example-channel-04.kt

/*
 * Copyright 2016-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
 */

// This file was automatically generated from channels.md by Knit tool. Do not edit.
package kotlinx.coroutines.guide.exampleChannel04

import kotlinx.coroutines.*
import kotlinx.coroutines.channels.*

fun main() = runBlocking {
    val numbers = produceNumbers() // produces integers from 1 and on
    val squares = square(numbers) // squares integers
    repeat(5) {
        println(squares.receive()) // print first five
    }
    println("Done!") // we are done
    coroutineContext.cancelChildren() // cancel children coroutines
}

fun CoroutineScope.produceNumbers() = produce<Int> {
    var x = 1
    while (true) send(x++) // infinite stream of integers starting from 1
}

fun CoroutineScope.square(numbers: ReceiveChannel<Int>): ReceiveChannel<Int> = produce {
    for (x in numbers) send(x * x)
}