You could do something like this:

val list = listOf("hello" to "world", "hello" to "world2", "bla" to "quz")
val result = list.groupingBy { it.first }.fold(null as String?) { acc, elem -> acc ?: elem.second }

looks good, thanks! I was thinking also using just

map

- similar to what you did with

aggregate

The nice thing about using

groupingBy

is that it does not construct and intermediary

Map<K, List<V>>

for the grouping.

okay...

You can of course use

groupingBy

like I showed in your extension function 😉

I thought about that, thanks!