Stream does not impl Future?

compiler_output.txt

cargo test --test echo
   Compiling rustin v0.1.0 (/rustin)
error[E0277]: the trait bound `dyn futures_core::stream::Stream<Item=std::result::Result<rustin::callback::Action, rustin::error::Error>> + std::marker::Unpin: core::future::future::Future` is not satisfied
  --> tests/echo.rs:16:10
   |
16 |         .then(|result| match result {
   |          ^^^^ the trait `core::future::future::Future` is not implemented for `dyn futures_core::stream::Stream<Item=std::result::Result<rustin::callback::Action, rustin::error::Error>> + std::marker::Unpin`
   |
   = note: required because of the requirements on the impl of `core::future::future::Future` for `std::boxed::Box<dyn futures_core::stream::Stream<Item=std::result::Result<rustin::callback::Action, rustin::error::Error>> + std::marker::Unpin>`

error[E0599]: no method named `into_stream` found for type `futures_util::future::then::Then<std::boxed::Box<dyn core::future::future::Future<Output=std::result::Result<std::option::Option<std::string::String>, <S as rustin::store::Store>::Error>> + std::marker::Unpin>, std::boxed::Box<dyn futures_core::stream::Stream<Item=std::result::Result<rustin::callback::Action, rustin::error::Error>> + std::marker::Unpin>, [closure@tests/echo.rs:16:15: 27:10 message:_, store:_, id:_]>` in the current scope
  --> tests/echo.rs:28:10
   |
28 |         .into_stream()
   |          ^^^^^^^^^^^
   |
   = note: the method `into_stream` exists but the following trait bounds were not satisfied:
           `&futures_util::future::then::Then<std::boxed::Box<dyn core::future::future::Future<Output=std::result::Result<std::option::Option<std::string::String>, <S as rustin::store::Store>::Error>> + std::marker::Unpin>, std::boxed::Box<dyn futures_core::stream::Stream<Item=std::result::Result<rustin::callback::Action, rustin::error::Error>> + std::marker::Unpin>, [closure@tests/echo.rs:16:15: 27:10 message:_, store:_, id:_]> : futures_util::future::FutureExt`
           `&futures_util::future::then::Then<std::boxed::Box<dyn core::future::future::Future<Output=std::result::Result<std::option::Option<std::string::String>, <S as rustin::store::Store>::Error>> + std::marker::Unpin>, std::boxed::Box<dyn futures_core::stream::Stream<Item=std::result::Result<rustin::callback::Action, rustin::error::Error>> + std::marker::Unpin>, [closure@tests/echo.rs:16:15: 27:10 message:_, store:_, id:_]> : futures_util::try_stream::TryStreamExt`
           `&mut futures_util::future::then::Then<std::boxed::Box<dyn core::future::future::Future<Output=std::result::Result<std::option::Option<std::string::String>, <S as rustin::store::Store>::Error>> + std::marker::Unpin>, std::boxed::Box<dyn futures_core::stream::Stream<Item=std::result::Result<rustin::callback::Action, rustin::error::Error>> + std::marker::Unpin>, [closure@tests/echo.rs:16:15: 27:10 message:_, store:_, id:_]> : futures_util::future::FutureExt`
           `&mut futures_util::future::then::Then<std::boxed::Box<dyn core::future::future::Future<Output=std::result::Result<std::option::Option<std::string::String>, <S as rustin::store::Store>::Error>> + std::marker::Unpin>, std::boxed::Box<dyn futures_core::stream::Stream<Item=std::result::Result<rustin::callback::Action, rustin::error::Error>> + std::marker::Unpin>, [closure@tests/echo.rs:16:15: 27:10 message:_, store:_, id:_]> : futures_util::try_stream::TryStreamExt`
           `futures_util::future::then::Then<std::boxed::Box<dyn core::future::future::Future<Output=std::result::Result<std::option::Option<std::string::String>, <S as rustin::store::Store>::Error>> + std::marker::Unpin>, std::boxed::Box<dyn futures_core::stream::Stream<Item=std::result::Result<rustin::callback::Action, rustin::error::Error>> + std::marker::Unpin>, [closure@tests/echo.rs:16:15: 27:10 message:_, store:_, id:_]> : futures_util::future::FutureExt`
           `futures_util::future::then::Then<std::boxed::Box<dyn core::future::future::Future<Output=std::result::Result<std::option::Option<std::string::String>, <S as rustin::store::Store>::Error>> + std::marker::Unpin>, std::boxed::Box<dyn futures_core::stream::Stream<Item=std::result::Result<rustin::callback::Action, rustin::error::Error>> + std::marker::Unpin>, [closure@tests/echo.rs:16:15: 27:10 message:_, store:_, id:_]> : futures_util::try_stream::TryStreamExt`

error: aborting due to 2 previous errors

Some errors occurred: E0277, E0599.
For more information about an error, try `rustc --explain E0277`.
error: Could not compile `rustin`.

To learn more, run the command again with --verbose.

echo.rs

use futures::{
    future::ok,
    prelude::*,
    stream::{empty, once},
};
use rustin::{message::IncomingMessage, store::Store, ActionStream};

fn echo<S>(message: &IncomingMessage, store: &mut S) -> ActionStream
where
    S: Store,
{
    let id = message.user().id();

    store
        .get(id)
        .then(|result| match result {
            Ok(Some(id)) => Box::new(once(ok(message.reply(format!(
                "Hello again, {}!",
                message.user().name().unwrap_or(&id)
            ))))) as ActionStream,
            Ok(None) => {
                store.set(id, "1");

                Box::new(empty()) as ActionStream
            }
            _ => panic!("store error"),
        })
        .into_stream()
}