none

fun <T> Sequence<T>.none(): Boolean (source)

Returns true if the sequence has no elements.

The operation is terminal.

import kotlin.test.*

fun main(args: Array<String>) {
//sampleStart
val emptyList = emptyList<Int>()
println("emptyList.none() is ${emptyList.none()}") // true

val nonEmptyList = listOf("one", "two", "three")
println("nonEmptyList.none() is ${nonEmptyList.none()}") // false
//sampleEnd
}
inline fun <T> Sequence<T>.none(
    predicate: (T) -> Boolean
): Boolean
(source)

Returns true if no elements match the given predicate.

The operation is terminal.

import kotlin.test.*

fun main(args: Array<String>) {
//sampleStart
val isEven: (Int) -> Boolean = { it % 2 == 0 }
val zeroToTen = 0..10
println("zeroToTen.none { isEven(it) } is ${zeroToTen.none { isEven(it) }}") // false
println("zeroToTen.none(isEven) is ${zeroToTen.none(isEven)}") // false

val odds = zeroToTen.map { it * 2 + 1 }
println("odds.none { isEven(it) } is ${odds.none { isEven(it) }}") // true

val emptyList = emptyList<Int>()
println("emptyList.none { true } is ${emptyList.none { true }}") // true
//sampleEnd
}