runningReduce
inline
fun
CharSequence
.
runningReduce
(
operation
:
(
acc
:
Char
,
Char
)
->
Char
)
:
List
<
Char
>
(source)
Returns a list containing successive accumulation values generated by applying operation from left to right to each character and current accumulator value that starts with the first character of this char sequence.
Note that
acc
value passed to
operation
function should not be mutated;
otherwise it would affect the previous value in resulting list.
import kotlin.test.*
fun main(args: Array<String>) {
//sampleStart
val strings = listOf("a", "b", "c", "d")
println(strings.runningReduce { acc, string -> acc + string }) // [a, ab, abc, abcd]
println(strings.runningReduceIndexed { index, acc, string -> acc + string + index }) // [a, ab1, ab1c2, ab1c2d3]
println(emptyList<String>().runningReduce { _, _ -> "X" }) // []
//sampleEnd
}
Parameters
operation
- function that takes current accumulator value and a character, and calculates the next accumulator value.