Trait futures::prelude::Future

#[must_use = "futures do nothing unless polled"]
pub trait Future {
    type Output;
    fn poll(self: Pin<&mut Self>, waker: &Waker) -> Poll<Self::Output>;
}

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

A future represents an asynchronous computation.

A future is a value that may not have finished computing yet. This kind of "asynchronous value" makes it possible for a thread to continue doing useful work while it waits for the value to become available.

The poll method

The core method of future, poll, attempts to resolve the future into a final value. This method does not block if the value is not ready. Instead, the current task is scheduled to be woken up when it's possible to make further progress by polling again. The wake up is performed using the waker argument of the poll() method, which is a handle for waking up the current task.

When using a future, you generally won't call poll directly, but instead await! the value.

Associated Types

type Output

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futures in libcore are unstable

The type of value produced on completion.

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Required methods

fn poll(self: Pin<&mut Self>, waker: &Waker) -> Poll<Self::Output>

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futures in libcore are unstable

Attempt to resolve the future to a final value, registering the current task for wakeup if the value is not yet available.

Return value

This function returns:

• Poll::Pending if the future is not ready yet
• Poll::Ready(val) with the result val of this future if it finished successfully.

Once a future has finished, clients should not poll it again.

When a future is not ready yet, poll returns Poll::Pending and stores a clone of the Waker to be woken once the future can make progress. For example, a future waiting for a socket to become readable would call .clone() on the Waker and store it. When a signal arrives elsewhere indicating that the socket is readable, [Waker::wake] is called and the socket future's task is awoken. Once a task has been woken up, it should attempt to poll the future again, which may or may not produce a final value.

Note that on multiple calls to poll, only the most recent Waker passed to poll should be scheduled to receive a wakeup.

Runtime characteristics

Futures alone are inert; they must be actively polled to make progress, meaning that each time the current task is woken up, it should actively re-poll pending futures that it still has an interest in.

The poll function is not called repeatedly in a tight loop -- instead, it should only be called when the future indicates that it is ready to make progress (by calling wake()). If you're familiar with the poll(2) or select(2) syscalls on Unix it's worth noting that futures typically do not suffer the same problems of "all wakeups must poll all events"; they are more like epoll(4).

An implementation of poll should strive to return quickly, and should not block. Returning quickly prevents unnecessarily clogging up threads or event loops. If it is known ahead of time that a call to poll may end up taking awhile, the work should be offloaded to a thread pool (or something similar) to ensure that poll can return quickly.

An implementation of poll may also never cause memory unsafety.

Panics

Once a future has completed (returned Ready from poll), then any future calls to poll may panic, block forever, or otherwise cause any kind of bad behavior except causing memory unsafety. The Future trait itself provides no guarantees about the behavior of poll after a future has completed.

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Implementations on Foreign Types

impl<F> Future for AssertUnwindSafe<F> where
    F: Future, 

type Output = <F as Future>::Output

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futures in libcore are unstable

fn poll(
    self: Pin<&mut AssertUnwindSafe<F>>,
    waker: &Waker
) -> Poll<<AssertUnwindSafe<F> as Future>::Output>

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futures in libcore are unstable

impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized, 

type Output = <F as Future>::Output

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fn poll(
    self: Pin<&mut &'_ mut F>,
    waker: &Waker
) -> Poll<<&'_ mut F as Future>::Output>

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impl<P> Future for Pin<P> where
    P: Unpin + DerefMut,
    <P as Deref>::Target: Future, 

type Output = <<P as Deref>::Target as Future>::Output

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fn poll(
    self: Pin<&mut Pin<P>>,
    waker: &Waker
) -> Poll<<Pin<P> as Future>::Output>

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impl<F> Future for Box<F> where
    F: Unpin + Future + ?Sized, 

type Output = <F as Future>::Output

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fn poll(
    self: Pin<&mut Box<F>>,
    waker: &Waker
) -> Poll<<Box<F> as Future>::Output>

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impl<Fut, T> Future for UnitError<Fut> where
    Fut: Future<Output = T>, 

type Output = Result<T, ()>

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fn poll(self: Pin<&mut UnitError<Fut>>, waker: &Waker) -> Poll<Result<T, ()>>

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impl<St> Future for TryConcat<St> where
    St: TryStream,
    <St as TryStream>::Ok: Extend<<<St as TryStream>::Ok as IntoIterator>::Item>,
    <St as TryStream>::Ok: IntoIterator,
    <St as TryStream>::Ok: Default, 

type Output = Result<<St as TryStream>::Ok, <St as TryStream>::Error>

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fn poll(
    self: Pin<&mut TryConcat<St>>,
    waker: &Waker
) -> Poll<<TryConcat<St> as Future>::Output>

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impl<St, Fut, F> Future for TryForEachConcurrent<St, Fut, F> where
    F: FnMut(<St as TryStream>::Ok) -> Fut,
    Fut: Future<Output = Result<(), <St as TryStream>::Error>>,
    St: TryStream, 

type Output = Result<(), <St as TryStream>::Error>

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fn poll(
    self: Pin<&mut TryForEachConcurrent<St, Fut, F>>,
    waker: &Waker
) -> Poll<<TryForEachConcurrent<St, Fut, F> as Future>::Output>

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impl<'a, St> Future for SelectNextSome<'a, St> where
    St: Unpin + Stream + FusedStream, 

type Output = <St as Stream>::Item

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fn poll(
    self: Pin<&mut SelectNextSome<'a, St>>,
    waker: &Waker
) -> Poll<<SelectNextSome<'a, St> as Future>::Output>

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impl<St, Fut, F> Future for ForEachConcurrent<St, Fut, F> where
    F: FnMut(<St as Stream>::Item) -> Fut,
    Fut: Future<Output = ()>,
    St: Stream, 

type Output = ()

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fn poll(
    self: Pin<&mut ForEachConcurrent<St, Fut, F>>,
    waker: &Waker
) -> Poll<()>

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Implementors

impl<'_, A> Future for ReadToEnd<'_, A> where
    A: AsyncRead + ?Sized, 

type Output = Result<(), Error>

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fn poll(
    self: Pin<&mut ReadToEnd<'_, A>>,
    waker: &Waker
) -> Poll<<ReadToEnd<'_, A> as Future>::Output>

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impl<'_, R> Future for Read<'_, R> where
    R: AsyncRead + ?Sized, 

type Output = Result<usize, Error>

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futures in libcore are unstable

fn poll(
    self: Pin<&mut Read<'_, R>>,
    waker: &Waker
) -> Poll<<Read<'_, R> as Future>::Output>

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impl<'_, R> Future for ReadExact<'_, R> where
    R: AsyncRead + ?Sized, 

type Output = Result<(), Error>

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fn poll(
    self: Pin<&mut ReadExact<'_, R>>,
    waker: &Waker
) -> Poll<<ReadExact<'_, R> as Future>::Output>

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impl<'_, R, W> Future for CopyInto<'_, R, W> where
    R: AsyncRead + ?Sized,
    W: AsyncWrite + ?Sized, 

type Output = Result<u64, Error>

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fn poll(
    self: Pin<&mut CopyInto<'_, R, W>>,
    waker: &Waker
) -> Poll<<CopyInto<'_, R, W> as Future>::Output>

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impl<'_, Si> Future for futures::sink::Close<'_, Si> where
    Si: Unpin + Sink + ?Sized, 

type Output = Result<(), <Si as Sink>::SinkError>

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fn poll(
    self: Pin<&mut Close<'_, Si>>,
    waker: &Waker
) -> Poll<<Close<'_, Si> as Future>::Output>

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impl<'_, Si> Future for futures::sink::Flush<'_, Si> where
    Si: Unpin + Sink + ?Sized, 

type Output = Result<(), <Si as Sink>::SinkError>

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fn poll(
    self: Pin<&mut Flush<'_, Si>>,
    waker: &Waker
) -> Poll<<Flush<'_, Si> as Future>::Output>

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impl<'_, Si> Future for Send<'_, Si> where
    Si: Unpin + Sink + ?Sized, 

type Output = Result<(), <Si as Sink>::SinkError>

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fn poll(
    self: Pin<&mut Send<'_, Si>>,
    waker: &Waker
) -> Poll<<Send<'_, Si> as Future>::Output>

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impl<'_, Si, St> Future for SendAll<'_, Si, St> where
    Si: Unpin + Sink + ?Sized,
    St: Stream<Item = <Si as Sink>::SinkItem> + Unpin + ?Sized, 

type Output = Result<(), <Si as Sink>::SinkError>

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fn poll(
    self: Pin<&mut SendAll<'_, Si, St>>,
    waker: &Waker
) -> Poll<<SendAll<'_, Si, St> as Future>::Output>

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impl<'_, St> Future for Next<'_, St> where
    St: Unpin + Stream, 

type Output = Option<<St as Stream>::Item>

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fn poll(
    self: Pin<&mut Next<'_, St>>,
    waker: &Waker
) -> Poll<<Next<'_, St> as Future>::Output>

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impl<'_, St> Future for TryNext<'_, St> where
    St: Unpin + TryStream, 

type Output = Result<Option<<St as TryStream>::Ok>, <St as TryStream>::Error>

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fn poll(
    self: Pin<&mut TryNext<'_, St>>,
    waker: &Waker
) -> Poll<<TryNext<'_, St> as Future>::Output>

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impl<'_, W> Future for futures::io::Close<'_, W> where
    W: AsyncWrite + ?Sized, 

type Output = Result<(), Error>

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fn poll(
    self: Pin<&mut Close<'_, W>>,
    waker: &Waker
) -> Poll<<Close<'_, W> as Future>::Output>

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impl<'_, W> Future for futures::io::Flush<'_, W> where
    W: AsyncWrite + ?Sized, 

type Output = Result<(), Error>

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fn poll(
    self: Pin<&mut Flush<'_, W>>,
    waker: &Waker
) -> Poll<<Flush<'_, W> as Future>::Output>

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impl<'_, W> Future for WriteAll<'_, W> where
    W: AsyncWrite + ?Sized, 

type Output = Result<(), Error>

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fn poll(
    self: Pin<&mut WriteAll<'_, W>>,
    waker: &Waker
) -> Poll<Result<(), Error>>

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impl<'a, T> Future for FutureObj<'a, T>

type Output = T

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fn poll(self: Pin<&mut FutureObj<'a, T>>, waker: &Waker) -> Poll<T>

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impl<'a, T> Future for LocalFutureObj<'a, T>

type Output = T

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fn poll(self: Pin<&mut LocalFutureObj<'a, T>>, waker: &Waker) -> Poll<T>

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impl<'a, T> Future for MutexLockFuture<'a, T>

type Output = MutexGuard<'a, T>

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fn poll(
    self: Pin<&mut MutexLockFuture<'a, T>>,
    waker: &Waker
) -> Poll<<MutexLockFuture<'a, T> as Future>::Output>

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impl<F> Future for JoinAll<F> where
    F: Future, 

type Output = Vec<<F as Future>::Output>

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fn poll(
    self: Pin<&mut JoinAll<F>>,
    waker: &Waker
) -> Poll<<JoinAll<F> as Future>::Output>

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futures in libcore are unstable

impl<F> Future for OptionFuture<F> where
    F: Future, 

type Output = Option<<F as Future>::Output>

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fn poll(
    self: Pin<&mut OptionFuture<F>>,
    waker: &Waker
) -> Poll<<OptionFuture<F> as Future>::Output>

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impl<F> Future for TryJoinAll<F> where
    F: TryFuture, 

type Output = Result<Vec<<F as TryFuture>::Ok>, <F as TryFuture>::Error>

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fn poll(
    self: Pin<&mut TryJoinAll<F>>,
    waker: &Waker
) -> Poll<<TryJoinAll<F> as Future>::Output>

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impl<Fut> Future for MaybeDone<Fut> where
    Fut: Future, 

type Output = ()

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fn poll(
    self: Pin<&mut MaybeDone<Fut>>,
    waker: &Waker
) -> Poll<<MaybeDone<Fut> as Future>::Output>

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impl<Fut> Future for Abortable<Fut> where
    Fut: Future, 

type Output = Result<<Fut as Future>::Output, Aborted>

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fn poll(
    self: Pin<&mut Abortable<Fut>>,
    waker: &Waker
) -> Poll<<Abortable<Fut> as Future>::Output>

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impl<Fut> Future for CatchUnwind<Fut> where
    Fut: Future + UnwindSafe, 

type Output = Result<<Fut as Future>::Output, Box<dyn Any + 'static + Send>>

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fn poll(
    self: Pin<&mut CatchUnwind<Fut>>,
    waker: &Waker
) -> Poll<<CatchUnwind<Fut> as Future>::Output>

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impl<Fut> Future for Flatten<Fut> where
    Fut: Future,
    <Fut as Future>::Output: Future, 

type Output = <<Fut as Future>::Output as Future>::Output

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fn poll(
    self: Pin<&mut Flatten<Fut>>,
    waker: &Waker
) -> Poll<<Flatten<Fut> as Future>::Output>

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impl<Fut> Future for Fuse<Fut> where
    Fut: Future, 

type Output = <Fut as Future>::Output

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fn poll(
    self: Pin<&mut Fuse<Fut>>,
    waker: &Waker
) -> Poll<<Fut as Future>::Output>

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impl<Fut> Future for IntoFuture<Fut> where
    Fut: TryFuture, 

type Output = Result<<Fut as TryFuture>::Ok, <Fut as TryFuture>::Error>

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fn poll(
    self: Pin<&mut IntoFuture<Fut>>,
    waker: &Waker
) -> Poll<<IntoFuture<Fut> as Future>::Output>

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impl<Fut> Future for Remote<Fut> where
    Fut: Future, 

type Output = ()

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fn poll(self: Pin<&mut Remote<Fut>>, waker: &Waker) -> Poll<()>

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impl<Fut> Future for Shared<Fut> where
    Fut: Future,
    <Fut as Future>::Output: Clone, 

type Output = <Fut as Future>::Output

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fn poll(
    self: Pin<&mut Shared<Fut>>,
    waker: &Waker
) -> Poll<<Shared<Fut> as Future>::Output>

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impl<Fut, E> Future for ErrInto<Fut, E> where
    Fut: TryFuture,
    <Fut as TryFuture>::Error: Into<E>, 

type Output = Result<<Fut as TryFuture>::Ok, E>

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fn poll(
    self: Pin<&mut ErrInto<Fut, E>>,
    waker: &Waker
) -> Poll<<ErrInto<Fut, E> as Future>::Output>

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impl<Fut, F> Future for Inspect<Fut, F> where
    F: FnOnce(&<Fut as Future>::Output),
    Fut: Future, 

type Output = <Fut as Future>::Output

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fn poll(
    self: Pin<&mut Inspect<Fut, F>>,
    waker: &Waker
) -> Poll<<Fut as Future>::Output>

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impl<Fut, F> Future for UnwrapOrElse<Fut, F> where
    F: FnOnce(<Fut as TryFuture>::Error) -> <Fut as TryFuture>::Ok,
    Fut: TryFuture, 

type Output = <Fut as TryFuture>::Ok

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fn poll(
    self: Pin<&mut UnwrapOrElse<Fut, F>>,
    waker: &Waker
) -> Poll<<UnwrapOrElse<Fut, F> as Future>::Output>

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impl<Fut, F, E> Future for MapErr<Fut, F> where
    F: FnOnce(<Fut as TryFuture>::Error) -> E,
    Fut: TryFuture, 

type Output = Result<<Fut as TryFuture>::Ok, E>

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fn poll(
    self: Pin<&mut MapErr<Fut, F>>,
    waker: &Waker
) -> Poll<<MapErr<Fut, F> as Future>::Output>

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impl<Fut, F, T> Future for Map<Fut, F> where
    F: FnOnce(<Fut as Future>::Output) -> T,
    Fut: Future, 

type Output = T

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fn poll(self: Pin<&mut Map<Fut, F>>, waker: &Waker) -> Poll<T>

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impl<Fut, F, T> Future for MapOk<Fut, F> where
    F: FnOnce(<Fut as TryFuture>::Ok) -> T,
    Fut: TryFuture, 

type Output = Result<T, <Fut as TryFuture>::Error>

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fn poll(
    self: Pin<&mut MapOk<Fut, F>>,
    waker: &Waker
) -> Poll<<MapOk<Fut, F> as Future>::Output>

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impl<Fut1, Fut2> Future for Join<Fut1, Fut2> where
    Fut1: Future,
    Fut2: Future, 

type Output = (<Fut1 as Future>::Output, <Fut2 as Future>::Output)

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fn poll(
    self: Pin<&mut Join<Fut1, Fut2>>,
    waker: &Waker
) -> Poll<<Join<Fut1, Fut2> as Future>::Output>

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impl<Fut1, Fut2> Future for TryJoin<Fut1, Fut2> where
    Fut1: TryFuture,
    Fut2: TryFuture<Error = <Fut1 as TryFuture>::Error>, 

type Output = Result<(<Fut1 as TryFuture>::Ok, <Fut2 as TryFuture>::Ok), <Fut1 as TryFuture>::Error>

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fn poll(
    self: Pin<&mut TryJoin<Fut1, Fut2>>,
    waker: &Waker
) -> Poll<<TryJoin<Fut1, Fut2> as Future>::Output>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<Fut1, Fut2, F> Future for AndThen<Fut1, Fut2, F> where
    F: FnOnce(<Fut1 as TryFuture>::Ok) -> Fut2,
    Fut1: TryFuture,
    Fut2: TryFuture<Error = <Fut1 as TryFuture>::Error>, 

type Output = Result<<Fut2 as TryFuture>::Ok, <Fut2 as TryFuture>::Error>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(
    self: Pin<&mut AndThen<Fut1, Fut2, F>>,
    waker: &Waker
) -> Poll<<AndThen<Fut1, Fut2, F> as Future>::Output>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<Fut1, Fut2, F> Future for OrElse<Fut1, Fut2, F> where
    F: FnOnce(<Fut1 as TryFuture>::Error) -> Fut2,
    Fut1: TryFuture,
    Fut2: TryFuture<Ok = <Fut1 as TryFuture>::Ok>, 

type Output = Result<<Fut2 as TryFuture>::Ok, <Fut2 as TryFuture>::Error>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(
    self: Pin<&mut OrElse<Fut1, Fut2, F>>,
    waker: &Waker
) -> Poll<<OrElse<Fut1, Fut2, F> as Future>::Output>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<Fut1, Fut2, F> Future for Then<Fut1, Fut2, F> where
    F: FnOnce(<Fut1 as Future>::Output) -> Fut2,
    Fut1: Future,
    Fut2: Future, 

type Output = <Fut2 as Future>::Output

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(
    self: Pin<&mut Then<Fut1, Fut2, F>>,
    waker: &Waker
) -> Poll<<Fut2 as Future>::Output>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<Fut1, Fut2, Fut3> Future for Join3<Fut1, Fut2, Fut3> where
    Fut1: Future,
    Fut2: Future,
    Fut3: Future, 

type Output = (<Fut1 as Future>::Output, <Fut2 as Future>::Output, <Fut3 as Future>::Output)

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(
    self: Pin<&mut Join3<Fut1, Fut2, Fut3>>,
    waker: &Waker
) -> Poll<<Join3<Fut1, Fut2, Fut3> as Future>::Output>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<Fut1, Fut2, Fut3> Future for TryJoin3<Fut1, Fut2, Fut3> where
    Fut1: TryFuture,
    Fut2: TryFuture<Error = <Fut1 as TryFuture>::Error>,
    Fut3: TryFuture<Error = <Fut1 as TryFuture>::Error>, 

type Output = Result<(<Fut1 as TryFuture>::Ok, <Fut2 as TryFuture>::Ok, <Fut3 as TryFuture>::Ok), <Fut1 as TryFuture>::Error>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(
    self: Pin<&mut TryJoin3<Fut1, Fut2, Fut3>>,
    waker: &Waker
) -> Poll<<TryJoin3<Fut1, Fut2, Fut3> as Future>::Output>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<Fut1, Fut2, Fut3, Fut4> Future for Join4<Fut1, Fut2, Fut3, Fut4> where
    Fut1: Future,
    Fut2: Future,
    Fut3: Future,
    Fut4: Future, 

type Output = (<Fut1 as Future>::Output, <Fut2 as Future>::Output, <Fut3 as Future>::Output, <Fut4 as Future>::Output)

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(
    self: Pin<&mut Join4<Fut1, Fut2, Fut3, Fut4>>,
    waker: &Waker
) -> Poll<<Join4<Fut1, Fut2, Fut3, Fut4> as Future>::Output>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<Fut1, Fut2, Fut3, Fut4> Future for TryJoin4<Fut1, Fut2, Fut3, Fut4> where
    Fut1: TryFuture,
    Fut2: TryFuture<Error = <Fut1 as TryFuture>::Error>,
    Fut3: TryFuture<Error = <Fut1 as TryFuture>::Error>,
    Fut4: TryFuture<Error = <Fut1 as TryFuture>::Error>, 

type Output = Result<(<Fut1 as TryFuture>::Ok, <Fut2 as TryFuture>::Ok, <Fut3 as TryFuture>::Ok, <Fut4 as TryFuture>::Ok), <Fut1 as TryFuture>::Error>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(
    self: Pin<&mut TryJoin4<Fut1, Fut2, Fut3, Fut4>>,
    waker: &Waker
) -> Poll<<TryJoin4<Fut1, Fut2, Fut3, Fut4> as Future>::Output>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<Fut1, Fut2, Fut3, Fut4, Fut5> Future for Join5<Fut1, Fut2, Fut3, Fut4, Fut5> where
    Fut1: Future,
    Fut2: Future,
    Fut3: Future,
    Fut4: Future,
    Fut5: Future, 

type Output = (<Fut1 as Future>::Output, <Fut2 as Future>::Output, <Fut3 as Future>::Output, <Fut4 as Future>::Output, <Fut5 as Future>::Output)

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(
    self: Pin<&mut Join5<Fut1, Fut2, Fut3, Fut4, Fut5>>,
    waker: &Waker
) -> Poll<<Join5<Fut1, Fut2, Fut3, Fut4, Fut5> as Future>::Output>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<Fut1, Fut2, Fut3, Fut4, Fut5> Future for TryJoin5<Fut1, Fut2, Fut3, Fut4, Fut5> where
    Fut1: TryFuture,
    Fut2: TryFuture<Error = <Fut1 as TryFuture>::Error>,
    Fut3: TryFuture<Error = <Fut1 as TryFuture>::Error>,
    Fut4: TryFuture<Error = <Fut1 as TryFuture>::Error>,
    Fut5: TryFuture<Error = <Fut1 as TryFuture>::Error>, 

type Output = Result<(<Fut1 as TryFuture>::Ok, <Fut2 as TryFuture>::Ok, <Fut3 as TryFuture>::Ok, <Fut4 as TryFuture>::Ok, <Fut5 as TryFuture>::Ok), <Fut1 as TryFuture>::Error>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(
    self: Pin<&mut TryJoin5<Fut1, Fut2, Fut3, Fut4, Fut5>>,
    waker: &Waker
) -> Poll<<TryJoin5<Fut1, Fut2, Fut3, Fut4, Fut5> as Future>::Output>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<R, F> Future for Lazy<F> where
    F: FnOnce(&Waker) -> R, 

type Output = R

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(self: Pin<&mut Lazy<F>>, waker: &Waker) -> Poll<R>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<St> Future for Concat<St> where
    St: Stream,
    <St as Stream>::Item: Extend<<<St as Stream>::Item as IntoIterator>::Item>,
    <St as Stream>::Item: IntoIterator,
    <St as Stream>::Item: Default, 

type Output = <St as Stream>::Item

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(
    self: Pin<&mut Concat<St>>,
    waker: &Waker
) -> Poll<<Concat<St> as Future>::Output>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<St> Future for StreamFuture<St> where
    St: Unpin + Stream, 

type Output = (Option<<St as Stream>::Item>, St)

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(
    self: Pin<&mut StreamFuture<St>>,
    waker: &Waker
) -> Poll<<StreamFuture<St> as Future>::Output>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<St, C> Future for Collect<St, C> where
    C: Default + Extend<<St as Stream>::Item>,
    St: Stream, 

type Output = C

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(self: Pin<&mut Collect<St, C>>, waker: &Waker) -> Poll<C>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<St, C> Future for TryCollect<St, C> where
    C: Default + Extend<<St as TryStream>::Ok>,
    St: TryStream, 

type Output = Result<C, <St as TryStream>::Error>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(
    self: Pin<&mut TryCollect<St, C>>,
    waker: &Waker
) -> Poll<<TryCollect<St, C> as Future>::Output>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<St, Fut, F> Future for ForEach<St, Fut, F> where
    F: FnMut(<St as Stream>::Item) -> Fut,
    Fut: Future<Output = ()>,
    St: Stream, 

type Output = ()

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(self: Pin<&mut ForEach<St, Fut, F>>, waker: &Waker) -> Poll<()>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<St, Fut, F> Future for TryForEach<St, Fut, F> where
    F: FnMut(<St as TryStream>::Ok) -> Fut,
    Fut: TryFuture<Ok = (), Error = <St as TryStream>::Error>,
    St: TryStream, 

type Output = Result<(), <St as TryStream>::Error>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(
    self: Pin<&mut TryForEach<St, Fut, F>>,
    waker: &Waker
) -> Poll<<TryForEach<St, Fut, F> as Future>::Output>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<St, Fut, T, F> Future for Fold<St, Fut, T, F> where
    F: FnMut(T, <St as Stream>::Item) -> Fut,
    Fut: Future<Output = T>,
    St: Stream, 

type Output = T

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(self: Pin<&mut Fold<St, Fut, T, F>>, waker: &Waker) -> Poll<T>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<St, Fut, T, F> Future for TryFold<St, Fut, T, F> where
    F: FnMut(T, <St as TryStream>::Ok) -> Fut,
    Fut: TryFuture<Ok = T, Error = <St as TryStream>::Error>,
    St: TryStream, 

type Output = Result<T, <St as TryStream>::Error>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(
    self: Pin<&mut TryFold<St, Fut, T, F>>,
    waker: &Waker
) -> Poll<<TryFold<St, Fut, T, F> as Future>::Output>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<St, Si> Future for Forward<St, Si> where
    Si: Sink + Unpin,
    St: Stream<Item = Result<<Si as Sink>::SinkItem, <Si as Sink>::SinkError>>, 

type Output = Result<Si, <Si as Sink>::SinkError>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(
    self: Pin<&mut Forward<St, Si>>,
    waker: &Waker
) -> Poll<<Forward<St, Si> as Future>::Output>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<T> Future for Receiver<T>

type Output = Result<T, Canceled>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(self: Pin<&mut Receiver<T>>, waker: &Waker) -> Poll<Result<T, Canceled>>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<T> Future for Empty<T>

type Output = T

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(self: Pin<&mut Empty<T>>, &Waker) -> Poll<T>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<T> Future for Ready<T>

type Output = T

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(self: Pin<&mut Ready<T>>, _waker: &Waker) -> Poll<T>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<T> Future for RemoteHandle<T> where
    T: 'static + Send, 

type Output = T

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(self: Pin<&mut RemoteHandle<T>>, waker: &Waker) -> Poll<T>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

impl<T, F> Future for PollFn<F> where
    F: FnMut(&Waker) -> Poll<T>, 

type Output = T

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

fn poll(self: Pin<&mut PollFn<F>>, waker: &Waker) -> Poll<T>

🔬 This is a nightly-only experimental API. (futures_api)

futures in libcore are unstable

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