On the following documentation page for “Set” collection:

https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/-set/index.html

there are definitions for functions `plus`

and `plusElement`

which have identical descriptions. But the results of those functions are not identical.

`plusElement`

definition:

Returns a set containing all elements of the original set and then the given element if it isn’t already in this set.

fun Set.plusElement(element: T): Set

`plus`

definition:

Returns a set containing all elements of the original set and then the given element if it isn’t already in this set.

operator fun Set.plus(element: T): Set

`plusElement`

result (in Kotlin REPL)

setOf(‘a’…‘z’, ‘A’…‘Z’).plusElement(‘0’…‘9’)

res3: kotlin.collections.Set<kotlin.ranges.CharRange> = [a…z, A…Z, 0…9]

`plus`

result:

setOf(‘a’…‘z’, ‘A’…‘Z’).plus(‘0’…‘9’)

res4: kotlin.collections.Set<kotlin.Any> = [a…z, A…Z, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

Is this difference in behavior intended?