Type Parameters:

T - the type of elements contained in this Traversable

All Superinterfaces:

Foldable<T>, java.lang.Iterable<T>, Value<T>

All Known Subinterfaces:

BitSet<T>, IndexedSeq<T>, Iterator<T>, LinearSeq<T>, List<T>, Map<K,V>, Multimap<K,V>, Seq<T>, Set<T>, SortedMap<K,V>, SortedMultimap<K,V>, SortedSet<T>, Stream<T>, Tree<T>

All Known Implementing Classes:

AbstractIterator, AbstractMultimap, AbstractQueue, Array, BitSetModule.AbstractBitSet, BitSetModule.BitSet1, BitSetModule.BitSet2, BitSetModule.BitSetIterator, BitSetModule.BitSetN, CharSeq, HashArrayMappedTrieModule.LeafNodeIterator, HashMap, HashMultimap, HashSet, IteratorModule.CachedIterator, IteratorModule.ConcatIterator, IteratorModule.DistinctIterator, IteratorModule.EmptyIterator, IteratorModule.GroupedIterator, LinkedHashMap, LinkedHashMultimap, LinkedHashSet, List.Cons, List.Nil, PriorityQueue, Queue, Stream.Cons, Stream.Empty, StreamModule.AppendElements, StreamModule.ConsImpl, StreamModule.FlatMapIterator, StreamModule.StreamIterator, Tree.Empty, Tree.Node, TreeMap, TreeMultimap, TreeSet, Vector
```
public interface Traversable<T>
extends Foldable<T>, Value<T>
```
Represents a recursive, multi-valued data structure whose elements can be traversed in order. The iteration order is determined by Iterable.iterator() and may vary across calls.
This interface provides operations for:
- Basic access: querying elements, length, head/tail, and emptiness.
- Iteration: indexed traversal, sliding windows, and grouping.
- Numeric computations: sum, product, min/max, and averages.
- Reduction and folding: folding, reducing, and string representation.
- Selection and slicing: take/drop, filtering, partitioning, and sub-sequencing.
- Testing: uniqueness, order, distinctness, and sequence properties.
- Transformation: mapping, flat-mapping, scanning, zipping, and deduplication.
Implementations may be lazy or strict and may support infinite sequences.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method	Description
`default <K> Option<Map<K,T>>`	`arrangeBy(@NonNull java.util.function.Function<? super T,? extends K> getKey)`	Groups elements by a unique key extracted from each element.
`default Option<java.lang.Double>`	`average()`	Computes the average of the elements, assuming they are of type `Number`.
`<R> Traversable<R>`	`collect(@NonNull PartialFunction<? super T,? extends R> partialFunction)`	Applies a `PartialFunction` to all elements that are defined for it and collects the results.
`default boolean`	`containsAll(@NonNull java.lang.Iterable<? extends T> elements)`	Checks whether this `Traversable` contains all elements from the given iterable.
`default int`	`count(@NonNull java.util.function.Predicate<? super T> predicate)`	Counts the number of elements that satisfy the given predicate.
`Traversable<T>`	`distinct()`	Returns a new `Traversable` containing the elements of this instance with all duplicates removed.
`Traversable<T>`	`distinctBy(@NonNull java.util.Comparator<? super T> comparator)`	Returns a new `Traversable` containing the elements of this instance without duplicates, as determined by the given `comparator`.
`<U> Traversable<T>`	`distinctBy(@NonNull java.util.function.Function<? super T,? extends U> keyExtractor)`	Returns a new `Traversable` containing the elements of this instance without duplicates, based on keys extracted from elements using `keyExtractor`.
`Traversable<T>`	`drop(int n)`	Returns a new `Traversable` without the first `n` elements, or an empty instance if this contains fewer than `n` elements.
`Traversable<T>`	`dropRight(int n)`	Returns a new `Traversable` without the last `n` elements, or an empty instance if this contains fewer than `n` elements.
`Traversable<T>`	`dropUntil(@NonNull java.util.function.Predicate<? super T> predicate)`	Returns a new `Traversable` starting from the first element that satisfies the given `predicate`, dropping all preceding elements.
`Traversable<T>`	`dropWhile(@NonNull java.util.function.Predicate<? super T> predicate)`	Returns a new `Traversable` starting from the first element that does not satisfy the given `predicate`, dropping all preceding elements.
`boolean`	`equals(java.lang.Object obj)`	Determines whether this collection is equal to the given object.
`default boolean`	`existsUnique(@NonNull java.util.function.Predicate<? super T> predicate)`	Checks whether there is exactly one element in this traversable for which the given predicate holds.
`Traversable<T>`	`filter(@NonNull java.util.function.Predicate<? super T> predicate)`	Returns a new traversable containing only the elements that satisfy the given predicate.
`default Option<T>`	`find(@NonNull java.util.function.Predicate<? super T> predicate)`	Returns the first element that satisfies the given predicate.
`default Option<T>`	`findLast(@NonNull java.util.function.Predicate<? super T> predicate)`	Returns the last element that satisfies the given predicate.
`<U> Traversable<U>`	`flatMap(@NonNull java.util.function.Function<? super T,? extends java.lang.Iterable<? extends U>> mapper)`	Transforms each element of this Traversable into an `Iterable` of elements and flattens the resulting iterables into a single Traversable.
`default <U> U`	`foldLeft(U zero, @NonNull java.util.function.BiFunction<? super U,? super T,? extends U> f)`	Folds the elements of this structure from the left, starting with the given `zero` value and successively applying the `combine` function to each element.
`<U> U`	`foldRight(U zero, @NonNull java.util.function.BiFunction<? super T,? super U,? extends U> f)`	Folds the elements of this structure from the right, starting with the given `zero` value and successively applying the `combine` function to each element.
`default void`	`forEachWithIndex(@NonNull java.util.function.ObjIntConsumer<? super T> action)`	Performs the given action on each element of this Traversable along with its index.
`default T`	`get()`	Returns the first element of this `Traversable` in iteration order.
`<C> Map<C,? extends Traversable<T>>`	`groupBy(@NonNull java.util.function.Function<? super T,? extends C> classifier)`	Groups elements of this `Traversable` based on a classifier function.
`Iterator<? extends Traversable<T>>`	`grouped(int size)`	Splits this `Traversable` into consecutive blocks of the given size.
`boolean`	`hasDefiniteSize()`	Indicates whether this `Traversable` has a known finite size.
`int`	`hashCode()`	Returns the hash code of this collection.
`T`	`head()`	Returns the first element of this non-empty `Traversable`.
`default Option<T>`	`headOption()`	Returns the first element of this `Traversable` as an `Option`.
`Traversable<T>`	`init()`	Returns all elements of this Traversable except the last one.
`default Option<? extends Traversable<T>>`	`initOption()`	Returns all elements of this Traversable except the last one, wrapped in an `Option`.
`default boolean`	`isDistinct()`	Indicates whether this Traversable may contain only distinct elements.
`default boolean`	`isEmpty()`	Checks if this Traversable contains no elements.
`default boolean`	`isOrdered()`	Indicates whether this Traversable is ordered according to its natural or specified order.
`default boolean`	`isSequential()`	Indicates whether the elements of this Traversable appear in encounter (insertion) order.
`default boolean`	`isSingleValued()`	Indicates that this Traversable may contain multiple elements.
`boolean`	`isTraversableAgain()`	Checks if this Traversable can be traversed multiple times without side effects.
`default @NonNull Iterator<T>`	`iterator()`	Returns an iterator over the elements of this Traversable, implemented via `head()` and `tail()`.
`T`	`last()`	Returns the last element of this Traversable.
`default Option<T>`	`lastOption()`	Returns the last element of this Traversable as an `Option`.
`int`	`length()`	Returns the number of elements in this Traversable.
`<U> Traversable<U>`	`map(@NonNull java.util.function.Function<? super T,? extends U> mapper)`	Transforms the elements of this Traversable to a new type, preserving order if defined.
`default <U> Traversable<U>`	`mapTo(U value)`	Maps the underlying value to another fixed value.
`default Traversable<java.lang.Void>`	`mapToVoid()`	Maps the underlying value to Void
`default Option<T>`	`max()`	Returns the maximum element of this Traversable according to the natural order of its elements.
`default Option<T>`	`maxBy(@NonNull java.util.Comparator<? super T> comparator)`	Returns the maximum element of this Traversable according to the given comparator.
`default <U extends java.lang.Comparable<? super U>> Option<T>`	`maxBy(@NonNull java.util.function.Function<? super T,? extends U> f)`	Returns the element of this Traversable whose mapped value, according to the given function, is maximal.
`default Option<T>`	`min()`	Returns the minimum element of this Traversable according to its natural order in O(n).
`default Option<T>`	`minBy(@NonNull java.util.Comparator<? super T> comparator)`	Returns the minimum element of this Traversable according to a given comparator.
`default <U extends java.lang.Comparable<? super U>> Option<T>`	`minBy(@NonNull java.util.function.Function<? super T,? extends U> f)`	Returns the element of this Traversable whose mapped value is minimal according to natural order.
`default CharSeq`	`mkCharSeq()`	Concatenates the string representations of all elements in this Traversable.
`default CharSeq`	`mkCharSeq(java.lang.CharSequence delimiter)`	Concatenates the string representations of all elements in this Traversable, separated by a delimiter.
`default CharSeq`	`mkCharSeq(java.lang.CharSequence prefix, java.lang.CharSequence delimiter, java.lang.CharSequence suffix)`	Concatenates the string representations of all elements in this Traversable with a prefix, delimiter, and suffix.
`default java.lang.String`	`mkString()`	Concatenates the string representations of all elements in this Traversable.
`default java.lang.String`	`mkString(java.lang.CharSequence delimiter)`	Concatenates the string representations of all elements in this Traversable, separated by a delimiter.
`default java.lang.String`	`mkString(java.lang.CharSequence prefix, java.lang.CharSequence delimiter, java.lang.CharSequence suffix)`	Concatenates the string representations of all elements in this Traversable with a prefix, delimiter, and suffix.
`static <T> Traversable<T>`	`narrow(Traversable<? extends T> traversable)`	Narrows a `Traversable<? extends T>` to `Traversable<T>` with a type-safe cast.
`default boolean`	`nonEmpty()`	Checks if this `Traversable` contains at least one element.
`Traversable<T>`	`orElse(@NonNull java.util.function.Supplier<? extends java.lang.Iterable<? extends T>> supplier)`	Returns this `Traversable` if it is non-empty; otherwise, returns the result of evaluating the given supplier.
`Traversable<T>`	`orElse(java.lang.Iterable<? extends T> other)`	Returns this `Traversable` if it is non-empty; otherwise, returns the given alternative.
`Tuple2<? extends Traversable<T>,? extends Traversable<T>>`	`partition(@NonNull java.util.function.Predicate<? super T> predicate)`	Splits this `Traversable` into two partitions according to a predicate.
`Traversable<T>`	`peek(@NonNull java.util.function.Consumer<? super T> action)`	Performs the given `action` on the first element if this is an eager implementation.
`default java.lang.Number`	`product()`	Calculates the product of the elements in this `Traversable`.
`default T`	`reduceLeft(@NonNull java.util.function.BiFunction<? super T,? super T,? extends T> op)`	Reduces the elements of this Traversable from the left using the given binary operation.
`default Option<T>`	`reduceLeftOption(@NonNull java.util.function.BiFunction<? super T,? super T,? extends T> op)`	Reduces the elements of this Traversable from the left using the given binary operation, returning the result wrapped in an `Option`.
`default T`	`reduceRight(@NonNull java.util.function.BiFunction<? super T,? super T,? extends T> op)`	Reduces the elements of this Traversable from the right using the given binary operation.
`default Option<T>`	`reduceRightOption(@NonNull java.util.function.BiFunction<? super T,? super T,? extends T> op)`	Reduces the elements of this Traversable from the right using the given binary operation, returning the result wrapped in an `Option`.
`default Traversable<T>`	`reject(@NonNull java.util.function.Predicate<? super T> predicate)`	Returns a new traversable containing only the elements that do not satisfy the given predicate.
`Traversable<T>`	`replace(T currentElement, T newElement)`	Replaces the first occurrence of `currentElement` with `newElement`, if it exists.
`Traversable<T>`	`replaceAll(T currentElement, T newElement)`	Replaces all occurrences of `currentElement` with `newElement`.
`Traversable<T>`	`retainAll(@NonNull java.lang.Iterable<? extends T> elements)`	Retains only the elements from this Traversable that are contained in the given `elements`.
`Traversable<T>`	`scan(T zero, @NonNull java.util.function.BiFunction<? super T,? super T,? extends T> operation)`	Computes a prefix scan of the elements of this Traversable.
`<U> Traversable<U>`	`scanLeft(U zero, @NonNull java.util.function.BiFunction<? super U,? super T,? extends U> operation)`	Produces a collection containing cumulative results of applying the operator from left to right.
`<U> Traversable<U>`	`scanRight(U zero, @NonNull java.util.function.BiFunction<? super T,? super U,? extends U> operation)`	Produces a collection containing cumulative results of applying the operator from right to left.
`default T`	`single()`	Returns the single element of this Traversable.
`default Option<T>`	`singleOption()`	Returns the single element of this Traversable as an `Option`.
`default int`	`size()`	Returns the number of elements in this Traversable.
`Iterator<? extends Traversable<T>>`	`slideBy(@NonNull java.util.function.Function<? super T,?> classifier)`	Partitions this `Traversable` into consecutive non-overlapping windows according to a classification function.
`Iterator<? extends Traversable<T>>`	`sliding(int size)`	Slides a window of a given `size` over this `Traversable` with a step size of 1.
`Iterator<? extends Traversable<T>>`	`sliding(int size, int step)`	Slides a window of a specific `size` with a given `step` over this `Traversable`.
`Tuple2<? extends Traversable<T>,? extends Traversable<T>>`	`span(@NonNull java.util.function.Predicate<? super T> predicate)`	Splits this `Traversable` into a prefix and remainder according to the given `predicate`.
`default java.util.Spliterator<T>`	`spliterator()`
`default java.lang.Number`	`sum()`	Calculates the sum of the elements in this `Traversable`.
`Traversable<T>`	`tail()`	Returns a new `Traversable` without its first element.
`default Option<? extends Traversable<T>>`	`tailOption()`	Returns a new `Traversable` without its first element as an `Option`.
`Traversable<T>`	`take(int n)`	Returns the first `n` elements of this `Traversable`, or all elements if `n` exceeds the length.
`Traversable<T>`	`takeRight(int n)`	Returns the last `n` elements of this `Traversable`, or all elements if `n` exceeds the length.
`Traversable<T>`	`takeUntil(@NonNull java.util.function.Predicate<? super T> predicate)`	Takes elements from this `Traversable` until the given predicate holds for an element.
`Traversable<T>`	`takeWhile(@NonNull java.util.function.Predicate<? super T> predicate)`	Takes elements from this `Traversable` while the given predicate holds.
`<T1,T2> Tuple2<? extends Traversable<T1>,? extends Traversable<T2>>`	`unzip(@NonNull java.util.function.Function<? super T,Tuple2<? extends T1,? extends T2>> unzipper)`	Unzips the elements of this `Traversable` by mapping each element to a pair and splitting them into two separate `Traversable` collections.
`<T1,T2,T3> Tuple3<? extends Traversable<T1>,? extends Traversable<T2>,? extends Traversable<T3>>`	`unzip3(@NonNull java.util.function.Function<? super T,Tuple3<? extends T1,? extends T2,? extends T3>> unzipper)`	Unzips the elements of this `Traversable` by mapping each element to a triple and splitting them into three separate `Traversable` collections.
`<U> Traversable<Tuple2<T,U>>`	`zip(@NonNull java.lang.Iterable<? extends U> that)`	Returns a `Traversable` formed by pairing elements of this `Traversable` with elements of another `Iterable`.
`<U> Traversable<Tuple2<T,U>>`	`zipAll(@NonNull java.lang.Iterable<? extends U> that, T thisElem, U thatElem)`	Returns a `Traversable` formed by pairing elements of this `Traversable` with elements of another `Iterable`, filling in placeholder elements when one collection is shorter than the other.
`<U,R> Traversable<R>`	`zipWith(@NonNull java.lang.Iterable<? extends U> that, java.util.function.BiFunction<? super T,? super U,? extends R> mapper)`	Returns a `Traversable` by combining elements of this `Traversable` with elements of another `Iterable` using a mapping function.
`Traversable<Tuple2<T,java.lang.Integer>>`	`zipWithIndex()`	Zips this `Traversable` with its indices, starting at 0.
`<U> Traversable<U>`	`zipWithIndex(@NonNull java.util.function.BiFunction<? super T,? super java.lang.Integer,? extends U> mapper)`	Zips this `Traversable` with its indices and maps the resulting pairs using the provided mapper.

Methods inherited from interface io.vavr.collection.Foldable
fold, reduce, reduceOption

Methods inherited from interface io.vavr.Value
collect, collect, contains, corresponds, eq, exists, forAll, forEach, getOrElse, getOrElse, getOrElseThrow, getOrElseTry, getOrNull, isAsync, isLazy, out, out, stderr, stdout, stringPrefix, toArray, toCharSeq, toCompletableFuture, toEither, toEither, toInvalid, toInvalid, toJavaArray, toJavaArray, toJavaArray, toJavaCollection, toJavaList, toJavaList, toJavaMap, toJavaMap, toJavaMap, toJavaOptional, toJavaParallelStream, toJavaSet, toJavaSet, toJavaStream, toLeft, toLeft, toLinkedMap, toLinkedMap, toLinkedSet, toList, toMap, toMap, toOption, toPriorityQueue, toPriorityQueue, toQueue, toRight, toRight, toSet, toSortedMap, toSortedMap, toSortedMap, toSortedMap, toSortedSet, toSortedSet, toStream, toString, toTree, toTree, toTry, toTry, toValid, toValid, toValidation, toValidation, toVector

- Method Detail
 - narrow
```
static <T> Traversable<T> narrow(Traversable<? extends T> traversable)
```
 Narrows a Traversable<? extends T> to Traversable<T> with a type-safe cast.
 This is safe because immutable or read-only collections are covariant in their element type.
 
 Type Parameters:
 
 T - the element type of the resulting Traversable
 
 Parameters:
 
 traversable - the Traversable instance to narrow
 
 Returns:
 
 the same traversable instance with type Traversable<T>
 - arrangeBy
```
default <K> Option<Map<K,T>> arrangeBy(@NonNull java.util.function.Function<? super T,? extends K> getKey)
```
 Groups elements by a unique key extracted from each element.
 Returns None if any key occurs more than once; otherwise, returns a Map where each key is associated with its corresponding element.
 
 Type Parameters:
 
 K - the type of keys
 
 Parameters:
 
 getKey - a function to extract a key from each element
 
 Returns:
 
 an Option containing the Map of elements by key, or None if keys are not unique
 
 Throws:
 
 java.lang.NullPointerException - if getKey is null
 
 See Also:
 
 groupBy(Function)
 - average
```
default Option<java.lang.Double> average()
```
 Computes the average of the elements, assuming they are of type Number.
 If the elements are not numeric, an UnsupportedOperationException is thrown.
 Examples:
 List.empty().average() // = None List.of(1, 2, 3).average() // = Some(2.0) List.of(1.0, 1e100, 2.0, -1e100).average() // = Some(0.75) List.of(1.0, Double.NaN).average() // = NaN List.of("apple", "pear").average() // throws
 
 Unlike Java's DoubleStream.average() which uses the Kahan summation algorithm, Vavr uses Neumaier's modification of Kahan's algorithm for improved numerical accuracy.
 Returns:
 
 Some(average) if the sequence has elements, otherwise None
 
 Throws:
 
 java.lang.UnsupportedOperationException - if any element is not numeric
 - collect
```
<R> Traversable<R> collect(@NonNull PartialFunction<? super T,? extends R> partialFunction)
```
 Applies a PartialFunction to all elements that are defined for it and collects the results.
 For each element in iteration order, the function is first tested:
 partialFunction.isDefinedAt(element)
 If true, the element is mapped to type R:
 R newElement = partialFunction.apply(element)
 
 Note: If this Traversable is ordered (i.e., extends Ordered), the caller must ensure that the resulting elements are comparable (i.e., implement Comparable).
 Type Parameters:
 
 R - the type of elements in the resulting Traversable
 
 Parameters:
 
 partialFunction - a function that may not be defined for all elements of this traversable
 
 Returns:
 
 a new Traversable containing the results of applying the partial function
 
 Throws:
 
 java.lang.NullPointerException - if partialFunction is null
 - containsAll
```
default boolean containsAll(@NonNull java.lang.Iterable<? extends T> elements)
```
 Checks whether this Traversable contains all elements from the given iterable.
 Equivalent to testing each element individually:
 elements.isEmpty() ? true : contains(elements.head()) && containsAll(elements.tail())
 but implemented efficiently without recursion.
 Parameters:
 
 elements - an Iterable of elements to check for containment
 
 Returns:
 
 true if all elements are present, false otherwise
 
 Throws:
 
 java.lang.NullPointerException - if elements is null
 - count
```
default int count(@NonNull java.util.function.Predicate<? super T> predicate)
```
 Counts the number of elements that satisfy the given predicate.
 
 Parameters:
 
 predicate - a condition to test each element
 
 Returns:
 
 the number of elements matching the predicate (always >= 0)
 
 Throws:
 
 java.lang.NullPointerException - if predicate is null
 - distinct
```
Traversable<T> distinct()
```
 Returns a new Traversable containing the elements of this instance with all duplicates removed. Element equality is determined using equals.
 
 Returns:
 
 a new Traversable without duplicate elements
 - distinctBy
```
Traversable<T> distinctBy(@NonNull java.util.Comparator<? super T> comparator)
```
 Returns a new Traversable containing the elements of this instance without duplicates, as determined by the given comparator.
 
 Parameters:
 
 comparator - a comparator used to determine equality of elements
 
 Returns:
 
 a new Traversable with duplicates removed
 
 Throws:
 
 java.lang.NullPointerException - if comparator is null
 - distinctBy
```
 Traversable<T> distinctBy(@NonNull java.util.function.Function<? super T,? extends U> keyExtractor)
```
 Returns a new Traversable containing the elements of this instance without duplicates, based on keys extracted from elements using keyExtractor.
 The first occurrence of each key is retained in the resulting sequence.
 
 Type Parameters:
 
 U - the type of key
 
 Parameters:
 
 keyExtractor - a function to extract keys for determining uniqueness
 
 Returns:
 
 a new Traversable with duplicates removed based on keys
 
 Throws:
 
 java.lang.NullPointerException - if keyExtractor is null
 - drop
```
Traversable<T> drop(int n)
```
 Returns a new Traversable without the first n elements, or an empty instance if this contains fewer than n elements.
 
 Parameters:
 
 n - the number of elements to drop
 
 Returns:
 
 a new instance excluding the first n elements
 - dropRight
```
Traversable<T> dropRight(int n)
```
 Returns a new Traversable without the last n elements, or an empty instance if this contains fewer than n elements.
 
 Parameters:
 
 n - the number of elements to drop from the end
 
 Returns:
 
 a new instance excluding the last n elements
 - dropUntil
```
Traversable<T> dropUntil(@NonNull java.util.function.Predicate<? super T> predicate)
```
 Returns a new Traversable starting from the first element that satisfies the given predicate, dropping all preceding elements.
 
 Parameters:
 
 predicate - a condition tested on each element
 
 Returns:
 
 a new instance starting from the first element matching the predicate
 
 Throws:
 
 java.lang.NullPointerException - if predicate is null
 - dropWhile
```
Traversable<T> dropWhile(@NonNull java.util.function.Predicate<? super T> predicate)
```
 Returns a new Traversable starting from the first element that does not satisfy the given predicate, dropping all preceding elements.
 This is equivalent to dropUntil(predicate.negate()), which is useful for method references that cannot be negated directly.
 
 Parameters:
 
 predicate - a condition tested on each element
 
 Returns:
 
 a new instance starting from the first element not matching the predicate
 
 Throws:
 
 java.lang.NullPointerException - if predicate is null
 - equals
```
boolean equals(java.lang.Object obj)
```
 Determines whether this collection is equal to the given object.
 In Vavr, there are four basic collection types:
 
 Seq – sequential elements
 
 Set – distinct elements
 
 Map – key-value pairs
 
 Multimap – keys mapped to multiple values
 
 Two collections are considered equal if and only if:
 
 They are of the same collection type (Seq, Set, Map, Multimap)
 
 They contain the same elements
 
 For Seq, the element order is the same
 
 For Map and Multimap, two entries (key1, value1) and (key2, value2) are equal if both their keys and values are equal.
 Additional notes:
 
 No collection equals null (e.g., Queue(1) != null)
 
 Null elements are allowed and treated as expected (e.g., List(null, 1) == Stream(null, 1), HashMap((null,1)) == LinkedHashMap((null,1)))
 
 Element order matters only for Seq
 
 Other collection classes are equal if their types and elements (in iteration order) are equal
 
 Iterators are compared by reference only
 Specified by:
 
 equals in interface Value<T>
 
 Overrides:
 
 equals in class java.lang.Object
 
 Parameters:
 
 obj - the object to compare with, may be null
 
 Returns:
 
 true if the collections are equal according to the rules above, false otherwise
 - existsUnique
```
default boolean existsUnique(@NonNull java.util.function.Predicate<? super T> predicate)
```
 Checks whether there is exactly one element in this traversable for which the given predicate holds.
 
 Parameters:
 
 predicate - the condition to test elements
 
 Returns:
 
 true if exactly one element satisfies the predicate, false otherwise
 
 Throws:
 
 java.lang.NullPointerException - if predicate is null
 - filter
```
Traversable<T> filter(@NonNull java.util.function.Predicate<? super T> predicate)
```
 Returns a new traversable containing only the elements that satisfy the given predicate.
 
 Parameters:
 
 predicate - the condition to test elements
 
 Returns:
 
 a traversable with elements matching the predicate
 
 Throws:
 
 java.lang.NullPointerException - if predicate is null
 - reject
```
default Traversable<T> reject(@NonNull java.util.function.Predicate<? super T> predicate)
```
 Returns a new traversable containing only the elements that do not satisfy the given predicate.
 This is equivalent to filter(predicate.negate()).
 
 Parameters:
 
 predicate - the condition to test elements
 
 Returns:
 
 a traversable with elements not matching the predicate
 
 Throws:
 
 java.lang.NullPointerException - if predicate is null
 - find
```
default Option<T> find(@NonNull java.util.function.Predicate<? super T> predicate)
```
 Returns the first element that satisfies the given predicate.
 
 Parameters:
 
 predicate - the condition to test elements
 
 Returns:
 
 Some(element) if a matching element is found, otherwise None; the element may be null
 
 Throws:
 
 java.lang.NullPointerException - if predicate is null
 - findLast
```
default Option<T> findLast(@NonNull java.util.function.Predicate<? super T> predicate)
```
 Returns the last element that satisfies the given predicate.
 Equivalent to reverse().find(predicate) but potentially more efficient.
 
 Parameters:
 
 predicate - the condition to test elements
 
 Returns:
 
 Some(element) if a matching element is found, otherwise None; the element may be null
 
 Throws:
 
 java.lang.NullPointerException - if predicate is null
 - flatMap
```
 Traversable flatMap(@NonNull java.util.function.Function<? super T,? extends java.lang.Iterable<? extends U>> mapper)
```
 Transforms each element of this Traversable into an Iterable of elements and flattens the resulting iterables into a single Traversable.
 
 Type Parameters:
 
 U - the type of elements in the resulting Traversable
 
 Parameters:
 
 mapper - a function mapping elements to iterables
 
 Returns:
 
 a new Traversable containing all elements produced by applying mapper and flattening
 
 Throws:
 
 java.lang.NullPointerException - if mapper is null
 - foldLeft
```
default  U foldLeft(U zero,
 @NonNull java.util.function.BiFunction<? super U,? super T,? extends U> f)
```
 Description copied from interface: Foldable
 Folds the elements of this structure from the left, starting with the given zero value and successively applying the combine function to each element.
 Folding from the left means that elements are combined in the order they are encountered, associating each step with the accumulated result so far.
 Example:
 // Result: "cba!" List.of("a", "b", "c").foldLeft("!", (acc, x) -> x + acc);
 Specified by:
 
 foldLeft in interface Foldable<T>
 
 Type Parameters:
 
 U - the type of the accumulated result
 
 Parameters:
 
 zero - the initial value to start folding with
 
 f - a function that combines the accumulated value and the next element
 
 Returns:
 
 the folded result
 - foldRight
```
 U foldRight(U zero,
 @NonNull java.util.function.BiFunction<? super T,? super U,? extends U> f)
```
 Description copied from interface: Foldable
 Folds the elements of this structure from the right, starting with the given zero value and successively applying the combine function to each element.
 Folding from the right means that elements are combined starting from the last element and associating each step with the accumulated result so far.
 Example:
 // Result: "!cba" List.of("a", "b", "c").foldRight("!", (x, acc) -> acc + x);
 Specified by:
 
 foldRight in interface Foldable<T>
 
 Type Parameters:
 
 U - the type of the accumulated result
 
 Parameters:
 
 zero - the initial value to start folding with
 
 f - a function that combines the next element and the accumulated value
 
 Returns:
 
 the folded result
 - forEachWithIndex
```
default void forEachWithIndex(@NonNull java.util.function.ObjIntConsumer<? super T> action)
```
 Performs the given action on each element of this Traversable along with its index.
 This method is more efficient than iterator().zipWithIndex().forEach() because it avoids creating intermediate Tuple2 objects and boxing integers.
 
 Note that the iteration order may vary between calls depending on the underlying Traversable implementation. Also, if this Traversable is lazily evaluated (e.g., a Stream), the method may loop indefinitely.
 
 Parameters:
 
 action - an action to perform on each element and its index
 
 Throws:
 
 java.lang.NullPointerException - if action is null
 - get
```
default T get()
```
 Returns the first element of this Traversable in iteration order.
 
 Specified by:
 
 get in interface Value<T>
 
 Returns:
 
 the first element
 
 Throws:
 
 java.util.NoSuchElementException - if this Traversable is empty
 - groupBy
```
<C> Map<C,? extends Traversable<T>> groupBy(@NonNull java.util.function.Function<? super T,? extends C> classifier)
```
 Groups elements of this Traversable based on a classifier function.
 
 Type Parameters:
 
 C - The type of the group keys
 
 Parameters:
 
 classifier - A function that assigns each element to a group
 
 Returns:
 
 A map where each key corresponds to a group of elements
 
 Throws:
 
 java.lang.NullPointerException - if classifier is null
 
 See Also:
 
 arrangeBy(Function)
 - grouped
```
Iterator<? extends Traversable<T>> grouped(int size)
```
 Splits this Traversable into consecutive blocks of the given size.
 Let length be the number of elements in this Traversable:
 
 If empty, the resulting Iterator is empty.
 
 If size <= length, the resulting Iterator contains length / size blocks of size size and possibly a final smaller block of size length % size.
 
 If size > length, the resulting Iterator contains a single block of size length.
 
 Examples:
 
 [].grouped(1) = [] [].grouped(0) throws [].grouped(-1) throws [1,2,3,4].grouped(2) = [[1,2],[3,4]] [1,2,3,4,5].grouped(2) = [[1,2],[3,4],[5]] [1,2,3,4].grouped(5) = [[1,2,3,4]]
 
 Note: grouped(size) is equivalent to sliding(size, size).
 Parameters:
 
 size - the block size; must be positive
 
 Returns:
 
 an Iterator over blocks of elements
 
 Throws:
 
 java.lang.IllegalArgumentException - if size is zero or negative
 - hasDefiniteSize
```
boolean hasDefiniteSize()
```
 Indicates whether this Traversable has a known finite size.
 This should typically be implemented by concrete classes, not interfaces.
 
 Returns:
 
 true if the number of elements is finite and known, false otherwise.
 - head
```
T head()
```
 Returns the first element of this non-empty Traversable.
 
 Returns:
 
 the first element
 
 Throws:
 
 java.util.NoSuchElementException - if this Traversable is empty
 - headOption
```
default Option<T> headOption()
```
 Returns the first element of this Traversable as an Option.
 
 Returns:
 
 Some(element) if non-empty, otherwise None
 - hashCode
```
int hashCode()
```
 Returns the hash code of this collection.
 Vavr distinguishes between collections with predictable iteration order (like Seq) and collections with arbitrary iteration order (like Set, Map, and Multimap). In all cases, the hash of an empty collection is defined as 1.
 
 For collections with predictable iteration order, the hash is computed as:
 
 int hash = 1; for (T t : this) { hash = hash * 31 + Objects.hashCode(t); }
 
 For collections with arbitrary iteration order, the hash is computed to be independent of element order:
 
 int hash = 1; for (T t : this) { hash += Objects.hashCode(t); }
 
 Note that these algorithms may change in future Vavr versions. Hash codes are generally not cached, unlike size/length, because caching would increase memory usage due to persistent tree-based structures. Computing the hash code is linear in time, O(n). For frequently re-used collections (e.g., as HashMap keys), caching can be done externally using a wrapper, for example:
 
 {@code public final class Hashed { private final K key; private final Lazy hashCode; public Hashed(K key) { this.key = key; this.hashCode = Lazy.of(() -> Objects.hashCode(key)); } public K key() { return key; }
 Specified by:
 
 hashCode in interface Value<T>
 
 Overrides:
 
 hashCode in class java.lang.Object
 
 Returns:
 
 the hash code of this collection
 - init
```
Traversable<T> init()
```
 Returns all elements of this Traversable except the last one.
 This is the dual of tail().
 
 Returns:
 
 a new instance containing all elements except the last
 
 Throws:
 
 java.lang.UnsupportedOperationException - if this Traversable is empty
 - initOption
```
default Option<? extends Traversable<T>> initOption()
```
 Returns all elements of this Traversable except the last one, wrapped in an Option.
 This is the dual of tailOption().
 
 Returns:
 
 Some(traversable) if non-empty, or None if this Traversable is empty
 - isDistinct
```
default boolean isDistinct()
```
 Indicates whether this Traversable may contain only distinct elements.
 
 Returns:
 
 true if this Traversable may contain only distinct elements, false otherwise
 - isEmpty
```
default boolean isEmpty()
```
 Checks if this Traversable contains no elements.
 
 Specified by:
 
 isEmpty in interface Value<T>
 
 Returns:
 
 true if empty, false otherwise
 - isOrdered
```
default boolean isOrdered()
```
 Indicates whether this Traversable is ordered according to its natural or specified order.
 
 Returns:
 
 true if this Traversable is ordered, false otherwise
 - isSequential
```
default boolean isSequential()
```
 Indicates whether the elements of this Traversable appear in encounter (insertion) order.
 
 Returns:
 
 true if insertion order is preserved, false otherwise
 - isSingleValued
```
default boolean isSingleValued()
```
 Indicates that this Traversable may contain multiple elements.
 
 Specified by:
 
 isSingleValued in interface Value<T>
 
 Returns:
 
 false since Traversable is multi-valued by design
 - isTraversableAgain
```
boolean isTraversableAgain()
```
 Checks if this Traversable can be traversed multiple times without side effects.
 Implementations should provide the correct behavior; this is not meant for interfaces alone.
 
 Returns:
 
 true if this Traversable is guaranteed to be repeatably traversable, false otherwise
 - iterator
```
default @NonNull Iterator<T> iterator()
```
 Returns an iterator over the elements of this Traversable, implemented via head() and tail(). Subclasses may override for a more efficient implementation.
 
 Specified by:
 
 iterator in interface java.lang.Iterable<T>
 
 Specified by:
 
 iterator in interface Value<T>
 
 Returns:
 
 a new Iterator over the elements of this Traversable
 - last
```
T last()
```
 Returns the last element of this Traversable.
 
 Returns:
 
 the last element
 
 Throws:
 
 java.util.NoSuchElementException - if this Traversable is empty
 - lastOption
```
default Option<T> lastOption()
```
 Returns the last element of this Traversable as an Option.
 
 Returns:
 
 Some(element) if not empty, otherwise None
 - length
```
int length()
```
 Returns the number of elements in this Traversable.
 Equivalent to size().
 
 Returns:
 
 the number of elements
 - map
```
 Traversable map(@NonNull java.util.function.Function<? super T,? extends U> mapper)
```
 Transforms the elements of this Traversable to a new type, preserving order if defined.
 
 Specified by:
 
 map in interface Value<T>
 
 Type Parameters:
 
 U - the target element type
 
 Parameters:
 
 mapper - a mapping function
 
 Returns:
 
 a new Traversable containing the mapped elements
 
 Throws:
 
 java.lang.NullPointerException - if mapper is null
 - mapTo
```
default  Traversable mapTo(U value)
```
 Description copied from interface: Value
 
 Maps the underlying value to another fixed value.
 
 Specified by:
 
 mapTo in interface Value<T>
 
 Type Parameters:
 
 U - The new component type
 
 Parameters:
 
 value - value to replace the contents with
 
 Returns:
 
 A new value
 - mapToVoid
```
default Traversable<java.lang.Void> mapToVoid()
```
 Description copied from interface: Value
 
 Maps the underlying value to Void
 
 Specified by:
 
 mapToVoid in interface Value<T>
 
 Returns:
 
 A new value of type Void
 - max
```
default Option<T> max()
```
 Returns the maximum element of this Traversable according to the natural order of its elements.
 Note that the underlying order of sorted collections is not considered—only the natural ordering of elements matters.
 Examples:
 List.empty().max() // = None List.of(1, 2, 3).max() // = Some(3) List.of("a", "b", "c").max() // = Some("c") List.of(1.0, Double.NaN).max() // = NaN List.of(1, "a").max() // throws ClassCastException
 Returns:
 
 Some(maximum) if this Traversable is not empty, otherwise None
 
 Throws:
 
 java.lang.NullPointerException - if any element is null
 
 java.lang.ClassCastException - if elements do not implement Comparable
 - maxBy
```
default Option<T> maxBy(@NonNull java.util.Comparator<? super T> comparator)
```
 Returns the maximum element of this Traversable according to the given comparator.
 If the Traversable is empty, None is returned.
 
 Parameters:
 
 comparator - a non-null Comparator to determine element ordering
 
 Returns:
 
 Some(maximum) if this Traversable is not empty, otherwise None
 
 Throws:
 
 java.lang.NullPointerException - if comparator is null
 - maxBy
```
default > Option<T> maxBy(@NonNull java.util.function.Function<? super T,? extends U> f)
```
 Returns the element of this Traversable whose mapped value, according to the given function, is maximal.
 The mapping function f transforms elements of type T to a comparable type U, and the element with the largest U value is returned.
 
 Type Parameters:
 
 U - the type used for comparison, must implement Comparable
 
 Parameters:
 
 f - a non-null function mapping elements to a comparable type
 
 Returns:
 
 Some(element) whose mapped value is maximal, or None if this Traversable is empty
 
 Throws:
 
 java.lang.NullPointerException - if f is null
 - min
```
default Option<T> min()
```
 Returns the minimum element of this Traversable according to its natural order in O(n).
 The underlying order of sorted collections is not considered. For numeric types Double and Float, if any element is NaN, the result is NaN instead of following the natural order.
 Examples:
 List.empty().min() // = None List.of(1, 2, 3).min() // = Some(1) List.of("a", "b", "c").min() // = Some("a") List.of(1.0, Double.NaN).min() // = NaN List.of(1, "a").min() // throws
 Returns:
 
 Some(minimum) of this elements, or None if this Traversable is empty
 
 Throws:
 
 java.lang.NullPointerException - if an element is null
 
 java.lang.ClassCastException - if the elements do not have a natural order, i.e., do not implement Comparable
 - minBy
```
default Option<T> minBy(@NonNull java.util.Comparator<? super T> comparator)
```
 Returns the minimum element of this Traversable according to a given comparator.
 
 Parameters:
 
 comparator - a non-null comparator used to determine ordering
 
 Returns:
 
 Some(minimum) of this elements, or None if this Traversable is empty
 
 Throws:
 
 java.lang.NullPointerException - if comparator is null
 - minBy
```
default > Option<T> minBy(@NonNull java.util.function.Function<? super T,? extends U> f)
```
 Returns the element of this Traversable whose mapped value is minimal according to natural order.
 
 Type Parameters:
 
 U - the type of the comparable value
 
 Parameters:
 
 f - a function mapping elements to a comparable value
 
 Returns:
 
 the element of type T whose mapped value is minimal, wrapped in Some, or None if empty
 
 Throws:
 
 java.lang.NullPointerException - if f is null
 - mkCharSeq
```
default CharSeq mkCharSeq()
```
 Concatenates the string representations of all elements in this Traversable.
 Equivalent to mkCharSeq("", "", "").
 
 Returns:
 
 a new CharSeq containing all elements concatenated
 - mkCharSeq
```
default CharSeq mkCharSeq(java.lang.CharSequence delimiter)
```
 Concatenates the string representations of all elements in this Traversable, separated by a delimiter.
 Equivalent to mkCharSeq("", delimiter, "").
 
 Parameters:
 
 delimiter - a string placed between elements
 
 Returns:
 
 a new CharSeq with elements separated by the delimiter
 - mkCharSeq
```
default CharSeq mkCharSeq(java.lang.CharSequence prefix,
 java.lang.CharSequence delimiter,
 java.lang.CharSequence suffix)
```
 Concatenates the string representations of all elements in this Traversable with a prefix, delimiter, and suffix.
 Example: List.of("a", "b", "c").mkCharSeq("Chars(", ", ", ")") = CharSeq.of("Chars(a, b, c)")
 
 Parameters:
 
 prefix - a string prepended to the result
 
 delimiter - a string placed between elements
 
 suffix - a string appended to the result
 
 Returns:
 
 a new CharSeq containing the formatted concatenation of elements
 - mkString
```
default java.lang.String mkString()
```
 Concatenates the string representations of all elements in this Traversable.
 Equivalent to mkString("", "", "").
 
 Returns:
 
 a new String containing all elements concatenated
 - mkString
```
default java.lang.String mkString(java.lang.CharSequence delimiter)
```
 Concatenates the string representations of all elements in this Traversable, separated by a delimiter.
 Equivalent to mkString("", delimiter, "").
 
 Parameters:
 
 delimiter - a string placed between elements
 
 Returns:
 
 a new String containing the concatenated elements
 - mkString
```
default java.lang.String mkString(java.lang.CharSequence prefix,
 java.lang.CharSequence delimiter,
 java.lang.CharSequence suffix)
```
 Concatenates the string representations of all elements in this Traversable with a prefix, delimiter, and suffix.
 Example: List.of("a", "b", "c").mkString("Chars(", ", ", ")") = "Chars(a, b, c)"
 
 Parameters:
 
 prefix - a string prepended to the result
 
 delimiter - a string placed between elements
 
 suffix - a string appended to the result
 
 Returns:
 
 a new String containing the formatted concatenation of elements
 - nonEmpty
```
default boolean nonEmpty()
```
 Checks if this Traversable contains at least one element.
 Equivalent to !isEmpty().
 
 Returns:
 
 true if this Traversable is not empty, false otherwise
 - orElse
```
Traversable<T> orElse(java.lang.Iterable<? extends T> other)
```
 Returns this Traversable if it is non-empty; otherwise, returns the given alternative.
 
 Parameters:
 
 other - an alternative Traversable to return if this is empty
 
 Returns:
 
 this Traversable if non-empty, otherwise other
 - orElse
```
Traversable<T> orElse(@NonNull java.util.function.Supplier<? extends java.lang.Iterable<? extends T>> supplier)
```
 Returns this Traversable if it is non-empty; otherwise, returns the result of evaluating the given supplier.
 
 Parameters:
 
 supplier - a supplier of an alternative Traversable if this is empty
 
 Returns:
 
 this Traversable if non-empty, otherwise the result of supplier.get()
 
 Throws:
 
 java.lang.NullPointerException - if supplier is null
 - partition
```
Tuple2<? extends Traversable<T>,? extends Traversable<T>> partition(@NonNull java.util.function.Predicate<? super T> predicate)
```
 Splits this Traversable into two partitions according to a predicate.
 The first partition contains all elements that satisfy the predicate, and the second contains all elements that do not. The original iteration order is preserved.
 
 Parameters:
 
 predicate - a predicate used to classify elements
 
 Returns:
 
 a Tuple2 containing the two resulting Traversable instances
 
 Throws:
 
 java.lang.NullPointerException - if predicate is null
 - peek
```
Traversable<T> peek(@NonNull java.util.function.Consumer<? super T> action)
```
 Description copied from interface: Value
 
 Performs the given action on the first element if this is an eager implementation. Performs the given action on all elements (the first immediately, successive deferred), if this is a lazy implementation.
 
 Specified by:
 
 peek in interface Value<T>
 
 Parameters:
 
 action - The action that will be performed on the element(s).
 
 Returns:
 
 this instance
 - product
```
default java.lang.Number product()
```
 Calculates the product of the elements in this Traversable.
 Supported element types are Byte, Double, Float, Integer, Long, Short, BigInteger, and BigDecimal.
 Examples:
 List.empty().product() // = 1 List.of(1, 2, 3).product() // = 6L List.of(0.1, 0.2, 0.3).product() // = 0.006 List.of("apple", "pear").product() // throws
 
 For type-safe multiplication of elements, consider using Foldable.fold(Object, BiFunction).
 Returns:
 
 a Number representing the product of the elements
 
 Throws:
 
 java.lang.UnsupportedOperationException - if the elements are not numeric
 - reduceLeft
```
default T reduceLeft(@NonNull java.util.function.BiFunction<? super T,? super T,? extends T> op)
```
 Reduces the elements of this Traversable from the left using the given binary operation.
 
 Specified by:
 
 reduceLeft in interface Foldable<T>
 
 Parameters:
 
 op - A binary operation combining two elements of type T
 
 Returns:
 
 the result of the reduction
 
 Throws:
 
 java.util.NoSuchElementException - if this Traversable is empty
 
 java.lang.NullPointerException - if op is null
 - reduceLeftOption
```
default Option<T> reduceLeftOption(@NonNull java.util.function.BiFunction<? super T,? super T,? extends T> op)
```
 Reduces the elements of this Traversable from the left using the given binary operation, returning the result wrapped in an Option.
 
 Specified by:
 
 reduceLeftOption in interface Foldable<T>
 
 Parameters:
 
 op - A binary operation combining two elements of type T
 
 Returns:
 
 Some(reduced value) or None if this Traversable is empty
 
 Throws:
 
 java.lang.NullPointerException - if op is null
 - reduceRight
```
default T reduceRight(@NonNull java.util.function.BiFunction<? super T,? super T,? extends T> op)
```
 Reduces the elements of this Traversable from the right using the given binary operation.
 
 Specified by:
 
 reduceRight in interface Foldable<T>
 
 Parameters:
 
 op - A binary operation combining two elements of type T
 
 Returns:
 
 the result of the reduction
 
 Throws:
 
 java.util.NoSuchElementException - if this Traversable is empty
 
 java.lang.NullPointerException - if op is null
 - reduceRightOption
```
default Option<T> reduceRightOption(@NonNull java.util.function.BiFunction<? super T,? super T,? extends T> op)
```
 Reduces the elements of this Traversable from the right using the given binary operation, returning the result wrapped in an Option.
 
 Specified by:
 
 reduceRightOption in interface Foldable<T>
 
 Parameters:
 
 op - A binary operation combining two elements of type T
 
 Returns:
 
 Some(reduced value) or None if this Traversable is empty
 
 Throws:
 
 java.lang.NullPointerException - if op is null
 - replace
```
Traversable<T> replace(T currentElement,
 T newElement)
```
 Replaces the first occurrence of currentElement with newElement, if it exists.
 
 Parameters:
 
 currentElement - the element to be replaced
 
 newElement - the replacement element
 
 Returns:
 
 a new Traversable with the first occurrence of currentElement replaced by newElement
 - replaceAll
```
Traversable<T> replaceAll(T currentElement,
 T newElement)
```
 Replaces all occurrences of currentElement with newElement.
 
 Parameters:
 
 currentElement - the element to be replaced
 
 newElement - the replacement element
 
 Returns:
 
 a new Traversable with all occurrences of currentElement replaced by newElement
 - retainAll
```
Traversable<T> retainAll(@NonNull java.lang.Iterable<? extends T> elements)
```
 Retains only the elements from this Traversable that are contained in the given elements.
 
 Parameters:
 
 elements - the elements to keep
 
 Returns:
 
 a new Traversable containing only the elements present in elements, in their original order
 
 Throws:
 
 java.lang.NullPointerException - if elements is null
 - scan
```
Traversable<T> scan(T zero,
 @NonNull java.util.function.BiFunction<? super T,? super T,? extends T> operation)
```
 Computes a prefix scan of the elements of this Traversable.
 The neutral element zero may be applied more than once.
 
 Parameters:
 
 zero - the neutral element for the operator
 
 operation - an associative binary operator
 
 Returns:
 
 a new Traversable containing the prefix scan of the elements
 
 Throws:
 
 java.lang.NullPointerException - if operation is null
 - scanLeft
```
 Traversable scanLeft(U zero,
 @NonNull java.util.function.BiFunction<? super U,? super T,? extends U> operation)
```
 Produces a collection containing cumulative results of applying the operator from left to right.
 Will not terminate for infinite collections. The results may vary across runs unless the collection is ordered.
 
 Type Parameters:
 
 U - the type of the resulting elements
 
 Parameters:
 
 zero - the initial value
 
 operation - a binary operator applied to the intermediate result and each element
 
 Returns:
 
 a new Traversable containing the cumulative results
 
 Throws:
 
 java.lang.NullPointerException - if operation is null
 - scanRight
```
 Traversable scanRight(U zero,
 @NonNull java.util.function.BiFunction<? super T,? super U,? extends U> operation)
```
 Produces a collection containing cumulative results of applying the operator from right to left.
 The head of the resulting collection is the last cumulative result. Will not terminate for infinite collections. Results may vary across runs unless the collection is ordered.
 
 Type Parameters:
 
 U - the type of the resulting elements
 
 Parameters:
 
 zero - the initial value
 
 operation - a binary operator applied to each element and the intermediate result
 
 Returns:
 
 a new Traversable containing the cumulative results
 
 Throws:
 
 java.lang.NullPointerException - if operation is null
 - single
```
default T single()
```
 Returns the single element of this Traversable.
 
 Returns:
 
 the single element
 
 Throws:
 
 java.util.NoSuchElementException - if the Traversable is empty or contains more than one element
 - singleOption
```
default Option<T> singleOption()
```
 Returns the single element of this Traversable as an Option.
 
 Returns:
 
 Some(element) if the Traversable contains exactly one element, or None otherwise.
 - size
```
default int size()
```
 Returns the number of elements in this Traversable.
 Alias for length().
 
 Returns:
 
 the number of elements
 - slideBy
```
Iterator<? extends Traversable<T>> slideBy(@NonNull java.util.function.Function<? super T,?> classifier)
```
 Partitions this Traversable into consecutive non-overlapping windows according to a classification function.
 Each window contains elements with the same class, as determined by classifier. Two consecutive elements belong to the same window only if classifier returns equal values for both. Otherwise, the current window ends and a new window begins with the next element.
 Examples:
 [].slideBy(Function.identity()) = [] [1,2,3,4,4,5].slideBy(Function.identity()) = [[1],[2],[3],[4,4],[5]] [1,2,3,10,12,5,7,20,29].slideBy(x -> x / 10) = [[1,2,3],[10,12],[5,7],[20,29]]
 Parameters:
 
 classifier - A function classifying elements into groups
 
 Returns:
 
 An Iterator of windows (grouped elements)
 
 Throws:
 
 java.lang.NullPointerException - if classifier is null
 - sliding
```
Iterator<? extends Traversable<T>> sliding(int size)
```
 Slides a window of a given size over this Traversable with a step size of 1.
 This is equivalent to calling sliding(int, int) with a step size of 1.
 
 Parameters:
 
 size - a positive window size
 
 Returns:
 
 An Iterator of windows, each containing up to size elements
 
 Throws:
 
 java.lang.IllegalArgumentException - if size is zero or negative
 - sliding
```
Iterator<? extends Traversable<T>> sliding(int size,
 int step)
```
 Slides a window of a specific size with a given step over this Traversable.
 Examples:
 [].sliding(1, 1) = [] [1,2,3,4,5].sliding(2, 3) = [[1,2],[4,5]] [1,2,3,4,5].sliding(2, 4) = [[1,2],[5]] [1,2,3,4,5].sliding(2, 5) = [[1,2]] [1,2,3,4].sliding(5, 3) = [[1,2,3,4],[4]]
 Parameters:
 
 size - a positive window size
 
 step - a positive step size
 
 Returns:
 
 an Iterator of windows with the given size and step
 
 Throws:
 
 java.lang.IllegalArgumentException - if size or step are zero or negative
 - span
```
Tuple2<? extends Traversable<T>,? extends Traversable<T>> span(@NonNull java.util.function.Predicate<? super T> predicate)
```
 Splits this Traversable into a prefix and remainder according to the given predicate.
 The first element of the returned Tuple is the longest prefix of elements satisfying predicate, and the second element is the remaining elements.
 
 Parameters:
 
 predicate - a predicate used to determine the prefix
 
 Returns:
 
 a Tuple containing the prefix and remainder
 
 Throws:
 
 java.lang.NullPointerException - if predicate is null
 - spliterator
```
default java.util.Spliterator<T> spliterator()
```
 Specified by:
 
 spliterator in interface java.lang.Iterable<T>
 
 Specified by:
 
 spliterator in interface Value<T>
 - sum
```
default java.lang.Number sum()
```
 Calculates the sum of the elements in this Traversable. Supported numeric types are Byte, Double, Float, Integer, Long, Short, BigInteger, and BigDecimal.
 Examples:
 List.empty().sum() // = 0 List.of(1, 2, 3).sum() // = 6L List.of(0.1, 0.2, 0.3).sum() // = 0.6 List.of("apple", "pear").sum() // throws
 
 See also Foldable.fold(Object, BiFunction) for type-safe summation of elements.
 Returns:
 
 a Number representing the sum of the elements
 
 Throws:
 
 java.lang.UnsupportedOperationException - if elements are not numeric
 - tail
```
Traversable<T> tail()
```
 Returns a new Traversable without its first element.
 
 Returns:
 
 a new Traversable containing all elements except the first
 
 Throws:
 
 java.lang.UnsupportedOperationException - if this Traversable is empty
 - tailOption
```
default Option<? extends Traversable<T>> tailOption()
```
 Returns a new Traversable without its first element as an Option.
 
 Returns:
 
 Some(traversable) if non-empty, otherwise None
 - take
```
Traversable<T> take(int n)
```
 Returns the first n elements of this Traversable, or all elements if n exceeds the length.
 Equivalent to sublist(0, max(0, min(length(), n))), but safe for n < 0 or n > length().
 If n < 0, an empty instance is returned. If n > length(), the full instance is returned.
 
 Parameters:
 
 n - the number of elements to take
 
 Returns:
 
 a new Traversable containing the first n elements
 - takeRight
```
Traversable<T> takeRight(int n)
```
 Returns the last n elements of this Traversable, or all elements if n exceeds the length.
 Equivalent to sublist(max(0, length() - n), length()), but safe for n < 0 or n > length().
 If n < 0, an empty instance is returned. If n > length(), the full instance is returned.
 
 Parameters:
 
 n - the number of elements to take from the end
 
 Returns:
 
 a new Traversable containing the last n elements
 - takeUntil
```
Traversable<T> takeUntil(@NonNull java.util.function.Predicate<? super T> predicate)
```
 Takes elements from this Traversable until the given predicate holds for an element.
 Equivalent to takeWhile(predicate.negate()), but useful when using method references that cannot be negated directly.
 
 Parameters:
 
 predicate - a condition tested sequentially on the elements
 
 Returns:
 
 a new Traversable containing all elements before the first one that satisfies the predicate
 
 Throws:
 
 java.lang.NullPointerException - if predicate is null
 - takeWhile
```
Traversable<T> takeWhile(@NonNull java.util.function.Predicate<? super T> predicate)
```
 Takes elements from this Traversable while the given predicate holds.
 
 Parameters:
 
 predicate - a condition tested sequentially on the elements
 
 Returns:
 
 a new Traversable containing all elements up to (but not including) the first one that does not satisfy the predicate
 
 Throws:
 
 java.lang.NullPointerException - if predicate is null
 - unzip
```
<T1,T2> Tuple2<? extends Traversable<T1>,? extends Traversable<T2>> unzip(@NonNull java.util.function.Function<? super T,Tuple2<? extends T1,? extends T2>> unzipper)
```
 Unzips the elements of this Traversable by mapping each element to a pair and splitting them into two separate Traversable collections.
 
 Type Parameters:
 
 T1 - type of the first element in the resulting pairs
 
 T2 - type of the second element in the resulting pairs
 
 Parameters:
 
 unzipper - a function that maps elements of this Traversable to pairs
 
 Returns:
 
 a Tuple2 containing two Traversable collections with the split elements
 
 Throws:
 
 java.lang.NullPointerException - if unzipper is null
 - unzip3
```
<T1,T2,T3> Tuple3<? extends Traversable<T1>,? extends Traversable<T2>,? extends Traversable<T3>> unzip3(@NonNull java.util.function.Function<? super T,Tuple3<? extends T1,? extends T2,? extends T3>> unzipper)
```
 Unzips the elements of this Traversable by mapping each element to a triple and splitting them into three separate Traversable collections.
 
 Type Parameters:
 
 T1 - type of the first element in the resulting triples
 
 T2 - type of the second element in the resulting triples
 
 T3 - type of the third element in the resulting triples
 
 Parameters:
 
 unzipper - a function that maps elements of this Traversable to triples
 
 Returns:
 
 a Tuple3 containing three Traversable collections with the split elements
 
 Throws:
 
 java.lang.NullPointerException - if unzipper is null
 - zip
```
 Traversable<Tuple2<T,U>> zip(@NonNull java.lang.Iterable<? extends U> that)
```
 Returns a Traversable formed by pairing elements of this Traversable with elements of another Iterable. Pairing stops when either collection runs out of elements; any remaining elements in the longer collection are ignored.
 The length of the resulting Traversable is the minimum of the lengths of this Traversable and that.
 
 Type Parameters:
 
 U - the type of elements in the second half of each pair
 
 Parameters:
 
 that - an Iterable providing the second element of each pair
 
 Returns:
 
 a new Traversable containing pairs of corresponding elements
 
 Throws:
 
 java.lang.NullPointerException - if that is null
 - zipAll
```
 Traversable<Tuple2<T,U>> zipAll(@NonNull java.lang.Iterable<? extends U> that,
 T thisElem,
 U thatElem)
```
 Returns a Traversable formed by pairing elements of this Traversable with elements of another Iterable, filling in placeholder elements when one collection is shorter than the other.
 The length of the resulting Traversable is the maximum of the lengths of this Traversable and that.
 If this Traversable is shorter than that, thisElem is used as a filler. Conversely, if that is shorter, thatElem is used.
 
 Type Parameters:
 
 U - the type of elements in the second half of each pair
 
 Parameters:
 
 that - an Iterable providing the second element of each pair
 
 thisElem - the element used to fill missing values if this Traversable is shorter than that
 
 thatElem - the element used to fill missing values if that is shorter than this Traversable
 
 Returns:
 
 a new Traversable containing pairs of elements, including fillers as needed
 
 Throws:
 
 java.lang.NullPointerException - if that is null
 - zipWith
```
<U,R> Traversable<R> zipWith(@NonNull java.lang.Iterable<? extends U> that,
 java.util.function.BiFunction<? super T,? super U,? extends R> mapper)
```
 Returns a Traversable by combining elements of this Traversable with elements of another Iterable using a mapping function. Pairing stops when either collection runs out of elements.
 The length of the resulting Traversable is the minimum of the lengths of this Traversable and that.
 
 Type Parameters:
 
 U - the type of elements in the second parameter of the mapper
 
 R - the type of elements in the resulting Traversable
 
 Parameters:
 
 that - an Iterable providing the second parameter of the mapper
 
 mapper - a function that combines elements from this and that into a new element
 
 Returns:
 
 a new Traversable containing mapped elements
 
 Throws:
 
 java.lang.NullPointerException - if that or mapper is null
 - zipWithIndex
```
Traversable<Tuple2<T,java.lang.Integer>> zipWithIndex()
```
 Zips this Traversable with its indices, starting at 0.
 
 Returns:
 
 a new Traversable containing each element paired with its index
 - zipWithIndex
```
 Traversable zipWithIndex(@NonNull java.util.function.BiFunction<? super T,? super java.lang.Integer,? extends U> mapper)
```
 Zips this Traversable with its indices and maps the resulting pairs using the provided mapper.
 
 Type Parameters:
 
 U - the type of elements in the resulting Traversable
 
 Parameters:
 
 mapper - a function mapping an element and its index to a new element
 
 Returns:
 
 a new Traversable containing the mapped elements
 
 Throws:
 
 java.lang.NullPointerException - if mapper is null

Interface Traversable<T>

Method Summary

Methods inherited from interface io.vavr.collection.Foldable

Methods inherited from interface io.vavr.Value

Method Detail

narrow

arrangeBy

average

collect

containsAll

count

distinct

distinctBy

distinctBy

drop

dropRight

dropUntil

dropWhile

equals

existsUnique

filter

reject

find

findLast

flatMap

foldLeft

foldRight

forEachWithIndex

get

groupBy

grouped

hasDefiniteSize

head

headOption

hashCode

init

initOption

isDistinct

isEmpty

isOrdered

isSequential

isSingleValued

isTraversableAgain

iterator

last

lastOption

length

map

mapTo

mapToVoid

max

maxBy

maxBy

min

minBy

minBy

mkCharSeq

mkCharSeq

mkCharSeq

mkString

mkString

mkString

nonEmpty

orElse

orElse

partition

peek

product

reduceLeft

reduceLeftOption

reduceRight

reduceRightOption

replace

replaceAll

retainAll

scan

scanLeft

scanRight

single

singleOption