The Kotlin collections package contains extension functions for popular operations on sets: finding intersections, merging, or subtracting collections from each other.
To merge two collections into one, use the
union() function. It can be used in the infix form
a union b. Note that for ordered collections the order of the operands is important: in the resulting collection, the elements of the first operand go before the elements of the second.
To find an intersection between two collections (elements present in both of them), use
intersect(). To find collection elements not present in another collection, use
subtract(). Both these functions can be called in the infix form as well, for example,
a intersect b.
You can also apply
List. However, their result is always a
Set, even on lists. In this result, all the duplicate elements are merged into one and the index access is not available.