/// A poll API intended to let users wait for I/O events on multiple handles
/// at once.
interface poll {
    /// A "pollable" handle.
    resource pollable;

    /// Poll for completion on a set of pollables.
    ///
    /// This function takes a list of pollables, which identify I/O sources of
    /// interest, and waits until one or more of the events is ready for I/O.
    ///
    /// The result `list<u32>` contains one or more indices of handles in the
    /// argument list that is ready for I/O.
    ///
    /// If the list contains more elements than can be indexed with a `u32`
    /// value, this function traps.
    ///
    /// A timeout can be implemented by adding a pollable from the
    /// wasi-clocks API to the list.
    ///
    /// This function does not return a `result`; polling in itself does not
    /// do any I/O so it doesn't fail. If any of the I/O sources identified by
    /// the pollables has an error, it is indicated by marking the source as
    /// being reaedy for I/O.
    poll-list: func(in: list<borrow<pollable>>) -> list<u32>;

    /// Poll for completion on a single pollable.
    ///
    /// This function is similar to `poll-list`, but operates on only a single
    /// pollable. When it returns, the handle is ready for I/O.
    poll-one: func(in: borrow<pollable>);
}