is there a more idiomatic way to write a map with loop like this ``` val flowed = allShapes map var p = it for i in 0 until STRETCH ITERATIONS p = flow p p ```

val flowed = allShapes.map {
            var p = it
            for (i in 0 until STRETCH_ITERATIONS) {
                p = flow(p)
            }
            p
        }

ephemient

08/09/2022, 3:20 PM

Copy code

allShapes.map {
    (0 until STRETCH_ITERATIONS).fold(it) { p, _ ->
        fold(p)
    }
}

Jonathan Ellis

08/09/2022, 3:21 PM

TIL about fold, thanks!

Joffrey

08/09/2022, 5:27 PM

Also, when a for loop is about repeating something some number of times, it's better expressed with the

repeat(n) { ... }

function. So in a case where

fold

wouldn't be a solution to your problem, you could at least replace the loop:

Copy code

val flowed = allShapes.map {
    var p = it
    repeat(STRETCH_ITERATIONS) {
        p = flow(p)
    }
    p
}

ephemient

08/09/2022, 5:40 PM

"better" is arguable; you can't break early out of

repeat

, and the

rangeTo

in a

for

loop is intrinsified so it doesn't cost anything more than

repeat

Joffrey

08/09/2022, 5:43 PM

Of course if you need complex control flow like

break

and

continue

, it's not possible. But such cases would probably not be better expressed by

repeat

anyway - it's not about repeating something N times if you break early.

Jonathan Ellis

08/09/2022, 5:44 PM

it's pretty common to write "loop until condition or a maximum of N times"

Joffrey

08/09/2022, 5:47 PM

Yes, but it's not the case here. My point is, if what you need is a plain "repeat N times" (like here),

repeat

is very clear and meant for this. But of course

repeat

is for repeating, not for other stuff. That said, I have not needed a for loop in Kotlin for quite some time, there usually are clearer alternatives for most use cases.

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