responder docs

3.0/docs/async/promise-future.md

@@ -121,6 +121,21 @@ futureUsername.then { username in
 }
 ```
 
+## Futures without promise
+
+In some scenarios you're required to return a `Future` where a `Promise` isn't necessary as you already have the result.
+
+In these scenarios you can initialize a future with the already completed result.
+
+```swift
+// Already completed on initialization
+let future = Future("Hello world!")
+
+future.then { string in
+  print(string)
+}
+```
+
 ## For synchronous APIs
 
 Sometimes, an API needs to be used synchronously in a synchronous envinronment.

3.0/docs/http/responder.md

@@ -0,0 +1,21 @@
+# Responder
+
+Responders are a type capable of [responding](response.md) to a [Request](request.md).
+
+Responders are always [async](../async/promise-future.md) by returning a `Future<Response>` by either transforming/mapping an existing future or creating it's own promise.
+
+## Implementing a static Responder
+
+```swift
+struct StaticResponder: Responder {
+  let response: Response
+
+  init(response: Response) {
+    self.response = response
+  }
+
+  func respond(to req: Request) throws -> Future<Response> {
+    return Future(response)
+  }
+}
+```