Returns the size of the collection.

abstract val size: Int

Checks if the specified element is contained in this collection.

abstract fun contains(element: E): Boolean

Checks if all elements in the specified collection are contained in this collection.

abstract fun containsAll(elements: Collection<E>): Boolean

Returns true if the collection is empty (contains no elements), false otherwise.

abstract fun isEmpty(): Boolean

Returns an iterator over the elements of this object.

abstract fun iterator(): Iterator<E>

Returns an IntRange of the valid indices for this collection.

val Collection<*>.indices: IntRange

Returns true if all elements match the given predicate.

fun <T> Iterable<T>.all(predicate: (T) -> Boolean): Boolean

Returns true if collection has at least one element.

fun <T> Iterable<T>.any(): Boolean

Returns true if at least one element matches the given predicate.

fun <T> Iterable<T>.any(predicate: (T) -> Boolean): Boolean

Returns this collection as an Iterable.

fun <T> Iterable<T>.asIterable(): Iterable<T>

Creates a Sequence instance that wraps the original collection returning its elements when being iterated.

fun <T> Iterable<T>.asSequence(): Sequence<T>

Returns a Map containing key-value pairs provided by transform function applied to elements of the given collection.

fun <T, K, V> Iterable<T>.associate(
    transform: (T) -> Pair<K, V>
): Map<K, V>

Returns a Map containing the elements from the given collection indexed by the key returned from keySelector function applied to each element.

fun <T, K> Iterable<T>.associateBy(
    keySelector: (T) -> K
): Map<K, T>

Returns a Map containing the values provided by valueTransform and indexed by keySelector functions applied to elements of the given collection.

fun <T, K, V> Iterable<T>.associateBy(
    keySelector: (T) -> K, 
    valueTransform: (T) -> V
): Map<K, V>

Populates and returns the destination mutable map with key-value pairs, where key is provided by the keySelector function applied to each element of the given collection and value is the element itself.

fun <T, K, M : MutableMap<in K, in T>> Iterable<T>.associateByTo(
    destination: M, 
    keySelector: (T) -> K
): M

Populates and returns the destination mutable map with key-value pairs, where key is provided by the keySelector function and and value is provided by the valueTransform function applied to elements of the given collection.

fun <T, K, V, M : MutableMap<in K, in V>> Iterable<T>.associateByTo(
    destination: M, 
    keySelector: (T) -> K, 
    valueTransform: (T) -> V
): M

Populates and returns the destination mutable map with key-value pairs provided by transform function applied to each element of the given collection.

fun <T, K, V, M : MutableMap<in K, in V>> Iterable<T>.associateTo(
    destination: M, 
    transform: (T) -> Pair<K, V>
): M

Returns a Map where keys are elements from the given collection and values are produced by the valueSelector function applied to each element.

fun <K, V> Iterable<K>.associateWith(
    valueSelector: (K) -> V
): Map<K, V>

Populates and returns the destination mutable map with key-value pairs for each element of the given collection, where key is the element itself and value is provided by the valueSelector function applied to that key.

fun <K, V, M : MutableMap<in K, in V>> Iterable<K>.associateWithTo(
    destination: M, 
    valueSelector: (K) -> V
): M

Splits this collection into a list of lists each not exceeding the given size.

fun <T> Iterable<T>.chunked(size: Int): List<List<T>>

Splits this collection into several lists each not exceeding the given size and applies the given transform function to an each.

fun <T, R> Iterable<T>.chunked(
    size: Int, 
    transform: (List<T>) -> R
): List<R>

Returns true if element is found in the collection.

operator fun <T> Iterable<T>.contains(element: T): Boolean

Checks if all elements in the specified collection are contained in this collection.

fun <T> Collection<T>.containsAll(
    elements: Collection<T>
): Boolean

Returns the number of elements matching the given predicate.

fun <T> Iterable<T>.count(predicate: (T) -> Boolean): Int

Returns a list containing only distinct elements from the given collection.

fun <T> Iterable<T>.distinct(): List<T>

Returns a list containing only elements from the given collection having distinct keys returned by the given selector function.

fun <T, K> Iterable<T>.distinctBy(
    selector: (T) -> K
): List<T>

Returns a list containing all elements except first n elements.

fun <T> Iterable<T>.drop(n: Int): List<T>

Returns a list containing all elements except first elements that satisfy the given predicate.

fun <T> Iterable<T>.dropWhile(
    predicate: (T) -> Boolean
): List<T>

Returns an element at the given index or throws an IndexOutOfBoundsException if the index is out of bounds of this collection.

fun <T> Iterable<T>.elementAt(index: Int): T

Returns an element at the given index or the result of calling the defaultValue function if the index is out of bounds of this collection.

fun <T> Iterable<T>.elementAtOrElse(
    index: Int, 
    defaultValue: (Int) -> T
): T

Returns an element at the given index or null if the index is out of bounds of this collection.

fun <T> Iterable<T>.elementAtOrNull(index: Int): T?

Returns a list containing only elements matching the given predicate.

fun <T> Iterable<T>.filter(
    predicate: (T) -> Boolean
): List<T>

Returns a list containing only elements matching the given predicate.

fun <T> Iterable<T>.filterIndexed(
    predicate: (index: Int, T) -> Boolean
): List<T>

Appends all elements matching the given predicate to the given destination.

fun <T, C : MutableCollection<in T>> Iterable<T>.filterIndexedTo(
    destination: C, 
    predicate: (index: Int, T) -> Boolean
): C

Returns a list containing all elements that are instances of specified type parameter R.

fun <R> Iterable<*>.filterIsInstance(): List<R>

Returns a list containing all elements that are instances of specified class.

fun <R> Iterable<*>.filterIsInstance(
    klass: Class<R>
): List<R>

Appends all elements that are instances of specified type parameter R to the given destination.

fun <R, C : MutableCollection<in R>> Iterable<*>.filterIsInstanceTo(
    destination: C
): C

Appends all elements that are instances of specified class to the given destination.

fun <C : MutableCollection<in R>, R> Iterable<*>.filterIsInstanceTo(
    destination: C, 
    klass: Class<R>
): C

Returns a list containing all elements not matching the given predicate.

fun <T> Iterable<T>.filterNot(
    predicate: (T) -> Boolean
): List<T>

Returns a list containing all elements that are not null.

fun <T : Any> Iterable<T?>.filterNotNull(): List<T>

Appends all elements that are not null to the given destination.

fun <C : MutableCollection<in T>, T : Any> Iterable<T?>.filterNotNullTo(
    destination: C
): C

Appends all elements not matching the given predicate to the given destination.

fun <T, C : MutableCollection<in T>> Iterable<T>.filterNotTo(
    destination: C, 
    predicate: (T) -> Boolean
): C

Appends all elements matching the given predicate to the given destination.

fun <T, C : MutableCollection<in T>> Iterable<T>.filterTo(
    destination: C, 
    predicate: (T) -> Boolean
): C

Returns the first element matching the given predicate, or null if no such element was found.

fun <T> Iterable<T>.find(predicate: (T) -> Boolean): T?

Returns the last element matching the given predicate, or null if no such element was found.

fun <T> Iterable<T>.findLast(predicate: (T) -> Boolean): T?

Returns first element.

fun <T> Iterable<T>.first(): T

Returns the first element matching the given predicate.

fun <T> Iterable<T>.first(predicate: (T) -> Boolean): T

Returns the first element, or null if the collection is empty.

fun <T> Iterable<T>.firstOrNull(): T?

Returns the first element matching the given predicate, or null if element was not found.

fun <T> Iterable<T>.firstOrNull(
    predicate: (T) -> Boolean
): T?

Returns a single list of all elements yielded from results of transform function being invoked on each element of original collection.

fun <T, R> Iterable<T>.flatMap(
    transform: (T) -> Iterable<R>
): List<R>

fun <T, R> Iterable<T>.flatMap(
    transform: (T) -> Sequence<R>
): List<R>

Returns a single list of all elements yielded from results of transform function being invoked on each element and its index in the original collection.

fun <T, R> Iterable<T>.flatMapIndexed(
    transform: (index: Int, T) -> Iterable<R>
): List<R>

fun <T, R> Iterable<T>.flatMapIndexed(
    transform: (index: Int, T) -> Sequence<R>
): List<R>

Appends all elements yielded from results of transform function being invoked on each element and its index in the original collection, to the given destination.

fun <T, R, C : MutableCollection<in R>> Iterable<T>.flatMapIndexedTo(
    destination: C, 
    transform: (index: Int, T) -> Iterable<R>
): C

fun <T, R, C : MutableCollection<in R>> Iterable<T>.flatMapIndexedTo(
    destination: C, 
    transform: (index: Int, T) -> Sequence<R>
): C

Appends all elements yielded from results of transform function being invoked on each element of original collection, to the given destination.

fun <T, R, C : MutableCollection<in R>> Iterable<T>.flatMapTo(
    destination: C, 
    transform: (T) -> Iterable<R>
): C

fun <T, R, C : MutableCollection<in R>> Iterable<T>.flatMapTo(
    destination: C, 
    transform: (T) -> Sequence<R>
): C

Returns a single list of all elements from all collections in the given collection.

fun <T> Iterable<Iterable<T>>.flatten(): List<T>

Accumulates value starting with initial value and applying operation from left to right to current accumulator value and each element.

fun <T, R> Iterable<T>.fold(
    initial: R, 
    operation: (acc: R, T) -> R
): R

Accumulates value starting with initial value and applying operation from left to right to current accumulator value and each element with its index in the original collection.

fun <T, R> Iterable<T>.foldIndexed(
    initial: R, 
    operation: (index: Int, acc: R, T) -> R
): R

Performs the given action on each element.

fun <T> Iterable<T>.forEach(action: (T) -> Unit)

Performs the given action on each element, providing sequential index with the element.

fun <T> Iterable<T>.forEachIndexed(
    action: (index: Int, T) -> Unit)

Groups elements of the original collection by the key returned by the given keySelector function applied to each element and returns a map where each group key is associated with a list of corresponding elements.

fun <T, K> Iterable<T>.groupBy(
    keySelector: (T) -> K
): Map<K, List<T>>

Groups values returned by the valueTransform function applied to each element of the original collection by the key returned by the given keySelector function applied to the element and returns a map where each group key is associated with a list of corresponding values.

fun <T, K, V> Iterable<T>.groupBy(
    keySelector: (T) -> K, 
    valueTransform: (T) -> V
): Map<K, List<V>>

Groups elements of the original collection by the key returned by the given keySelector function applied to each element and puts to the destination map each group key associated with a list of corresponding elements.

fun <T, K, M : MutableMap<in K, MutableList<T>>> Iterable<T>.groupByTo(
    destination: M, 
    keySelector: (T) -> K
): M

Groups values returned by the valueTransform function applied to each element of the original collection by the key returned by the given keySelector function applied to the element and puts to the destination map each group key associated with a list of corresponding values.

fun <T, K, V, M : MutableMap<in K, MutableList<V>>> Iterable<T>.groupByTo(
    destination: M, 
    keySelector: (T) -> K, 
    valueTransform: (T) -> V
): M

Creates a Grouping source from a collection to be used later with one of group-and-fold operations using the specified keySelector function to extract a key from each element.

fun <T, K> Iterable<T>.groupingBy(
    keySelector: (T) -> K
): Grouping<T, K>

Returns this array if it's not empty or the result of calling defaultValue function if the array is empty.

fun <C, R> C.ifEmpty(
    defaultValue: () -> R
): R where C : Array<*>, C : R

Returns first index of element, or -1 if the collection does not contain element.

fun <T> Iterable<T>.indexOf(element: T): Int

Returns index of the first element matching the given predicate, or -1 if the collection does not contain such element.

fun <T> Iterable<T>.indexOfFirst(
    predicate: (T) -> Boolean
): Int

Returns index of the last element matching the given predicate, or -1 if the collection does not contain such element.

fun <T> Iterable<T>.indexOfLast(
    predicate: (T) -> Boolean
): Int

Returns a set containing all elements that are contained by both this collection and the specified collection.

infix fun <T> Iterable<T>.intersect(
    other: Iterable<T>
): Set<T>

Returns true if the collection is not empty.

fun <T> Collection<T>.isNotEmpty(): Boolean

Returns true if this nullable collection is either null or empty.

fun <T> Collection<T>?.isNullOrEmpty(): Boolean

Appends the string from all the elements separated using separator and using the given prefix and postfix if supplied.

fun <T, A : Appendable> Iterable<T>.joinTo(
    buffer: A, 
    separator: CharSequence = ", ", 
    prefix: CharSequence = "", 
    postfix: CharSequence = "", 
    limit: Int = -1, 
    truncated: CharSequence = "...", 
    transform: ((T) -> CharSequence)? = null
): A

Creates a string from all the elements separated using separator and using the given prefix and postfix if supplied.

fun <T> Iterable<T>.joinToString(
    separator: CharSequence = ", ", 
    prefix: CharSequence = "", 
    postfix: CharSequence = "", 
    limit: Int = -1, 
    truncated: CharSequence = "...", 
    transform: ((T) -> CharSequence)? = null
): String

Returns the last element.

fun <T> Iterable<T>.last(): T

Returns the last element matching the given predicate.

fun <T> Iterable<T>.last(predicate: (T) -> Boolean): T

Returns last index of element, or -1 if the collection does not contain element.

fun <T> Iterable<T>.lastIndexOf(element: T): Int

Returns the last element, or null if the collection is empty.

fun <T> Iterable<T>.lastOrNull(): T?

Returns the last element matching the given predicate, or null if no such element was found.

fun <T> Iterable<T>.lastOrNull(predicate: (T) -> Boolean): T?

Returns a list containing the results of applying the given transform function to each element in the original collection.

fun <T, R> Iterable<T>.map(transform: (T) -> R): List<R>

Returns a list containing the results of applying the given transform function to each element and its index in the original collection.

fun <T, R> Iterable<T>.mapIndexed(
    transform: (index: Int, T) -> R
): List<R>

Returns a list containing only the non-null results of applying the given transform function to each element and its index in the original collection.

fun <T, R : Any> Iterable<T>.mapIndexedNotNull(
    transform: (index: Int, T) -> R?
): List<R>

Applies the given transform function to each element and its index in the original collection and appends only the non-null results to the given destination.

fun <T, R : Any, C : MutableCollection<in R>> Iterable<T>.mapIndexedNotNullTo(
    destination: C, 
    transform: (index: Int, T) -> R?
): C

Applies the given transform function to each element and its index in the original collection and appends the results to the given destination.

fun <T, R, C : MutableCollection<in R>> Iterable<T>.mapIndexedTo(
    destination: C, 
    transform: (index: Int, T) -> R
): C

Returns a list containing only the non-null results of applying the given transform function to each element in the original collection.

fun <T, R : Any> Iterable<T>.mapNotNull(
    transform: (T) -> R?
): List<R>

Applies the given transform function to each element in the original collection and appends only the non-null results to the given destination.

fun <T, R : Any, C : MutableCollection<in R>> Iterable<T>.mapNotNullTo(
    destination: C, 
    transform: (T) -> R?
): C

Applies the given transform function to each element of the original collection and appends the results to the given destination.

fun <T, R, C : MutableCollection<in R>> Iterable<T>.mapTo(
    destination: C, 
    transform: (T) -> R
): C

Returns the first element yielding the largest value of the given function or null if there are no elements.

fun <T, R : Comparable<R>> Iterable<T>.maxByOrNull(
    selector: (T) -> R
): T?

Returns the largest value among all values produced by selector function applied to each element in the collection.

fun <T> Iterable<T>.maxOf(selector: (T) -> Double): Double

fun <T> Iterable<T>.maxOf(selector: (T) -> Float): Float

fun <T, R : Comparable<R>> Iterable<T>.maxOf(
    selector: (T) -> R
): R

Returns the largest value among all values produced by selector function applied to each element in the collection or null if there are no elements.

fun <T> Iterable<T>.maxOfOrNull(
    selector: (T) -> Double
): Double?

fun <T> Iterable<T>.maxOfOrNull(
    selector: (T) -> Float
): Float?

fun <T, R : Comparable<R>> Iterable<T>.maxOfOrNull(
    selector: (T) -> R
): R?

Returns the largest value according to the provided comparator among all values produced by selector function applied to each element in the collection.

fun <T, R> Iterable<T>.maxOfWith(
    comparator: Comparator<in R>, 
    selector: (T) -> R
): R

Returns the largest value according to the provided comparator among all values produced by selector function applied to each element in the collection or null if there are no elements.

fun <T, R> Iterable<T>.maxOfWithOrNull(
    comparator: Comparator<in R>, 
    selector: (T) -> R
): R?

Returns the first element having the largest value according to the provided comparator or null if there are no elements.

fun <T> Iterable<T>.maxWithOrNull(
    comparator: Comparator<in T>
): T?

Returns the first element yielding the smallest value of the given function or null if there are no elements.

fun <T, R : Comparable<R>> Iterable<T>.minByOrNull(
    selector: (T) -> R
): T?

Returns the smallest value among all values produced by selector function applied to each element in the collection.

fun <T> Iterable<T>.minOf(selector: (T) -> Double): Double

fun <T> Iterable<T>.minOf(selector: (T) -> Float): Float

fun <T, R : Comparable<R>> Iterable<T>.minOf(
    selector: (T) -> R
): R

Returns the smallest value among all values produced by selector function applied to each element in the collection or null if there are no elements.

fun <T> Iterable<T>.minOfOrNull(
    selector: (T) -> Double
): Double?

fun <T> Iterable<T>.minOfOrNull(
    selector: (T) -> Float
): Float?

fun <T, R : Comparable<R>> Iterable<T>.minOfOrNull(
    selector: (T) -> R
): R?

Returns the smallest value according to the provided comparator among all values produced by selector function applied to each element in the collection.

fun <T, R> Iterable<T>.minOfWith(
    comparator: Comparator<in R>, 
    selector: (T) -> R
): R

Returns the smallest value according to the provided comparator among all values produced by selector function applied to each element in the collection or null if there are no elements.

fun <T, R> Iterable<T>.minOfWithOrNull(
    comparator: Comparator<in R>, 
    selector: (T) -> R
): R?

Returns a set containing all elements of the original set except the given element.

operator fun <T> Set<T>.minus(element: T): Set<T>

Returns a set containing all elements of the original set except the elements contained in the given elements array.

operator fun <T> Set<T>.minus(elements: Array<out T>): Set<T>

Returns a set containing all elements of the original set except the elements contained in the given elements collection.

operator fun <T> Set<T>.minus(elements: Iterable<T>): Set<T>

Returns a set containing all elements of the original set except the elements contained in the given elements sequence.

operator fun <T> Set<T>.minus(elements: Sequence<T>): Set<T>

Returns a list containing all elements of the original collection without the first occurrence of the given element.

operator fun <T> Iterable<T>.minus(element: T): List<T>

Returns a list containing all elements of the original collection except the elements contained in the given elements array.

operator fun <T> Iterable<T>.minus(
    elements: Array<out T>
): List<T>

Returns a list containing all elements of the original collection except the elements contained in the given elements collection.

operator fun <T> Iterable<T>.minus(
    elements: Iterable<T>
): List<T>

Returns a list containing all elements of the original collection except the elements contained in the given elements sequence.

operator fun <T> Iterable<T>.minus(
    elements: Sequence<T>
): List<T>

Returns a set containing all elements of the original set except the given element.

fun <T> Set<T>.minusElement(element: T): Set<T>

Returns a list containing all elements of the original collection without the first occurrence of the given element.

fun <T> Iterable<T>.minusElement(element: T): List<T>

Returns the first element having the smallest value according to the provided comparator or null if there are no elements.

fun <T> Iterable<T>.minWithOrNull(
    comparator: Comparator<in T>
): T?

Returns true if the collection has no elements.

fun <T> Iterable<T>.none(): Boolean

Returns true if no elements match the given predicate.

fun <T> Iterable<T>.none(predicate: (T) -> Boolean): Boolean

Performs the given action on each element and returns the collection itself afterwards.

fun <T, C : Iterable<T>> C.onEach(action: (T) -> Unit): C

Performs the given action on each element, providing sequential index with the element, and returns the collection itself afterwards.

fun <T, C : Iterable<T>> C.onEachIndexed(
    action: (index: Int, T) -> Unit
): C

Returns this Set if it's not null and the empty set otherwise.

fun <T> Set<T>?.orEmpty(): Set<T>

Splits the original collection into pair of lists, where first list contains elements for which predicate yielded true, while second list contains elements for which predicate yielded false.

fun <T> Iterable<T>.partition(
    predicate: (T) -> Boolean
): Pair<List<T>, List<T>>

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 <T> Set<T>.plus(element: T): Set<T>

Returns a set containing all elements of the original set and the given elements array, which aren't already in this set.

operator fun <T> Set<T>.plus(elements: Array<out T>): Set<T>

Returns a set containing all elements of the original set and the given elements collection, which aren't already in this set. The returned set preserves the element iteration order of the original set.

operator fun <T> Set<T>.plus(elements: Iterable<T>): Set<T>

Returns a set containing all elements of the original set and the given elements sequence, which aren't already in this set.

operator fun <T> Set<T>.plus(elements: Sequence<T>): Set<T>

Returns a list containing all elements of the original collection and then the given element.

operator fun <T> Iterable<T>.plus(element: T): List<T>

operator fun <T> Collection<T>.plus(element: T): List<T>

Returns a list containing all elements of the original collection and then all elements of the given elements array.

operator fun <T> Iterable<T>.plus(
    elements: Array<out T>
): List<T>

operator fun <T> Collection<T>.plus(
    elements: Array<out T>
): List<T>

Returns a list containing all elements of the original collection and then all elements of the given elements collection.

operator fun <T> Iterable<T>.plus(
    elements: Iterable<T>
): List<T>

operator fun <T> Collection<T>.plus(
    elements: Iterable<T>
): List<T>

Returns a list containing all elements of the original collection and then all elements of the given elements sequence.

operator fun <T> Iterable<T>.plus(
    elements: Sequence<T>
): List<T>

operator fun <T> Collection<T>.plus(
    elements: Sequence<T>
): List<T>

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

fun <T> Set<T>.plusElement(element: T): Set<T>

Returns a list containing all elements of the original collection and then the given element.

fun <T> Iterable<T>.plusElement(element: T): List<T>

fun <T> Collection<T>.plusElement(element: T): List<T>

Returns a random element from this collection.

fun <T> Collection<T>.random(): T

Returns a random element from this collection using the specified source of randomness.

fun <T> Collection<T>.random(random: Random): T

Returns a random element from this collection, or null if this collection is empty.

fun <T> Collection<T>.randomOrNull(): T?

Returns a random element from this collection using the specified source of randomness, or null if this collection is empty.

fun <T> Collection<T>.randomOrNull(random: Random): T?

Accumulates value starting with the first element and applying operation from left to right to current accumulator value and each element.

fun <S, T : S> Iterable<T>.reduce(
    operation: (acc: S, T) -> S
): S

Accumulates value starting with the first element and applying operation from left to right to current accumulator value and each element with its index in the original collection.

fun <S, T : S> Iterable<T>.reduceIndexed(
    operation: (index: Int, acc: S, T) -> S
): S

Accumulates value starting with the first element and applying operation from left to right to current accumulator value and each element with its index in the original collection.

fun <S, T : S> Iterable<T>.reduceIndexedOrNull(
    operation: (index: Int, acc: S, T) -> S
): S?

Accumulates value starting with the first element and applying operation from left to right to current accumulator value and each element.

fun <S, T : S> Iterable<T>.reduceOrNull(
    operation: (acc: S, T) -> S
): S?

Returns an original collection containing all the non-null elements, throwing an IllegalArgumentException if there are any null elements.

fun <T : Any> Iterable<T?>.requireNoNulls(): Iterable<T>

Returns a list with elements in reversed order.

fun <T> Iterable<T>.reversed(): List<T>

Returns a list containing successive accumulation values generated by applying operation from left to right to each element and current accumulator value that starts with initial value.

fun <T, R> Iterable<T>.runningFold(
    initial: R, 
    operation: (acc: R, T) -> R
): List<R>

Returns a list containing successive accumulation values generated by applying operation from left to right to each element, its index in the original collection and current accumulator value that starts with initial value.

fun <T, R> Iterable<T>.runningFoldIndexed(
    initial: R, 
    operation: (index: Int, acc: R, T) -> R
): List<R>

Returns a list containing successive accumulation values generated by applying operation from left to right to each element and current accumulator value that starts with the first element of this collection.

fun <S, T : S> Iterable<T>.runningReduce(
    operation: (acc: S, T) -> S
): List<S>

Returns a list containing successive accumulation values generated by applying operation from left to right to each element, its index in the original collection and current accumulator value that starts with the first element of this collection.

fun <S, T : S> Iterable<T>.runningReduceIndexed(
    operation: (index: Int, acc: S, T) -> S
): List<S>

Returns a list containing successive accumulation values generated by applying operation from left to right to each element and current accumulator value that starts with initial value.

fun <T, R> Iterable<T>.scan(
    initial: R, 
    operation: (acc: R, T) -> R
): List<R>

Returns a list containing successive accumulation values generated by applying operation from left to right to each element, its index in the original collection and current accumulator value that starts with initial value.

fun <T, R> Iterable<T>.scanIndexed(
    initial: R, 
    operation: (index: Int, acc: R, T) -> R
): List<R>

Returns a new list with the elements of this list randomly shuffled using the specified random instance as the source of randomness.

fun <T> Iterable<T>.shuffled(random: Random): List<T>

fun <T> Iterable<T>.shuffled(random: Random): List<T>

Returns the single element, or throws an exception if the collection is empty or has more than one element.

fun <T> Iterable<T>.single(): T

Returns the single element matching the given predicate, or throws exception if there is no or more than one matching element.

fun <T> Iterable<T>.single(predicate: (T) -> Boolean): T

Returns single element, or null if the collection is empty or has more than one element.

fun <T> Iterable<T>.singleOrNull(): T?

Returns the single element matching the given predicate, or null if element was not found or more than one element was found.

fun <T> Iterable<T>.singleOrNull(
    predicate: (T) -> Boolean
): T?

Returns a list of all elements sorted according to natural sort order of the value returned by specified selector function.

fun <T, R : Comparable<R>> Iterable<T>.sortedBy(
    selector: (T) -> R?
): List<T>

Returns a list of all elements sorted descending according to natural sort order of the value returned by specified selector function.

fun <T, R : Comparable<R>> Iterable<T>.sortedByDescending(
    selector: (T) -> R?
): List<T>

Returns a list of all elements sorted according to the specified comparator.

fun <T> Iterable<T>.sortedWith(
    comparator: Comparator<in T>
): List<T>

Returns a set containing all elements that are contained by this collection and not contained by the specified collection.

infix fun <T> Iterable<T>.subtract(
    other: Iterable<T>
): Set<T>

Returns the sum of all values produced by selector function applied to each element in the collection.

fun <T> Iterable<T>.sumBy(selector: (T) -> Int): Int

Returns the sum of all values produced by selector function applied to each element in the collection.

fun <T> Iterable<T>.sumByDouble(
    selector: (T) -> Double
): Double

Returns the sum of all values produced by selector function applied to each element in the collection.

fun <T> Iterable<T>.sumOf(selector: (T) -> Double): Double

fun <T> Iterable<T>.sumOf(selector: (T) -> Int): Int

fun <T> Iterable<T>.sumOf(selector: (T) -> Long): Long

fun <T> Iterable<T>.sumOf(selector: (T) -> UInt): UInt

fun <T> Iterable<T>.sumOf(selector: (T) -> ULong): ULong

fun <T> Iterable<T>.sumOf(
    selector: (T) -> BigDecimal
): BigDecimal

fun <T> Iterable<T>.sumOf(
    selector: (T) -> BigInteger
): BigInteger

Returns a list containing first n elements.

fun <T> Iterable<T>.take(n: Int): List<T>

Returns a list containing first elements satisfying the given predicate.

fun <T> Iterable<T>.takeWhile(
    predicate: (T) -> Boolean
): List<T>

Returns an array of Boolean containing all of the elements of this collection.

fun Collection<Boolean>.toBooleanArray(): BooleanArray

Returns an array of Byte containing all of the elements of this collection.

fun Collection<Byte>.toByteArray(): ByteArray

Returns an array of Char containing all of the elements of this collection.

fun Collection<Char>.toCharArray(): CharArray

Appends all elements to the given destination collection.

fun <T, C : MutableCollection<in T>> Iterable<T>.toCollection(
    destination: C
): C

Returns an array of Double containing all of the elements of this collection.

fun Collection<Double>.toDoubleArray(): DoubleArray

Returns an array of Float containing all of the elements of this collection.

fun Collection<Float>.toFloatArray(): FloatArray

Returns a new HashSet of all elements.

fun <T> Iterable<T>.toHashSet(): HashSet<T>

Returns an array of Int containing all of the elements of this collection.

fun Collection<Int>.toIntArray(): IntArray

Returns a List containing all elements.

fun <T> Iterable<T>.toList(): List<T>

Returns an array of Long containing all of the elements of this collection.

fun Collection<Long>.toLongArray(): LongArray

Returns a new map containing all key-value pairs from the given collection of pairs.

fun <K, V> Iterable<Pair<K, V>>.toMap(): Map<K, V>

Populates and returns the destination mutable map with key-value pairs from the given collection of pairs.

fun <K, V, M : MutableMap<in K, in V>> Iterable<Pair<K, V>>.toMap(
    destination: M
): M

Returns a new MutableSet containing all distinct elements from the given collection.

fun <T> Iterable<T>.toMutableSet(): MutableSet<T>

Returns a Set of all elements.

fun <T> Iterable<T>.toSet(): Set<T>

Returns an array of Short containing all of the elements of this collection.

fun Collection<Short>.toShortArray(): ShortArray

Returns a new SortedSet of all elements.

fun <T> Iterable<T>.toSortedSet(
    comparator: Comparator<in T>
): SortedSet<T>

Returns an array of UByte containing all of the elements of this collection.

fun Collection<UByte>.toUByteArray(): UByteArray

Returns an array of UInt containing all of the elements of this collection.

fun Collection<UInt>.toUIntArray(): UIntArray

Returns an array of ULong containing all of the elements of this collection.

fun Collection<ULong>.toULongArray(): ULongArray

Returns an array of UShort containing all of the elements of this collection.

fun Collection<UShort>.toUShortArray(): UShortArray

Returns a set containing all distinct elements from both collections.

infix fun <T> Iterable<T>.union(other: Iterable<T>): Set<T>

Returns a pair of lists, where first list is built from the first values of each pair from this collection, second list is built from the second values of each pair from this collection.

fun <T, R> Iterable<Pair<T, R>>.unzip(): Pair<List<T>, List<R>>

Returns a list of snapshots of the window of the given size sliding along this collection with the given step, where each snapshot is a list.

fun <T> Iterable<T>.windowed(
    size: Int, 
    step: Int = 1, 
    partialWindows: Boolean = false
): List<List<T>>

Returns a list of results of applying the given transform function to an each list representing a view over the window of the given size sliding along this collection with the given step.

fun <T, R> Iterable<T>.windowed(
    size: Int, 
    step: Int = 1, 
    partialWindows: Boolean = false, 
    transform: (List<T>) -> R
): List<R>

Returns a lazy Iterable that wraps each element of the original collection into an IndexedValue containing the index of that element and the element itself.

fun <T> Iterable<T>.withIndex(): Iterable<IndexedValue<T>>

Returns a list of pairs built from the elements of this collection and the other array with the same index. The returned list has length of the shortest collection.

infix fun <T, R> Iterable<T>.zip(
    other: Array<out R>
): List<Pair<T, R>>

Returns a list of values built from the elements of this collection and the other array with the same index using the provided transform function applied to each pair of elements. The returned list has length of the shortest collection.

fun <T, R, V> Iterable<T>.zip(
    other: Array<out R>, 
    transform: (a: T, b: R) -> V
): List<V>

Returns a list of pairs built from the elements of this collection and other collection with the same index. The returned list has length of the shortest collection.

infix fun <T, R> Iterable<T>.zip(
    other: Iterable<R>
): List<Pair<T, R>>

Returns a list of values built from the elements of this collection and the other collection with the same index using the provided transform function applied to each pair of elements. The returned list has length of the shortest collection.

fun <T, R, V> Iterable<T>.zip(
    other: Iterable<R>, 
    transform: (a: T, b: R) -> V
): List<V>

Returns a list of pairs of each two adjacent elements in this collection.

fun <T> Iterable<T>.zipWithNext(): List<Pair<T, T>>

Returns a list containing the results of applying the given transform function to an each pair of two adjacent elements in this collection.

fun <T, R> Iterable<T>.zipWithNext(
    transform: (a: T, b: T) -> R
): List<R>

Provides a skeletal implementation of the read-only Set interface.

abstract class AbstractSet<out E> : 
    AbstractCollection<E>, 
    Set<E>

A generic unordered collection of elements that does not support duplicate elements, and supports adding and removing elements.

interface MutableSet<E> : Set<E>, MutableCollection<E>