How do I accumulate an operation by repeating x nu...

# stdlib

[Sam Stone]

How do I accumulate an operation by repeating x number of times? Essentially, 2.repeat(init = 10) { acc -> acc * 10 } == 1_000 (to repeat 10*10 twice, or 10*10*10) instead of (0..1).fold(10) { acc, _ -> acc * 10 } = 1_000

[ephemient]

one option:

generateSequence(seed = 10)  { acc -> acc * 10 }.drop(2).first() == 1_000

[ephemient]

but I'd just write it with a var and loop; both fold and sequence create unnecessary iterators

[ephemient]

certainly you could write your own

inline fun <T> repeat(times: Int, seed: T, nextFunction: (T) -> T): T {
    var acc = seed
    repeat(times) { acc = nextFunction(acc) }
    return acc
}

but there's no standard function, and unfortunately due to the generic (even though it's inline) this results in unnecessary boxing

[Dominaezzz]

Does the boxing still happen if T is reified ?

[ephemient]

yes, reified just enables some more features