Functional Kotlin

Channels

One way for two coroutines to communicate (or for a coroutine to the external world as with async) is through Deferred<T>:

import kotlinx.coroutines.experimental.delayimport kotlinx.coroutines.experimental.launchimport kotlinx.coroutines.experimental.runBlockingfun main(args: Array<String>) = runBlocking {    val result = CompletableDeferred<String>()   val world = launch {      delay(500)      result.complete("World (from another coroutine)")   }   val hello =launch {      println("Hello ${result.await()}")   }   hello.join()   world.join()}

Deferreds are fine for single values, but sometimes we want to send a sequence or a stream. In that case, we can use Channel. Channel which is similar to BlockingQueue, but with suspending operations instead of blocking ...