all

Common
JVM
JS
Native
1.0
inline fun < T > Sequence < T > . all (
predicate : ( T ) -> Boolean
) : Boolean

(source)

Returns true if all elements match the given predicate .

Note that if the sequence contains no elements, the function returns true because there are no elements in it that do not match the predicate. See a more detailed explanation of this logic concept in "Vacuous truth" article.

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.all { isEven(it) } is ${zeroToTen.all { isEven(it) }}") // false
println("zeroToTen.all(isEven) is ${zeroToTen.all(isEven)}") // false

val evens = zeroToTen.map { it * 2 }
println("evens.all { isEven(it) } is ${evens.all { isEven(it) }}") // true

val emptyList = emptyList<Int>()
println("emptyList.all { false } is ${emptyList.all { false }}") // true
//sampleEnd
}