Scala 3/API/scala.collection/IterableOnceOps

IterableOnceOps

trait IterableOnceOps[+A, +CC[_], +C]

This implementation trait can be mixed into an IterableOnce to get the basic methods that are shared between Iterator and Iterable.

This implementation trait can be mixed into an IterableOnce to get the basic methods that are shared between Iterator and Iterable. The IterableOnce must support multiple calls to iterator but may or may not return the same Iterator every time.

class Any

trait IterableOps[A, CC, C]

trait EvidenceIterableFactoryDefaults[A, CC, Ev]

class ArraySeq[A]

class ofRef[T]

class ofByte

class ofShort

class ofChar

class ofInt

class ofLong

class ofFloat

class ofDouble

class ofBoolean

class ofUnit

class UnrolledBuffer[T]

trait Iterable[A]

class AbstractIterable[A]

class AbstractMap[K, V]

class HashMap[K, V]

class IntMap[T]

class ListMap[K, V]

class LongMap[T]

class WithDefault[K, V]

class Map1[K, V]

class Map2[K, V]

class Map3[K, V]

class Map4[K, V]

class TreeMap[K, V]

class TreeSeqMap[K, V]

class VectorMap[K, V]

class AbstractMap[K, V]

class TrieMap[K, V]

class AnyRefMap[K, V]

class CollisionProofHashMap[K, V]

class HashMap[K, V]

class LinkedHashMap[K, V]

class ListMap[K, V]

class LongMap[V]

class WithDefault[K, V]

class OpenHashMap[Key, Value]

class TreeMap[K, V]

class SystemProperties

class AbstractSeq[A]

class LazyList[A]

class List[A]

class ::[A]

object Nil

class NumericRange[T]

class Inclusive[T]

class Exclusive[T]

class Queue[A]

class Range

class Inclusive

class Exclusive

class Stream[A]

object Empty

class Cons[A]

class Vector[A]

class WrappedString

class AbstractSeq[A]

class AbstractBuffer[A]

class ArrayBuffer[A]

class ArrayDeque[A]

class Queue[A]

class Stack[A]

class ListBuffer[A]

class ArraySeq[T]

class ofRef[T]

class ofByte

class ofShort

class ofChar

class ofInt

class ofLong

class ofFloat

class ofDouble

class ofBoolean

class ofUnit

class StringBuilder

class AbstractSet[A]

class ValueSet

class BitSet

class BitSet1

class BitSet2

class BitSetN

class HashSet[A]

class ListSet[A]

class ImmutableKeySet

class Set1[A]

class Set2[A]

class Set3[A]

class Set4[A]

class ImmutableKeySortedSet

class TreeSet[A]

class AbstractSet[A]

class BitSet

class HashSet[A]

class LinkedHashSet[A]

class TreeSet[A]

class AbstractView[A]

class AbstractMapView[K, V]

class Id[K, V]

class MapValues[K, V, W]

class FilterKeys[K, V]

class Filter[K, V]

class TapEach[K, V, U]

class AbstractSeqView[A]

class AbstractIndexedSeqView[A]

class Slice[A]

class StringView

class ArrayBufferView[A]

class Id[A]

class Reverse[A]

object Empty

class Single[A]

class Elems[A]

class Fill[A]

class Tabulate[A]

class Iterate[A]

class Unfold[A, S]

class Filter[A]

class DistinctBy[A, B]

class LeftPartitionMapped[A, A1, A2]

class RightPartitionMapped[A, A1, A2]

class Drop[A]

class DropRight[A]

class DropWhile[A]

class Take[A]

class TakeRight[A]

class TakeWhile[A]

class ScanLeft[A, B]

class Map[A, B]

class FlatMap[A, B]

class Collect[A, B]

class Concat[A]

class Zip[A, B]

class ZipAll[A, B]

class Appended[A]

class Prepended[A]

class Updated[A]

class ZipWithIndex[A]

class PadTo[A]

class AbstractIterable[A]

class PriorityQueue[A]

trait Map[K, V]

trait DefaultMap[K, V]

trait SeqMap[K, V]

trait SortedMap[K, V]

trait Map[K, V]

trait MultiMap[K, V]

trait Seq[A]

trait IndexedSeq[A]

trait IndexedSeq[T]

trait IndexedBuffer[A]

trait LinearSeq[A]

trait Seq[A]

trait Buffer[A]

class Accumulator[A, CC, C]

class AnyAccumulator[A]

class DoubleAccumulator

class IntAccumulator

class LongAccumulator

trait Set[A]

trait SortedSet[A]

trait BitSet

trait SortedSet[A]

trait Set[A]

trait View[A]

trait MapView[K, V]

trait SeqView[A]

trait IndexedSeqView[A]

class Sorted[A, B]

trait Iterable[A]

trait IterableFactoryDefaults[A, CC]

trait MapFactoryDefaults[K, V, CC, WithFilterCC]

class WeakHashMap[K, V]

trait MapOps[K, V, CC, C]

trait SortedMapFactoryDefaults[K, V, CC, WithFilterCC, UnsortedCC]

trait SortedMapOps[K, V, CC, C]

trait StrictOptimizedSortedMapOps[K, V, CC, C]

trait SortedMapOps[K, V, CC, C]

trait StrictOptimizedMapOps[K, V, CC, C]

trait MapOps[K, V, CC, C]

trait SeqOps[A, CC, C]

trait IndexedSeqOps[A, CC, C]

trait LinearSeqOps[A, CC, C]

trait StrictOptimizedLinearSeqOps[A, CC, C]

trait LinearSeqOps[A, CC, C]

trait StrictOptimizedSeqOps[A, CC, C]

trait ArrayDequeOps[A, CC, C]

trait SeqOps[A, CC, C]

trait SetOps[A, CC, C]

trait SortedSetOps[A, CC, C]

trait BitSetOps[C]

trait SortedSetFactoryDefaults[A, CC, WithFilterCC]

trait StrictOptimizedSortedSetOps[A, CC, C]

trait SortedSetOps[A, CC, C]

trait StrictOptimizedSetOps[A, CC, C]

trait SetOps[A, CC, C]

trait StrictOptimizedIterableOps[A, CC, C]

trait Iterator[A]

class AbstractIterator[A]

class GroupedIterator[B]

class BufferedLineIterator

class LineIterator

class MatchIterator

trait BufferedIterator[A]

Value members

Abstract methods

Builds a new collection by applying a partial function to all elements of this collection on which the function is defined.

Type Params

B: the element type of the returned collection.

Value Params

pf: the partial function which filters and maps the collection.

Returns

a new collection resulting from applying the given partial function pf to each element on which it is defined and collecting the results. The order of the elements is preserved.

Selects all elements except first n ones.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value Params

n: the number of elements to drop from this collection.

Returns

a collection consisting of all elements of this collection except the first n ones, or else the empty collection, if this collection has less than n elements. If n is negative, don't drop any elements.

Drops longest prefix of elements that satisfy a predicate.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value Params

p: The predicate used to test elements.

Returns

the longest suffix of this collection whose first element does not satisfy the predicate p.

Selects all elements of this collection which satisfy a predicate.

Value Params

p: the predicate used to test elements.

Returns

a new iterator consisting of all elements of this collection that satisfy the given predicate p. The order of the elements is preserved.

Selects all elements of this collection which do not satisfy a predicate.

Value Params

pred: the predicate used to test elements.

Returns

a new collection consisting of all elements of this collection that do not satisfy the given predicate pred. Their order may not be preserved.

Builds a new collection by applying a function to all elements of this collection and using the elements of the resulting collections.

For example:

def getWords(lines: Seq[String]): Seq[String] = lines flatMap (line => line split "\\W+")

The type of the resulting collection is guided by the static type of collection. This might cause unexpected results sometimes. For example:

// lettersOf will return a Seq[Char] of likely repeated letters, instead of a Set
def lettersOf(words: Seq[String]) = words flatMap (word => word.toSet)

// lettersOf will return a Set[Char], not a Seq
def lettersOf(words: Seq[String]) = words.toSet flatMap ((word: String) => word.toSeq)

// xs will be an Iterable[Int]
val xs = Map("a" -> List(11,111), "b" -> List(22,222)).flatMap(_._2)

// ys will be a Map[Int, Int]
val ys = Map("a" -> List(1 -> 11,1 -> 111), "b" -> List(2 -> 22,2 -> 222)).flatMap(_._2)

Type Params

B: the element type of the returned collection.

Value Params

f: the function to apply to each element.

Returns

a new collection resulting from applying the given collection-valued function f to each element of this collection and concatenating the results.

Converts this collection of traversable collections into a collection formed by the elements of these traversable collections.

The resulting collection's type will be guided by the type of collection. For example:

val xs = List(
           Set(1, 2, 3),
           Set(1, 2, 3)
         ).flatten
// xs == List(1, 2, 3, 1, 2, 3)

val ys = Set(
           List(1, 2, 3),
           List(3, 2, 1)
         ).flatten
// ys == Set(1, 2, 3)

Type Params

B: the type of the elements of each traversable collection.

Value Params

asIterable: an implicit conversion which asserts that the element type of this collection is a GenTraversable.

Returns

a new collection resulting from concatenating all element collections.

Builds a new collection by applying a function to all elements of this collection.

Type Params

B: the element type of the returned collection.

Value Params

f: the function to apply to each element.

Returns

a new collection resulting from applying the given function f to each element of this collection and collecting the results.

Produces a collection containing cumulative results of applying the operator going left to right, including the initial value.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Type Params

B: the type of the elements in the resulting collection

Value Params

op: the binary operator applied to the intermediate result and the element
z: the initial value

Returns

collection with intermediate results

Selects an interval of elements.

Selects an interval of elements. The returned collection is made up of all elements x which satisfy the invariant:

from <= indexOf(x) < until

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value Params

from: the lowest index to include from this collection.
until: the lowest index to EXCLUDE from this collection.

Returns

a collection containing the elements greater than or equal to index from extending up to (but not including) index until of this collection.

Splits this collection into a prefix/suffix pair according to a predicate.

Note: c span p is equivalent to (but possibly more efficient than) (c takeWhile p, c dropWhile p), provided the evaluation of the predicate p does not cause any side-effects.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value Params

p: the test predicate

Returns

a pair consisting of the longest prefix of this collection whose elements all satisfy p, and the rest of this collection.

Selects the first n elements.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value Params

n: the number of elements to take from this collection.

Returns

a collection consisting only of the first n elements of this collection, or else the whole collection, if it has less than n elements. If n is negative, returns an empty collection.

Takes longest prefix of elements that satisfy a predicate.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value Params

p: The predicate used to test elements.

Returns

the longest prefix of this collection whose elements all satisfy the predicate p.

Applies a side-effecting function to each element in this collection.

Applies a side-effecting function to each element in this collection. Strict collections will apply f to their elements immediately, while lazy collections like Views and LazyLists will only apply f on each element if and when that element is evaluated, and each time that element is evaluated.

Type Params

U: the return type of f

Value Params

f: a function to apply to each element in this collection

Returns

The same logical collection as this

Zips this collection with its indices.

Returns: A new collection containing pairs consisting of all elements of this collection paired with their index. Indices start at 0.
Example: List("a", "b", "c").zipWithIndex == List(("a", 0), ("b", 1), ("c", 2))

Concrete methods

Appends all elements of this collection to a string builder using start, end, and separator strings.

Appends all elements of this collection to a string builder using start, end, and separator strings. The written text begins with the string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.

Example:

scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

scala> a.addString(b , "List(" , ", " , ")")
res5: StringBuilder = List(1, 2, 3, 4)

Value Params

b: the string builder to which elements are appended.
end: the ending string.
sep: the separator string.
start: the starting string.

Returns

the string builder b to which elements were appended.

@inline

Appends all elements of this collection to a string builder using a separator string.

Appends all elements of this collection to a string builder using a separator string. The written text consists of the string representations (w.r.t. the method toString) of all elements of this collection, separated by the string sep.

Example:

scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

scala> a.addString(b, ", ")
res0: StringBuilder = 1, 2, 3, 4

Value Params

b: the string builder to which elements are appended.
sep: the separator string.

Returns

the string builder b to which elements were appended.

@inline

Appends all elements of this collection to a string builder.

Appends all elements of this collection to a string builder. The written text consists of the string representations (w.r.t. the method toString) of all elements of this collection without any separator string.

Example:

scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

scala> val h = a.addString(b)
h: StringBuilder = 1234

Value Params

b: the string builder to which elements are appended.

Returns

the string builder b to which elements were appended.

Finds the first element of the collection for which the given partial function is defined, and applies the partial function to it.

Note: may not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value Params

pf: the partial function

Returns

an option value containing pf applied to the first value for which it is defined, or None if none exists.

Example

Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)

@deprecatedOverriding("This should always forward to the 3-arg version of this method", since = "2.13.4")

Copy elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with values of this collection.

Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.

Type Params

B: the type of the elements of the array.

Value Params

xs: the array to fill.

Returns

the number of elements written to the array

Note

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

@deprecatedOverriding("This should always forward to the 3-arg version of this method", since = "2.13.4")

Copy elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with values of this collection.

Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.

Type Params

B: the type of the elements of the array.

Value Params

start: the starting index of xs.
xs: the array to fill.

Returns

the number of elements written to the array

Note

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

Copy elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with at most len elements of this collection.

Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached, or len elements have been copied.

Type Params

B: the type of the elements of the array.

Value Params

len: the maximal number of elements to copy.
start: the starting index of xs.
xs: the array to fill.

Returns

the number of elements written to the array

Note

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.

Note: will not terminate for infinite-sized collections.

Type Params

B: the type of the elements of that

Value Params

p: the test predicate, which relates elements from both collections
that: the other collection

Returns

true if both collections have the same length and p(x, y) is true for all corresponding elements x of this iterator and y of that, otherwise false

Counts the number of elements in the collection which satisfy a predicate.

Note: will not terminate for infinite-sized collections.

Value Params

p: the predicate used to test elements.

Returns

the number of elements satisfying the predicate p.

Tests whether a predicate holds for at least one element of this collection.

Note: may not terminate for infinite-sized collections.

Value Params

p: the predicate used to test elements.

Returns

true if the given predicate p is satisfied by at least one element of this collection, otherwise false

Finds the first element of the collection satisfying a predicate, if any.

Note: may not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value Params

p: the predicate used to test elements.

Returns

an option value containing the first element in the collection that satisfies p, or None if none exists.

Folds the elements of this collection using the specified associative binary operator.

Folds the elements of this collection using the specified associative binary operator. The default implementation in IterableOnce is equivalent to foldLeft but may be overridden for more efficient traversal orders.

The order in which operations are performed on elements is unspecified and may be nondeterministic.

Note: will not terminate for infinite-sized collections.

Type Params

A1: a type parameter for the binary operator, a supertype of A.

Value Params

op: a binary operator that must be associative.
z: a neutral element for the fold operation; may be added to the result an arbitrary number of times, and must not change the result (e.g., Nil for list concatenation, 0 for addition, or 1 for multiplication).

Returns

the result of applying the fold operator op between all the elements and z, or z if this collection is empty.

Applies a binary operator to a start value and all elements of this collection, going left to right.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

Type Params

B: the result type of the binary operator.

Value Params

op: the binary operator.
z: the start value.

Returns

the result of inserting op between consecutive elements of this collection, going left to right with the start value z on the left: op(...op(z, x1), x2, ..., xn) where x1, ..., xn are the elements of this collection. Returns z if this collection is empty.

Applies a binary operator to all elements of this collection and a start value, going right to left.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

Type Params

B: the result type of the binary operator.

Value Params

op: the binary operator.
z: the start value.

Returns

the result of inserting op between consecutive elements of this collection, going right to left with the start value z on the right: op(x1, op(x2, ... op(xn, z)...)) where x1, ..., xn are the elements of this collection. Returns z if this collection is empty.

Tests whether a predicate holds for all elements of this collection.

Note: may not terminate for infinite-sized collections.

Value Params

p: the predicate used to test elements.

Returns

true if this collection is empty or the given predicate p holds for all elements of this collection, otherwise false.

Apply f to each element for its side effects Note: [U] parameter needed to help scalac's type inference.

Tests whether the collection is empty.

Note: Implementations in subclasses that are not repeatedly traversable must take care not to consume any elements when isEmpty is called.

Returns: true if the collection contains no elements, false otherwise.

Tests whether this collection can be repeatedly traversed.

Tests whether this collection can be repeatedly traversed. Always true for Iterables and false for Iterators unless overridden.

Returns: true if it is repeatedly traversable, false otherwise.

Finds the largest element.

Note: will not terminate for infinite-sized collections.

Type Params

B: The type over which the ordering is defined.

Value Params

ord: An ordering to be used for comparing elements.

Returns

the largest element of this collection with respect to the ordering ord.

Throws

UnsupportedOperationException: if this collection is empty.

Finds the first element which yields the largest value measured by function f.

Note: will not terminate for infinite-sized collections.

Type Params

B: The result type of the function f.

Value Params

cmp: An ordering to be used for comparing elements.
f: The measuring function.

Returns

the first element of this collection with the largest value measured by function f with respect to the ordering cmp.

Throws

UnsupportedOperationException: if this collection is empty.

Finds the first element which yields the largest value measured by function f.

Note: will not terminate for infinite-sized collections.

Type Params

B: The result type of the function f.

Value Params

cmp: An ordering to be used for comparing elements.
f: The measuring function.

Returns

an option value containing the first element of this collection with the largest value measured by function f with respect to the ordering cmp.

Finds the largest element.

Note: will not terminate for infinite-sized collections.

Type Params

B: The type over which the ordering is defined.

Value Params

ord: An ordering to be used for comparing elements.

Returns

an option value containing the largest element of this collection with respect to the ordering ord.

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

Type Params

B: The type over which the ordering is defined.

Value Params

ord: An ordering to be used for comparing elements.

Returns

the smallest element of this collection with respect to the ordering ord.

Throws

UnsupportedOperationException: if this collection is empty.

Finds the first element which yields the smallest value measured by function f.

Note: will not terminate for infinite-sized collections.

Type Params

B: The result type of the function f.

Value Params

cmp: An ordering to be used for comparing elements.
f: The measuring function.

Returns

the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.

Throws

UnsupportedOperationException: if this collection is empty.

Finds the first element which yields the smallest value measured by function f.

Note: will not terminate for infinite-sized collections.

Type Params

B: The result type of the function f.

Value Params

cmp: An ordering to be used for comparing elements.
f: The measuring function.

Returns

an option value containing the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

Type Params

B: The type over which the ordering is defined.

Value Params

ord: An ordering to be used for comparing elements.

Returns

an option value containing the smallest element of this collection with respect to the ordering ord.

Displays all elements of this collection in a string using start, end, and separator strings.

Delegates to addString, which can be overridden.

Value Params

end: the ending string.
sep: the separator string.
start: the starting string.

Returns

a string representation of this collection. The resulting string begins with the string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.

Example

List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"

@inline

Displays all elements of this collection in a string using a separator string.

Delegates to addString, which can be overridden.

Value Params

sep: the separator string.

Returns

a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.

Example

List(1, 2, 3).mkString("|") = "1|2|3"

@inline

Displays all elements of this collection in a string.

Delegates to addString, which can be overridden.

Returns: a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this collection follow each other without any separator string.

@deprecatedOverriding("nonEmpty is defined as !isEmpty; override isEmpty instead", "2.13.0")

Tests whether the collection is not empty.

Returns: true if the collection contains at least one element, false otherwise.

Multiplies up the elements of this collection.

Note: will not terminate for infinite-sized collections.

Type Params

B: the result type of the * operator.

Value Params

num: an implicit parameter defining a set of numeric operations which includes the * operator to be used in forming the product.

Returns

the product of all elements of this collection with respect to the * operator in num.

Reduces the elements of this collection using the specified associative binary operator.

The order in which operations are performed on elements is unspecified and may be nondeterministic.

Type Params

B: A type parameter for the binary operator, a supertype of A.

Value Params

op: A binary operator that must be associative.

Returns

The result of applying reduce operator op between all the elements if the collection is nonempty.

Throws

UnsupportedOperationException: if this collection is empty.

Applies a binary operator to all elements of this collection, going left to right.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

Type Params

B: the result type of the binary operator.

Value Params

op: the binary operator.

Returns

the result of inserting op between consecutive elements of this collection, going left to right: op( op( ... op(x1, x2) ..., xn-1), xn) where x1, ..., xn are the elements of this collection.

Throws

UnsupportedOperationException: if this collection is empty.

Optionally applies a binary operator to all elements of this collection, going left to right.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

Type Params

B: the result type of the binary operator.

Value Params

op: the binary operator.

Returns

an option value containing the result of reduceLeft(op) if this collection is nonempty, None otherwise.

Reduces the elements of this collection, if any, using the specified associative binary operator.

The order in which operations are performed on elements is unspecified and may be nondeterministic.

Type Params

B: A type parameter for the binary operator, a supertype of A.

Value Params

op: A binary operator that must be associative.

Returns

An option value containing result of applying reduce operator op between all the elements if the collection is nonempty, and None otherwise.

Applies a binary operator to all elements of this collection, going right to left.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

Type Params

B: the result type of the binary operator.

Value Params

op: the binary operator.

Returns

the result of inserting op between consecutive elements of this collection, going right to left: op(x1, op(x2, ..., op(xn-1, xn)...)) where x1, ..., xn are the elements of this collection.

Throws

UnsupportedOperationException: if this collection is empty.

Optionally applies a binary operator to all elements of this collection, going right to left.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

Type Params

B: the result type of the binary operator.

Value Params

op: the binary operator.

Returns

an option value containing the result of reduceRight(op) if this collection is nonempty, None otherwise.

The size of this collection.

Note: will not terminate for infinite-sized collections.

Returns: the number of elements in this collection.

Splits this collection into a prefix/suffix pair at a given position.

Note: c splitAt n is equivalent to (but possibly more efficient than) (c take n, c drop n).

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value Params

n: the position at which to split.

Returns

a pair of collections consisting of the first n elements of this collection, and the other elements.

Sums up the elements of this collection.

Note: will not terminate for infinite-sized collections.

Type Params

B: the result type of the + operator.

Value Params

num: an implicit parameter defining a set of numeric operations which includes the + operator to be used in forming the sum.

Returns

the sum of all elements of this collection with respect to the + operator in num.

Given a collection factory factory, convert this collection to the appropriate representation for the current element type A.

Given a collection factory factory, convert this collection to the appropriate representation for the current element type A. Example uses:

xs.to(List) xs.to(ArrayBuffer) xs.to(BitSet) // for xs: Iterable[Int]

Convert collection to array.

Implementation note: DO NOT call Array.from from this method.

@inline

Returns: This collection as a Seq[A]. This is equivalent to to(Seq) but might be faster.

Deprecated methods

@deprecated("Use foldLeft instead of /:", "2.13.0") @inline

Deprecated

@deprecated("Use foldRight instead of :\\", "2.13.0") @inline

Deprecated

@deprecated("`aggregate` is not relevant for sequential collections. Use `foldLeft(z)(seqop)` instead.", "2.13.0")

Deprecated

@deprecated("Use `dest ++= coll` instead", "2.13.0") @inline

Deprecated

@deprecated("Check .knownSize instead of .hasDefiniteSize for more actionable information (see scaladoc for details)", "2.13.0")

Tests whether this collection is known to have a finite size.

Tests whether this collection is known to have a finite size. All strict collections are known to have finite size. For a non-strict collection such as Stream, the predicate returns true if all elements have been computed. It returns false if the stream is not yet evaluated to the end. Non-empty Iterators usually return false even if they were created from a collection with a known finite size.

Note: many collection methods will not work on collections of infinite sizes. The typical failure mode is an infinite loop. These methods always attempt a traversal without checking first that hasDefiniteSize returns true. However, checking hasDefiniteSize can provide an assurance that size is well-defined and non-termination is not a concern.

Returns: true if this collection is known to have finite size, false otherwise.
See also: method knownSize for a more useful alternative
Deprecated: This method is deprecated in 2.13 because it does not provide any actionable information. As noted above, even the collection library itself does not use it. When there is no guarantee that a collection is finite, it is generally best to attempt a computation anyway and document that it will not terminate for infinite collections rather than backing out because this would prevent performing the computation on collections that are in fact finite even though hasDefiniteSize returns false.

@deprecated("Use .iterator instead of .toIterator", "2.13.0") @inline

Deprecated

@deprecated("Use .to(LazyList) instead of .toStream", "2.13.0") @inline

Deprecated