PassingDispatcherAsCoroutineContext.kt

fun launch(dispatcher: Dispatcher, block: suspend () -> Unit) {
    val callback = object : Continuation<Unit> {
        // Passing dispatcher as CoroutineContext
        override val context: CoroutineContext = dispatcher
        override fun resumeWith(result: Result<Unit>) {}
    }
    val coroutine = block.createCoroutineUnintercepted(callback)
    when (dispatcher) {
        Dispatcher.Main -> Handler(Looper.getMainLooper()).post {
            coroutine.resumeWith(Result.success(Unit))
        }

        Dispatcher.Background -> thread {
            coroutine.resumeWith(Result.success(Unit))
        }
    }
}

suspend fun doWork() {
    suspendCoroutineUninterceptedOrReturn<Unit> { cont ->
        thread {
            // Retrieve Dispatcher from continuation and resume execution
            when (cont.context as Dispatcher) {
                Dispatcher.Main -> Handler(Looper.getMainLooper()).post {
                    cont.resumeWith(Result.success(Unit))
                }

                Dispatcher.Background -> thread {
                    cont.resumeWith(Result.success(Unit))
                }
            }
        }
        COROUTINE_SUSPENDED
    }
}