kotlin-stdlib/kotlin.sequences/all

all

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.

Since Kotlin

1.0

Samples

import kotlin.test.*

fun main() { 
   //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
}