with the introduction of a lot of

orNull

functions in mind, I was unpleasantly surprised there is no such thing as

List<T>.indexOfFirstOrNull

Looks like it’s in YouTrack but was closed on the basis that

null

isn’t really much more useful than

-1

. Personally, I’m with you; I would much prefer

null

. An unexpected

-1

can easily go unnoticed, leading to errors down the line. Whereas the type system forces you to handle

null

, so if there’s a chance my index won’t exist, I definitely want that. I suppose the downside of using

null

is that the return type would have to be boxed. But since we’re only dealing with a single value here, I don’t see that being a big concern.

how is 'null' not more usefull than''-1' 😛?

If the issue was just boxing, I'd instead like to see a value class wrapping around

Int

where you'd either clearly assert that you're getting a useful integer or have to write a case for when the item is not found, maybe

value class Index(private val i: Int)

.

you can write it as

list.indexOfFirst(foo).takeUnless { it == -1 }