Flow — Cold Async Streams

import kotlinx.coroutines.*
import kotlinx.coroutines.flow.*

fun tickerFlow(): Flow<Int> = flow {
    var i = 0
    while (true) {
        emit(i++)
        delay(100)
    }
}

fun main() = runBlocking {
    // Take the first 5 ticks
    tickerFlow().take(5).collect { println("tick: $it") }

    // Transform — same operators as List + lazy/async semantics
    val sumOfFiveSquares = (1..5).asFlow()
        .map { it * it }
        .reduce { acc, n -> acc + n }
    println(sumOfFiveSquares)               // 55

    // Concurrent: produce + consume in parallel
    launch {
        tickerFlow()
            .take(3)
            .collect { println("worker: $it") }
    }
}