a merged stream

stream-composition/src/main.rs

@@ -3,10 +3,14 @@ use trpl::{ReceiverStream, Stream, StreamExt};
 
 fn main() {
     trpl::run(async {
-        let mut messages =
+        let messages = get_messages().timeout(Duration::from_millis(200));
-            pin!(get_messages().timeout(Duration::from_millis(200)));
+        let intervals = get_intervals()
+            .map(|count| format!("Interval: {count}"))
+            .timeout(Duration::from_secs(10));
+        let merged = messages.merge(intervals);
+        let mut stream = pin!(merged);
 
-        while let Some(result) = messages.next().await {
+        while let Some(result) = stream.next().await {
             match result {
                 Ok(message) => println!("{message}"),
                 Err(reason) => eprintln!("Problem: {reason:?}"),
@@ -30,3 +34,18 @@ fn get_messages() -> impl Stream<Item = String> {
 
     ReceiverStream::new(rx)
 }
+
+fn get_intervals() -> impl Stream<Item = u32> {
+    let (tx, rx) = trpl::channel();
+
+    trpl::spawn_task(async move {
+        let mut count = 0;
+        loop {
+            trpl::sleep(Duration::from_millis(1)).await;
+            count += 1;
+            tx.send(count).unwrap();
+        }
+    });
+
+    ReceiverStream::new(rx)
+}