Want to understand (more deeply) the purpose of

buildList

and family. To me it's semantics instead of (the written-on-phone hence untested block)

mutableListOf<Int>().run {
    add(1)
    this as List<Int>
}

Here're the advantages I see: 1. `buildList`'s usage, semantically, is clearer 2. No need to cast (but can just specify the type somewhere) 3.

buildList

(after the work on the Builder annotation) can infer types so no need to specify any types explicitly Am I missing something else? Pure judgment call here, but isn't the work on

ListBuilder

and builder annotation too much just for this? Only point 3 to me seems that worth it to include directly in the language

buildList

behaves more like

mutableListOf<Int>().run {
    add(1)
}.toList()

because the resulting list is actually immutable, not just by the

List

type, but also by overriding the mutation methods (since the underlying

java.util.List

interface methods may be accessed despite the

kotlin.collections.List

interface not containing them)

So efficiency is a goal too. Not sure what

flow

builder is (and Google not helping)

https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.sequences/sequence.html, https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines.flow/flow.html, https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines.channels/produce.html, etc.

I see. Didn't know they're called

flow

builders

only the

flow

one is a flow builder, the others are just builders in the same style

So, I'm guessing, there was a need to build (relatively large) immutable lists efficiently thats why this came about

Ok that YouTrack makes a lot more sense, thanks!