is there any utility method that repeatedly calls ...

# getting-started

[Bernhard]

is there any utility method that repeatedly calls a lambda on itself for n times? E.g.
2.repeat(3) { it + 1 } would add +1 to 3 2 times

[Ruckus]

Not in the stdlib as far as I know, but that's pretty easy to write yourself:

inline fun <T> T.repeat(
    count: Int,
    action: (T) -> T,
): T {
    var x = this
    kotlin.repeat(count) {
        x = action(x)
    }
    return x
}

[Bernhard]

yeah, that's what I did, but did not know about kotlin.repeat, thanks

[Bernhard]

fun <T> Int.repeat(initial: T, block: (T) -> T): T {
    var accumulator = initial
    kotlin.repeat(this) {
        accumulator = block(accumulator)
    }
    return accumulator
}

[Ruckus]

Ah, you have the count out front. In that case you might want to go with a different name to not confuse it with Kotlin's repeat signature, but that's just a personal preference.

[Bernhard]

thank you

[Ruckus]

Maybe something along the lines of fold (e.g. foldN?) since that's probably closer in meaning to what you're doing.
(compare Kotlin's various fold functions)

[Youssef Shoaib [MOD]]

You could also do (0..2).fold(3) { it, _ -> it + 1 } but it's kinda ugly because it passes the index in

[Klitos Kyriacou]

Another way: generateSequence(3) { it + 1 }.take(1 + 2).last() (it's 1 + 2 because the seed (3) is counted as the first element, and you want another 2).

[ephemient]

why not just

generateSequence(3) { it + 1 }.elementAt(2)