fun <T> Sequence<T>.distinct(): Sequence<T>

Returns a sequence containing only distinct elements from the given sequence.

Among equal elements of the given sequence, only the first one will be present in the resulting sequence. The elements in the resulting sequence are in the same order as they were in the source sequence.

The operation is intermediate and stateful.

import kotlin.test.*

fun main(args: Array<String>) {
//sampleStart
val list = listOf('a', 'A', 'b', 'B', 'A', 'a')
println(list.distinct()) // [a, A, b, B]
println(list.distinctBy { it.toUpperCase() }) // [a, b]
//sampleEnd
}