why doesnt `List` inherit from `Set` ? isn't a Set...

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[LastExceed]

why doesnt List inherit from Set ? isn't a Set the same thing as a List but without indexing?

[tddmonkey]

No - a set cannot have duplicates, a list can

[Emil Kantis]

A set can't contain duplicates, so no

[LastExceed]

oh i didn't know that. thanks

[louiscad]

Both are from the Collection type though.

[corneil]

List is usually ordered where as a Set is generally not ordered unless you use one that is specifically ordered like a TreeSet where the items are retrieved in sorted order.

[Mike]

Lists in Java/Kotlin/general are not sorted/ordered. Items are retrieved in the order they are inserted (assuming using the iterator). Sorting is 'on request' only.

[corneil]

My mistake in confusing ordering and sorted in this case. List will generally maintain inserted order. Set will not.

[tddmonkey]

being pedantic - retrieved in the order they are inserted is ordered

[LastExceed]

i am aware of the odering stuff. i was just wondering why i can't abstract a list to a set (and the order would be just another information that gets lost with that abstraction) but sets not being able to hold duplicates already answered it

[Mike]

@tddmonkey Very true. Sorted != ordered. So in summary Lists are not sorted, but are ordered. Sets are neither sorted, nor ordered. So in this case, I wouldn't consider it pedantic 😉

[tddmonkey]

I don’t mind being pedantic 😄

[gildor]

Kotlin default implementation is LinkedHashSet (used by buildSet, setOf, mutableSetOf, so it ordered by default

[LastExceed]

thats an implementation detail that could change any time

[tddmonkey]

If you want insertion order guarantees you should be explicit about the type you use