Repeating Sequences in Kotlin

CoRepeat.kt

// Version using experimental co-routines in 1.1 thanks to @voddan on Slack
import kotlin.coroutines.experimental.buildSequence

fun <T> Sequence<T>.repeat() : Sequence<T> = buildSequence {
    while(true) yieldAll(this@repeat)
}

fun main(args: Array<String>) {
    sequenceOf(1, 2, 3).repeat().take(6).forEach { i -> println(i) }
}

Repeat.kt

class RepeatingSequence<T> constructor(val sequence : Sequence<T>) : Sequence<T> {
    override fun iterator(): Iterator<T> = object : Iterator<T> {
        var iterator = sequence.iterator()
        override fun next(): T {
            val result = iterator.next()
            if (!iterator.hasNext()) {
                iterator = sequence.iterator()
            }
            return result
        }

        override fun hasNext(): Boolean {
            return iterator.hasNext()
        }
    }
}

fun <T> Sequence<T>.repeat() : Sequence<T> = RepeatingSequence(this)

fun main(args: Array<String>) {
    sequenceOf(1, 2, 3).repeat().take(6).forEach { i -> println(i) }
}