Leverage new AsyncFn traits in stream module

futures/src/stream.rs

@@ -8,13 +8,10 @@ use futures::stream::{self, Stream, StreamExt};
 /// This is a more ergonomic [`stream::unfold`], which allows you to go
 /// from the "world of futures" to the "world of streams" by simply looping
 /// and publishing to an async channel from inside a [`Future`].
-pub fn channel<T, F>(
+pub fn channel<T>(
     size: usize,
-    f: impl FnOnce(mpsc::Sender<T>) -> F,
+    f: impl AsyncFnOnce(mpsc::Sender<T>),
-) -> impl Stream<Item = T>
+) -> impl Stream<Item = T> {
-where
-    F: Future<Output = ()>,
-{
     let (sender, receiver) = mpsc::channel(size);
 
     let runner = stream::once(f(sender)).filter_map(|_| async { None });
@@ -24,13 +21,10 @@ where
 
 /// Creates a new [`Stream`] that produces the items sent from a [`Future`]
 /// that can fail to the [`mpsc::Sender`] provided to the closure.
-pub fn try_channel<T, E, F>(
+pub fn try_channel<T, E>(
     size: usize,
-    f: impl FnOnce(mpsc::Sender<T>) -> F,
+    f: impl AsyncFnOnce(mpsc::Sender<T>) -> Result<(), E>,
-) -> impl Stream<Item = Result<T, E>>
+) -> impl Stream<Item = Result<T, E>> {
-where
-    F: Future<Output = Result<(), E>>,
-{
     let (sender, receiver) = mpsc::channel(size);
 
     let runner = stream::once(f(sender)).filter_map(|result| async {

futures/src/subscription.rs

@@ -161,7 +161,7 @@ impl<T> Subscription<T> {
     /// }
     ///
     /// fn some_worker() -> impl Stream<Item = Event> {
-    ///     stream::channel(100, |mut output| async move {
+    ///     stream::channel(100, async |mut output| {
     ///         // Create channel
     ///         let (sender, mut receiver) = mpsc::channel(100);
     ///