For people interested in what’s doing the Kotlin compiler under the hood :ok_hand: Blog post about t...

# coroutines

[Manuel Vivo]

For people interested in what’s doing the Kotlin compiler under the hood 👌 Blog post about this coming along next week

https://www.youtube.com/watch?v=IQf-vtIC-Uc&list=PLWz5rJ2EKKc_T0fSZc9obnmnWcjvmJdw_&index=5▾

[stevecstian]

The return type of the transformed function is actually Any?, not Unit, right?

[Manuel Vivo]

It’s Unit, there’s nothing to return

[Manuel Vivo]

the completion param is used to “return” a value

[stevecstian]

Have you checked https://jakewharton.com/exceptions-and-proxies-and-coroutines-oh-my/#coroutine-implementation-crash-course ? completion seems not the only way to "return" value...

[Manuel Vivo]

Wonder if it’s because of the use of suspendCoroutine

[stevecstian]

I believe @elizarov explained it in this talk before:

https://youtu.be/3xalVUY69Ok▾

, but I can't find the slide now...

[jw]

All suspend functions use Any? as a return type because it's a union type of T | COROUTINE_SUSPENDED

[jw]

This allows code like

suspend fun foo(): String {
  return if (Random.nextBoolean()) {
    4
  } else {
    otherSuspendFunction()
  }
}

to return synchronously when it can. Synchronous exceptions behave similarly.

[Manuel Vivo]

Thanks @jw! Will add that to the the post 👌

[araqnid]

I have an example of calling suspend functions from Java at https://github.com/araqnid/library-versions/blob/master/java/src/main/java/org/araqnid/libraryversions/java/JavaMain.java which illustrates the call interface, if it’s helpful