reduce

Accumulates value starting with the first element and applying operation from left to right to current accumulator value and each element.

inline fun <S, T : S> Sequence<T>.reduce(operation: (acc: S, T) -> S): S(source)

val numbers = sequenceOf(1, 2, 3, 4, 5)
val sum = numbers.reduce { acc, n -> acc + n }
println(sum)  // Output: 15

Source