Fix more compilation errors in the book

Author: Stjepan Glavina

docs/src/concepts/futures.md

@@ -67,7 +67,7 @@ Note that this return value talks about the past. The past has a drawback: all d
 But we wanted to abstract over *computation* and let someone else choose how to run it. That's fundamentally incompatible with looking at the results of previous computation all the time. So, let's find a type that *describes* a computation without running it. Let's look at the function again:
 
 ```rust,edition2018
-# use std::{fs::File, io::{self, Read}};
+# use std::{fs::File, io, io::prelude::*};
 #
 fn read_file(path: &str) -> io::Result<String> {
     let mut file = File::open(path)?;

docs/src/tutorial/accept_loop.md

@@ -29,7 +29,7 @@ Now we can write the server's accept loop:
 # extern crate async_std;
 # use async_std::{
 #     net::{TcpListener, ToSocketAddrs},
-#     prelude::Stream,
+#     prelude::*,
 # };
 #
 # type Result<T> = std::result::Result<T, Box<dyn std::error::Error + Send + Sync>>;
@@ -66,7 +66,7 @@ Finally, let's add main:
 # extern crate async_std;
 # use async_std::{
 #     net::{TcpListener, ToSocketAddrs},
-#     prelude::Stream,
+#     prelude::*,
 #     task,
 # };
 #

docs/src/tutorial/connecting_readers_and_writers.md

@@ -15,9 +15,8 @@ The order of events "Bob sends message to Alice" and "Alice joins" is determined
 # extern crate futures_channel;
 # extern crate futures_util;
 # use async_std::{
-#     io::{Write},
 #     net::TcpStream,
-#     prelude::{Future, Stream},
+#     prelude::*,
 #     task,
 # };
 # use futures_channel::mpsc;

docs/src/tutorial/handling_disconnection.md

@@ -72,7 +72,7 @@ We use the `select` macro for this purpose:
 # extern crate async_std;
 # extern crate futures_channel;
 # extern crate futures_util;
-# use async_std::{io::Write, net::TcpStream};
+# use async_std::{net::TcpStream, prelude::*};
 use futures_channel::mpsc;
 use futures_util::{select, FutureExt, StreamExt};
 # use std::sync::Arc;
@@ -125,8 +125,9 @@ The final code looks like this:
 # extern crate futures_channel;
 # extern crate futures_util;
 use async_std::{
-    io::{BufReader, BufRead, Write},
+    io::BufReader,
     net::{TcpListener, TcpStream, ToSocketAddrs},
+    prelude::*,
     task,
 };
 use futures_channel::mpsc;

docs/src/tutorial/implementing_a_client.md

@@ -18,8 +18,9 @@ With async, we can just use the `select!` macro.
 # extern crate async_std;
 # extern crate futures_util;
 use async_std::{
-    io::{stdin, BufRead, BufReader, Write},
+    io::{stdin, BufReader},
     net::{TcpStream, ToSocketAddrs},
+    prelude::*,
     task,
 };
 use futures_util::{select, FutureExt, StreamExt};

docs/src/tutorial/receiving_messages.md

@@ -10,9 +10,9 @@ We need to:
 ```rust,edition2018
 # extern crate async_std;
 # use async_std::{
-#     io::{BufRead, BufReader},
+#     io::BufReader,
 #     net::{TcpListener, TcpStream, ToSocketAddrs},
-#     prelude::Stream,
+#     prelude::*,
 #     task,
 # };
 #
@@ -75,9 +75,9 @@ We can "fix" it by waiting for the task to be joined, like this:
 # #![feature(async_closure)]
 # extern crate async_std;
 # use async_std::{
-#     io::{BufRead, BufReader},
+#     io::BufReader,
 #     net::{TcpListener, TcpStream, ToSocketAddrs},
-#     prelude::Stream,
+#     prelude::*,
 #     task,
 # };
 #
@@ -125,7 +125,7 @@ So let's use a helper function for this:
 # extern crate async_std;
 # use async_std::{
 #     io,
-#     prelude::Future,
+#     prelude::*,
 #     task,
 # };
 fn spawn_and_log_error<F>(fut: F) -> task::JoinHandle<()>

docs/src/tutorial/sending_messages.md

@@ -16,9 +16,8 @@ if Alice and Charley send two messages to Bob at the same time, Bob will see the
 # extern crate futures_channel;
 # extern crate futures_util;
 # use async_std::{
-#     io::Write,
 #     net::TcpStream,
-#     prelude::Stream,
+#     prelude::*,
 # };
 use futures_channel::mpsc; // 1
 use futures_util::sink::SinkExt;