为什么是 'futures::prelude::*; 未申报的

Question

出于某种原因，它告诉我，当我尝试遵循 rust 中的 IRC 示例时，它是未声明的，并且它不起作用是没有意义的，因为我以前使用过这样的库并且它以前工作过，所以我不知道是什么正在发生\

代码：

use futures::prelude::*;
use irc::client::prelude::*;

#[tokio::main]
async fn main() -> irc::error::Result<()> {
    let config = Config {
        nickname: Some("pickles".to_owned()),
        server: Some("chat.freenode.net".to_owned()),
        channels: vec!["#rust-spam".to_owned()],
        ..Default::default()
    };

    let mut client = Client::from_config(config).await?;
    client.identify()?;

    let mut stream = client.stream()?;
    let sender = client.sender();

    while let Some(message) = stream.next().await.transpose()? {
        print!("{}", message);

        match message.command {
            Command::PRIVMSG(ref target, ref msg) => {
                if msg.contains(client.current_nickname()) {
                    sender.send_privmsg(target, "Hi!")?;
                }
            }
            _ => (),
        }
    }

    Ok(())
}

错误

 --> src\main.rs:1:5
  |
1 | use futures::prelude::*;
  |     ^^^^^^^ use of undeclared type or module `futures`

error[E0308]: mismatched types
 --> src\main.rs:9:19
  |
9 |         channels: vec!["#rust-spam".to_owned()],
  |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |                   |
  |                   expected enum `std::option::Option`, found struct `std::vec::Vec`
  |                   help: try using a variant of the expected enum: `Some(<[_]>::into_vec(box [$($x),+]))`
  |
  = note: expected enum `std::option::Option<std::vec::Vec<_>>`
           found struct `std::vec::Vec<_>`
  = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0599]: no function or associated item named `from_config` found for trait object `dyn irc::client::Client` in the current scope
  --> src\main.rs:13:30
   |
13 |     let mut client = Client::from_config(config).await?;
   |                              ^^^^^^^^^^^ function or associated item not found in `dyn irc::client::Client`

Cargo.toml

[package]
name = "irc"
version = "0.1.0"
authors = ["sudo"]
edition = "2018"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
irc = "0.13"
tokio = { version = "0.2.22", features = ["full"] }

编辑：添加了 Cargo.toml

Answer 1

您需要将期货箱添加到您的货物文件中。例如来自文档

[dependencies]
futures = "0.3"