This is because REPLs now require the closure to return `RequestError` instead of a generic error type, so type inference works perfectly for a return value. If you use something other than `RequestError`, you can transfer your code to `teloxide::dispatching`, which still permits a generic error type.
`user.id` now uses `UserId` type, `ChatId` now represents only _chat id_, not channel username, all `chat_id` function parameters now accept `Recipient` (if they allow for channel usernames).
If you used to work with chat/user ids (for example saving them to a database), you may need to change your code to account for new types. Some examples how that may look like:
`RequestError::RetryAfter` now has a field of type `Duration`, instead of `i32`.
### teloxide
The old dispatching system was removed. If you still hasn't moved to the new one, read the [0.5 -> 0.6 migration guide] for more information on this topic. Note that since the old dispatching was removed, the new dispatching system now lives in the `dispatching` module, **not**`dispatching2` module.
If you implement `UpdateListener` yourself, note that `StopToken` is now required to be `Send`.
`BotCommand` trait was renamed to `BotCommands`. `BotCommands::descriptions` not returns `CommandDescriptions` instead of `String`. To get string, you can call `.to_string()`.
`#[derive(DialogueState)]` is deprecated in favour of `teloxide::handler!`, a more flexible API for dealing with dialogues. [`examples/dialogue.rs`](https://github.com/teloxide/teloxide/blob/03521bfd3d68f6f576dcc44b5473aaa5ce9b553f/examples/dialogue.rs) shows how to use it.
In order to make `Dispatcher` implement `Send`, `DispatcherBuilder::{default_handler, error_handler}` now accept handlers that implements `Send + Sync`. If you used `!Send` or `!Sync` handlers here, you may need to change that.
v0.6 of teloxide introduces a new dispatching model based on the [chain of responsibility pattern]. To use it, you need to replace `prelude` with `prelude2` and `dispatching` with `dispatching2`. Instead of using old REPLs, you should now use `teloxide::repls2`.
First of all, now there are no streams. Instead of using streams, you use [`dptree`], which is a more suitable alternative for our purposes. Thus, if you previously used `Dispatcher::messages_handler`, now you should use `Update::filter_message()`, and so on.
Secondly, `Dispatcher` has been split into two separate abstractions: `DispatcherBuilder` and `Dispatcher`. The calling sequence is simple: you call `Dispatcher::builder(bot, handler)`, set up your stuff, and then call `.build()` to obtain `Dispatcher`. Later, you can `.setup_ctrlc_handler()` on it and finally `.dispatch()` (or `.dispatch_with_listener()`).
Lastly, the dialogue management system has been greatly simplified. Just compare the [new `examples/dialogue.rs`](https://github.com/teloxide/teloxide/blob/25f863402d4f377f573ce2ba394f5b768ee8052e/examples/dialogue.rs) with the [old one](https://github.com/teloxide/teloxide/tree/2a6067fe94773a0015627a6aaa1930b8f88b6da0/examples/dialogue_bot/src) to see the difference. Now you don't need `TransitionIn`, `TransitionOut`, `#[teloxide(subtransition)]`, etc. All you need is to derive `DialogueState` for your FSM enumeration, call `.enter_dialogue()` and write handlers for each of a dialogue's states. Instead of supplying dependencies in the `aux` parameter of `Transition::react`, you can just call `.dependencies()` while setting up the dispatcher and all the dependencies will be passed to your handler functions as parameters.
For more information, please look at the appropriate documentation pages and the [updated examples](https://github.com/teloxide/teloxide/tree/master/examples). Note that, in one of the upcoming releases, the old dispatching model will be removed, so we highly encourage you to migrate your bots to the new one.
See also: [teloxide examples fixes](https://github.com/teloxide/teloxide/pull/408/files/369e43aa7ed1b192d326e6bdfe76f3560001353f..18f88cc034e97fd437c48930728c1d5d2da7a14d).
Now it's not required, so you can remove the `Arc`:
```diff
let bot = Bot::new(token).parse_mode(ParseMode::MarkdownV2);
-let bot = Arc::new(bot);
```
### teloxide
#### Mutable reference for dispatching
`Dispatcher::dispatch` and `Dispatcher::dispatch_with_listener` now require mutable (unique) reference to self.
If you've used variable to store `Dispatcher`, you need to make it mutable:
```diff
-let dp = Dispatcher::new();
+let mut dp = Dispatcher::new();
/* ... */
dp.dispatch();
```
#### Listener refactor
`UpdateListener` trait was refactored.
If you've used `polling`/`polling_default` provided by teloxide, no changes are required.
If, however, you've used or implemented `UpdateListener` directly or used a `Stream` as a listener,
then you need to refactor your code too.
See also: [teloxide examples fixes](https://github.com/teloxide/teloxide/pull/385/files/8785b8263cb4caebf212e2a66a19f73e653eb060..c378d6ef4e524da96718beec6f989e8ac51d1531).
#### `polling_default`
`polling_default` is now async, but removes webhook.
