Can you list the main data structures used in Kotlin and describe them?

In Kotlin, the main data structures are represented as collections and arrays. Here are the main ones:

• List — an ordered set of elements. It can be mutable (MutableList) or immutable (List). It allows duplicates and access by index.

• Set — a collection of unique elements without a specific order. It can also be mutable (MutableSet) or immutable (Set).

• Map — a collection of key-value pairs. Keys are unique. There are mutable (MutableMap) and immutable (Map) options.

• Array — a fixed-size array of elements of the same type. In Kotlin, arrays are represented by the class Array<T>.

• Sequence — lazy collections that are computed as needed, useful for large or infinite data streams.

Example usage:

val list: List<Int> = listOf(1, 2, 3)
val mutableList: MutableList<String> = mutableListOf("a", "b")
val set: Set<Int> = setOf(1, 2, 2, 3) // contains 1, 2, 3
val map: Map<String, Int> = mapOf("one" to 1, "two" to 2)
val array: Array<Int> = arrayOf(1, 2, 3)

// Sequence example
val seq = sequenceOf(1, 2, 3).map { it * 2 }
for (num in seq) {
    println(num)
}

These data structures cover most tasks related to storing and processing collections in Kotlin.