Hey! Is there a native Kotlin function like dropWh...

# getting-started

[Eric Joseph]

Hey! Is there a native Kotlin function like dropWhile that doesn’t create a new list?

[Nicolai C.]

What are you trying to achieve exactly? Do you want a mutating function, or chaining? If you want chaining without intermediary collections, you can use the asSequence function. Kotlin generally prefers immutable collections, and non-mutating functions.

Or perhaps some of the remove-like functions on MutableCollection would be of use to you?

[Eric Joseph]

I want to process and remove items from a mutable list so that, once all processing is complete, the original list ends up empty, like my custom extension drain() at right.

[Daniel Pitts]

Maybe you want the .removeIf method?

[Eric Joseph]

removeIf works perfectly, thank you!

[Eric Joseph]

thank for the answers ❤️

[Daniel Pitts]

Fair point.

[Daniel Pitts]

Maybe also consider using indexOf and subList() as alternatives

[Eric Joseph]

However, dropWhile doesn’t modify the list in place; it returns a new one. In other contexts, it works fine too.

[gildor]

All Kotlin collection functions create new list, it's intentional to avoid mutability

[Daniel Pitts]

Personally, I only switch to mutable lists when there is a proven performance concern, or if the size of the list is known to be "huge" (subjectively).

[gildor]

Yep, exactly, the same reason why many collection utils do not exist for Array, that it concidered more low level
So I think it's really a matter to have minimal list of utils for mutable primitives, because they not intended to be used as often and extensively as read only