Hello, Does Kotlin have a `scanRight`, a symmetry of `scan`, starting by the end of the collection,...

# getting-started

[xtof]

Hello,

Does Kotlin have a scanRight, a symmetry of scan, starting by the end of the collection, to be consistent with the availability of fold(Right) and reduce(Right)?

Something like

inline fun <R> List<R>.scanRight(initial: R, operation: (acc: R, Int) -> R): List<R>

So I don't need to use .reversed() twice to achieve the same with the (left) scan() that we have like this:

listOf(whatever).reversed().scan(0){acc, e -> operation...}.reversed()

[Stephan Schröder]

Doesn't look like it: https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/-list/ 🤷‍♂️
Maybe you can build it yourself as extension function using foldRight?

[Adam S]

A related hint: there's asReversed(), which should mitigate needing to reverse the list twice

https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/as-reversed.html

[xtof]

I didn't this one, nice, thanks 🙂