Howto use coroutines in M1.3

What is the right way to use coroutines under M1.3 (EAP)?
I am obviously missing some basic ingredience, because coroutine “hello-world”

fun main(args: Array<String>) {
     launch {

will not compile. launch and delay cannot be resolved.

The following are my kotlin related parts from build.gradle.kts

plugins {
    kotlin("jvm") version "1.3.0-rc-116"

apply {

kotlin {
    experimental {
        coroutines = Coroutines.ENABLE

dependencies {

tasks.withType<KotlinCompile> {
    kotlinOptions.jvmTarget = "1.8"

I guess, the experimental part is no longer needed in 1.3.

You need to import launch and delay I believe. They are not keywords in the language, but rather functions defined in some package.

Unfortunately, they are not available as imports (launch will only autocomplete to javafx.application.Application.launch).
Other functions from the corouting package like suspendCoroutine are available, that is why I believe something is missing in the configuration (jvm specific intrinsics?).

You need to add a dependency on kotlinx.coroutines library, where these functions are declared.

The latest version of that library for Kotlin 1.3 is 0.27.0-eap13.

Note that the top-level launch and async functions are deprecated, you can find how to use them properly here: Structured concurrency. Today marks the release of a version… | by Roman Elizarov | Medium


Thank you. It works now.

Reading that article I’m now finally getting a grasp on how to use coroutines in Kotlin 1.3.

The documentation doesn’t seem to do a very good job to me of explaining how to use coroutines other than giving runBlocking() which is not what I wanted, and didn’t do a very good job at all (in my opinion) of explaining how to use GlobalScope or how to use the new version of launch() with a CoroutineScope.

It doesn’t help of course that almost all articles, posts and code examples that one finds are using coroutines from Kotlin 1.1 or 1.2.

I think a few more introductory articles in the manual on how to implement CoroutineScope, how to supply a CoroutineContext, what dispatchers to choose from etc wouldn’t be amiss.