Primitive flow

PrimitiveFlow.kt

import kotlinx.coroutines.runBlocking
import java.util.concurrent.atomic.AtomicInteger

interface Flow<out T> {
    suspend fun collect(collector: FlowCollector<T>)
}

fun interface FlowCollector<in T> {
    suspend fun emit(value: T)
}

fun <T> primitiveFlow(block: suspend FlowCollector<T>.() -> Unit): Flow<T> = object : Flow<T> {
    override suspend fun collect(collector: FlowCollector<T>) = block(collector)
}

fun main() = runBlocking {
    val counter = AtomicInteger(0)
    val flow = primitiveFlow {
        counter.incrementAndGet()
        emit("a")
        emit("b")
        emit("c")
    }
    flow.collect {
        println(it)
    }
    println("Flow was collected ${counter.get()} time")
    flow.collect {
        println(it)
    }
    println("Flow was collected ${counter.get()} times")
}