review handlers section

content/docs/handlers.md

@@ -6,12 +6,12 @@ weight: 160
 
 # Request Handlers
 
-A request handler is a function that accepts zero or more parameters that can be extracted
+A request handler is an async function that accepts zero or more parameters that can be extracted
 from a request (ie, [*impl FromRequest*][implfromrequest]) and returns a type that can
 be converted into an HttpResponse (ie, [*impl Responder*][implresponder]).
 
 Request handling happens in two stages. First the handler object is called, returning any
-object that implements the [*Responder*][respondertrait] trait.  Then, `respond_to()` is
+object that implements the [*Responder*][respondertrait] trait. Then, `respond_to()` is
 called on the returned object, converting itself to a `HttpResponse` or `Error`.
 
 By default actix-web provides `Responder` implementations for some standard types,
@@ -22,13 +22,13 @@ such as `&'static str`, `String`, etc.
 Examples of valid handlers:
 
 ```rust
-fn index(_req: HttpRequest) -> &'static str {
+async fn index(_req: HttpRequest) -> &'static str {
     "Hello world!"
 }
 ```
 
 ```rust
-fn index(_req: HttpRequest) -> String {
+async fn index(_req: HttpRequest) -> String {
     "Hello world!".to_owned()
 }
 ```
@@ -37,13 +37,13 @@ You can also change the signature to return `impl Responder` which works well if
 complex types are involved.
 
 ```rust
-fn index(_req: HttpRequest) -> impl Responder {
+async fn index(_req: HttpRequest) -> impl Responder {
     Bytes::from_static(b"Hello world!")
 }
 ```
 
 ```rust
-fn index(req: HttpRequest) -> Box<Future<Item=HttpResponse, Error=Error>> {
+async fn index(req: HttpRequest) -> Box<Future<Item=HttpResponse, Error=Error>> {
     ...
 }
 ```
@@ -56,28 +56,13 @@ Let's create a response for a custom type that serializes to an `application/jso
 
 {{< include-example example="responder-trait" file="main.rs" section="responder-trait" >}}
 
-## Async handlers
+## Streaming response body
 
-There are two different types of async handlers. Response objects can be generated asynchronously
-or more precisely, any type that implements the [*Responder*][respondertrait] trait.
-
-In this case, the handler must return a `Future` object that resolves to the *Responder* type, i.e:
-
-{{< include-example example="async-handlers" file="main.rs" section="async-responder" >}}
-
-Or the response body can be generated asynchronously. In this case, body must implement
+Response body can be generated asynchronously. In this case, body must implement
 the stream trait `Stream<Item=Bytes, Error=Error>`, i.e:
 
 {{< include-example example="async-handlers" file="stream.rs" section="stream" >}}
 
-Both methods can be combined. (i.e Async response with streaming body)
-
-It is possible to return a `Result` where the `Result::Item` type can be `Future`.  In
-this example, the `index` handler can return an error immediately or return a future
-that resolves to a `HttpResponse`.
-
-{{< include-example example="async-handlers" file="async_stream.rs" section="async-stream" >}}
-
 ## Different return types (Either)
 
 Sometimes, you need to return different types of responses. For example, you can error