Hi maybe a stupid question but I never thought about that before. When I define a

mutableListOf<String>

and pass this to a consuming function, should I convert this list explicitly to

List<String>

with

toList()

to have this list immutable or is it enough to define the parameter as

List<String>

like:

fun consumingList(list: List<String>)

But then I'm asking if it's really an immutable list... I could still cast it to a mutable List again, not?

Defining the parameter like that is fine. It’s all mutable under the hood.

List

just exposes less than

MutableList

. And like you mentioned, you can use

toList()

or

toMutableList()

to convert between them

depends on how much you trust your consumers, it might be okay just to cast

ok, Thanks guys :)