kotlin-stdlib/kotlin.sequences/ifEmpty

ifEmpty

fun <T> Sequence<T>.ifEmpty(defaultValue: () -> Sequence<T>): Sequence<T>(source)

Returns a sequence that iterates through the elements either of this sequence or, if this sequence turns out to be empty, of the sequence returned by defaultValue function.

Since Kotlin

1.3

Samples

import kotlin.test.*

fun main() { 
   //sampleStart 
   val empty = emptySequence<Int>()

val emptyOrDefault = empty.ifEmpty { sequenceOf("default") }
println(emptyOrDefault.toList()) // [default]

val nonEmpty = sequenceOf("value")

val nonEmptyOrDefault = nonEmpty.ifEmpty { sequenceOf("default") }
println(nonEmptyOrDefault.toList()) // [value] 
   //sampleEnd
}