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/Scala 2.12 Library

Class scala.collection.immutable.::

final case class ::[B](head: B, tl: List[B]) extends List[B] with Product with Serializable

A non empty list characterized by a head and a tail.

B

the type of the list elements.

head

the first element of the list

tl

the list containing the remaining elements of this list after the first one.

Annotations
@SerialVersionUID()
Source
List.scala
Since

2.8

Linear Supertypes

Instance Constructors

new ::(head: B, tl: List[B])

head

the first element of the list

tl

the list containing the remaining elements of this list after the first one.

Type Members

class WithFilter extends FilterMonadic[A, Repr]

A class supporting filtered operations. Instances of this class are returned by method withFilter.

Definition Classes
TraversableLike

type Self = List[B]

The type implementing this traversable

Attributes
protected[this]
Definition Classes
TraversableLike

Value Members

final def !=(arg0: Any): Boolean

Test two objects for inequality.

returns

true if !(this == that), false otherwise.

Definition Classes
AnyRef → Any

final def ##(): Int

Equivalent to x.hashCode except for boxed numeric types and null. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For null returns a hashcode where null.hashCode throws a NullPointerException.

returns

a hash value consistent with ==

Definition Classes
AnyRef → Any

def +(other: String): String

Implicit
This member is added by an implicit conversion from ::[B] to any2stringadd[::[B]] performed by method any2stringadd in scala.Predef.
Definition Classes
any2stringadd

def ++[B >: B, That](that: GenTraversableOnce[B])(implicit bf: CanBuildFrom[List[B], B, That]): That

Returns a new list containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the list is the most specific superclass encompassing the element types of the two operands.

B

the element type of the returned collection.

That

the class of the returned collection. In the standard library configuration, That is always List[B] because an implicit of type CanBuildFrom[List, B, That] is defined in object List.

that

the traversable to append.

bf

an implicit value of class CanBuildFrom which determines the result class That from the current representation type Repr and the new element type B. This is usually the canBuildFrom value defined in object List.

returns

a new collection of type That which contains all elements of this list followed by all elements of that.

Definition Classes
ListTraversableLikeGenTraversableLike

def ++:[B >: B, That](that: collection.Traversable[B])(implicit bf: CanBuildFrom[List[B], B, That]): That

As with ++, returns a new collection containing the elements from the left operand followed by the elements from the right operand.

It differs from ++ in that the right operand determines the type of the resulting collection rather than the left one. Mnemonic: the COLon is on the side of the new COLlection type.

Example:

scala> val x = List(1)
x: List[Int] = List(1)

scala> val y = LinkedList(2)
y: scala.collection.mutable.LinkedList[Int] = LinkedList(2)

scala> val z = x ++: y
z: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2)

This overload exists because: for the implementation of ++: we should reuse that of ++ because many collections override it with more efficient versions.

Since TraversableOnce has no ++ method, we have to implement that directly, but Traversable and down can use the overload.

B

the element type of the returned collection.

That

the class of the returned collection. Where possible, That is the same class as the current collection class Repr, but this depends on the element type B being admissible for that class, which means that an implicit instance of type CanBuildFrom[Repr, B, That] is found.

that

the traversable to append.

bf

an implicit value of class CanBuildFrom which determines the result class That from the current representation type Repr and the new element type B.

returns

a new collection of type That which contains all elements of this traversable collection followed by all elements of that.

Definition Classes
TraversableLike

def ++:[B](that: TraversableOnce[B]): List[B]

[use case]

As with ++, returns a new collection containing the elements from the left operand followed by the elements from the right operand.

It differs from ++ in that the right operand determines the type of the resulting collection rather than the left one. Mnemonic: the COLon is on the side of the new COLlection type.

Example:

scala> val x = List(1)
x: List[Int] = List(1)

scala> val y = LinkedList(2)
y: scala.collection.mutable.LinkedList[Int] = LinkedList(2)

scala> val z = x ++: y
z: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2)
B

the element type of the returned collection.

that

the traversable to append.

returns

a new list which contains all elements of this list followed by all elements of that.

Definition Classes
TraversableLike
Full Signature

def +:(elem: A): List[A]

[use case]

A copy of the list with an element prepended.

Note that :-ending operators are right associative (see example). A mnemonic for +: vs. :+ is: the COLon goes on the COLlection side.

Also, the original list is not modified, so you will want to capture the result.

Example:

scala> val x = List(1)
x: List[Int] = List(1)

scala> val y = 2 +: x
y: List[Int] = List(2, 1)

scala> println(x)
List(1)
elem

the prepended element

returns

a new list consisting of elem followed by all elements of this list.

Definition Classes
ListSeqLikeGenSeqLike
Full Signature

def ->[B](y: B): (::[B], B)

Implicit
This member is added by an implicit conversion from ::[B] to ArrowAssoc[::[B]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc
Annotations
@inline()

def /:[B](z: B)(op: (B, B) ⇒ B): B

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

Note: /: is alternate syntax for foldLeft; z /: xs is the same as xs foldLeft z.

Examples:

Note that the folding function used to compute b is equivalent to that used to compute c.

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

scala> val b = (5 /: a)(_+_)
b: Int = 15

scala> val c = (5 /: a)((x,y) => x + y)
c: Int = 15

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.

B

the result type of the binary operator.

z

the start value.

op

the binary operator.

returns

the result of inserting op between consecutive elements of this traversable or iterator, going left to right with the start value z on the left:

op(...op(op(z, x_1), x_2), ..., x_n)

where x1, ..., xn are the elements of this traversable or iterator.

Definition Classes
TraversableOnceGenTraversableOnce

def :+(elem: A): List[A]

[use case]

A copy of this list with an element appended.

A mnemonic for +: vs. :+ is: the COLon goes on the COLlection side.

Example:

scala> val a = List(1)
a: List[Int] = List(1)

scala> val b = a :+ 2
b: List[Int] = List(1, 2)

scala> println(a)
List(1)
elem

the appended element

returns

a new list consisting of all elements of this list followed by elem.

Definition Classes
SeqLikeGenSeqLike
Full Signature

def ::(x: B): List[B]

[use case]

Adds an element at the beginning of this list.

Example:

1 :: List(2, 3) = List(2, 3).::(1) = List(1, 2, 3)
x

the element to prepend.

returns

a list which contains x as first element and which continues with this list.

Definition Classes
List
Full Signature

def :::(prefix: List[B]): List[B]

[use case]

Adds the elements of a given list in front of this list.

Example:

List(1, 2) ::: List(3, 4) = List(3, 4).:::(List(1, 2)) = List(1, 2, 3, 4)
prefix

The list elements to prepend.

returns

a list resulting from the concatenation of the given list prefix and this list.

Definition Classes
List
Full Signature

def :\[B](z: B)(op: (B, B) ⇒ B): B

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

Note: :\ is alternate syntax for foldRight; xs :\ z is the same as xs foldRight z.

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.

Examples:

Note that the folding function used to compute b is equivalent to that used to compute c.

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

scala> val b = (a :\ 5)(_+_)
b: Int = 15

scala> val c = (a :\ 5)((x,y) => x + y)
c: Int = 15
B

the result type of the binary operator.

z

the start value

op

the binary operator

returns

the result of inserting op between consecutive elements of this traversable or iterator, going right to left with the start value z on the right:

op(x_1, op(x_2, ... op(x_n, z)...))

where x1, ..., xn are the elements of this traversable or iterator.

Definition Classes
TraversableOnceGenTraversableOnce

final def ==(arg0: Any): Boolean

The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).

returns

true if the receiver object is equivalent to the argument; false otherwise.

Definition Classes
AnyRef → Any

def addString(b: StringBuilder): StringBuilder

Appends all elements of this traversable or iterator to a string builder. The written text consists of the string representations (w.r.t. the method toString) of all elements of this traversable or iterator 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
b

the string builder to which elements are appended.

returns

the string builder b to which elements were appended.

Definition Classes
TraversableOnce

def addString(b: StringBuilder, sep: String): StringBuilder

Appends all elements of this traversable or iterator 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 traversable or iterator, 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
b

the string builder to which elements are appended.

sep

the separator string.

returns

the string builder b to which elements were appended.

Definition Classes
TraversableOnce

def addString(b: StringBuilder, start: String, sep: String, end: String): StringBuilder

Appends all elements of this traversable or iterator 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 traversable or iterator 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)
b

the string builder to which elements are appended.

start

the starting string.

sep

the separator string.

end

the ending string.

returns

the string builder b to which elements were appended.

Definition Classes
TraversableOnce

def aggregate[B](z: ⇒ B)(seqop: (B, B) ⇒ B, combop: (B, B) ⇒ B): B

Aggregates the results of applying an operator to subsequent elements.

This is a more general form of fold and reduce. It is similar to foldLeft in that it doesn't require the result to be a supertype of the element type. In addition, it allows parallel collections to be processed in chunks, and then combines the intermediate results.

aggregate splits the traversable or iterator into partitions and processes each partition by sequentially applying seqop, starting with z (like foldLeft). Those intermediate results are then combined by using combop (like fold). The implementation of this operation may operate on an arbitrary number of collection partitions (even 1), so combop may be invoked an arbitrary number of times (even 0).

As an example, consider summing up the integer values of a list of chars. The initial value for the sum is 0. First, seqop transforms each input character to an Int and adds it to the sum (of the partition). Then, combop just needs to sum up the intermediate results of the partitions:

List('a', 'b', 'c').aggregate(0)({ (sum, ch) => sum + ch.toInt }, { (p1, p2) => p1 + p2 })
B

the type of accumulated results

z

the initial value for the accumulated result of the partition - this will typically be the neutral element for the seqop operator (e.g. Nil for list concatenation or 0 for summation) and may be evaluated more than once

seqop

an operator used to accumulate results within a partition

combop

an associative operator used to combine results from different partitions

Definition Classes
TraversableOnceGenTraversableOnce

def andThen[C](k: (B) ⇒ C): PartialFunction[Int, C]

Composes this partial function with a transformation function that gets applied to results of this partial function.

C

the result type of the transformation function.

k

the transformation function

returns

a partial function with the same domain as this partial function, which maps arguments x to k(this(x)).

Definition Classes
PartialFunctionFunction1

def apply(n: Int): B

Selects an element by its index in the sequence. Note: the execution of apply may take time proportional to the index value.

returns

the element of this sequence at index idx, where 0 indicates the first element.

Definition Classes
LinearSeqOptimizedSeqLikeGenSeqLike
Exceptions thrown

IndexOutOfBoundsException if idx does not satisfy 0 <= idx < length.

def applyOrElse[A1 <: Int, B1 >: B](x: A1, default: (A1) ⇒ B1): B1

Applies this partial function to the given argument when it is contained in the function domain. Applies fallback function where this partial function is not defined.

Note that expression pf.applyOrElse(x, default) is equivalent to

if(pf isDefinedAt x) pf(x) else default(x)

except that applyOrElse method can be implemented more efficiently. For all partial function literals the compiler generates an applyOrElse implementation which avoids double evaluation of pattern matchers and guards. This makes applyOrElse the basis for the efficient implementation for many operations and scenarios, such as:

    combining partial functions into orElse/andThen chains does not lead to excessive apply/isDefinedAt evaluation lift and unlift do not evaluate source functions twice on each invocation runWith allows efficient imperative-style combining of partial functions with conditionally applied actions

For non-literal partial function classes with nontrivial isDefinedAt method it is recommended to override applyOrElse with custom implementation that avoids double isDefinedAt evaluation. This may result in better performance and more predictable behavior w.r.t. side effects.

x

the function argument

default

the fallback function

returns

the result of this function or fallback function application.

Definition Classes
PartialFunction
Since

2.10

final def asInstanceOf[T0]: T0

Cast the receiver object to be of type T0.

Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression 1.asInstanceOf[String] will throw a ClassCastException at runtime, while the expression List(1).asInstanceOf[List[String]] will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.

returns

the receiver object.

Definition Classes
Any
Exceptions thrown

ClassCastException if the receiver object is not an instance of the erasure of type T0.

def canEqual(that: Any): Boolean

Method called from equality methods, so that user-defined subclasses can refuse to be equal to other collections of the same kind.

that

The object with which this iterable collection should be compared

returns

true, if this iterable collection can possibly equal that, false otherwise. The test takes into consideration only the run-time types of objects but ignores their elements.

Definition Classes
IterableLikeEquals

def clone(): AnyRef

Create a copy of the receiver object.

The default implementation of the clone method is platform dependent.

returns

a copy of the receiver object.

Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws( ... ) @native()
Note

not specified by SLS as a member of AnyRef

final def collect[B](pf: PartialFunction[A, B]): List[B]

[use case]

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

B

the element type of the returned collection.

pf

the partial function which filters and maps the list.

returns

a new list 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.

Definition Classes
ListTraversableLikeGenTraversableLike
Full Signature

def collectFirst[B](pf: PartialFunction[B, B]): Option[B]

Finds the first element of the traversable or iterator 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.

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.

Definition Classes
TraversableOnce
Example:

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

def combinations(n: Int): Iterator[List[B]]

Iterates over combinations. A _combination_ of length n is a subsequence of the original sequence, with the elements taken in order. Thus, "xy" and "yy" are both length-2 combinations of "xyy", but "yx" is not. If there is more than one way to generate the same subsequence, only one will be returned.

For example, "xyyy" has three different ways to generate "xy" depending on whether the first, second, or third "y" is selected. However, since all are identical, only one will be chosen. Which of the three will be taken is an implementation detail that is not defined.

returns

An Iterator which traverses the possible n-element combinations of this sequence.

Definition Classes
SeqLike
Example:

    "abbbc".combinations(2) = Iterator(ab, ac, bb, bc)

def companion: GenericCompanion[List]

The factory companion object that builds instances of class List. (or its Iterable superclass where class List is not a Seq.)

Definition Classes
ListLinearSeqLinearSeqSeqIterableTraversableSeqGenSeqIterableGenIterableTraversableGenTraversableGenericTraversableTemplate

def compose[A](g: (A) ⇒ Int): (A) ⇒ B

Composes two instances of Function1 in a new Function1, with this function applied last.

A

the type to which function g can be applied

g

a function A => T1

returns

a new function f such that f(x) == apply(g(x))

Definition Classes
Function1
Annotations
@unspecialized()

def contains[A1 >: B](elem: A1): Boolean

Tests whether this sequence contains a given value as an element.

Note: may not terminate for infinite-sized collections.

elem

the element to test.

returns

true if this sequence has an element that is equal (as determined by ==) to elem, false otherwise.

Definition Classes
LinearSeqOptimizedSeqLike

def containsSlice[B](that: GenSeq[B]): Boolean

Tests whether this sequence contains a given sequence as a slice.

Note: may not terminate for infinite-sized collections.

that

the sequence to test

returns

true if this sequence contains a slice with the same elements as that, otherwise false.

Definition Classes
SeqLike

def copyToArray(xs: Array[A], start: Int, len: Int): Unit

[use case]

Copies the elements of this list to an array. Fills the given array xs with at most len elements of this list, starting at position start. Copying will stop once either the end of the current list is reached, or the end of the target array is reached, or len elements have been copied.

xs

the array to fill.

start

the starting index.

len

the maximal number of elements to copy.

Definition Classes
IterableLikeTraversableLikeTraversableOnceGenTraversableOnce
Full Signature

def copyToArray(xs: Array[A]): Unit

[use case]

Copies the elements of this list to an array. Fills the given array xs with values of this list. Copying will stop once either the end of the current list is reached, or the end of the target array is reached.

xs

the array to fill.

Definition Classes
TraversableOnceGenTraversableOnce
Full Signature

def copyToArray(xs: Array[A], start: Int): Unit

[use case]

Copies the elements of this list to an array. Fills the given array xs with values of this list, beginning at index start. Copying will stop once either the end of the current list is reached, or the end of the target array is reached.

xs

the array to fill.

start

the starting index.

Definition Classes
TraversableOnceGenTraversableOnce
Full Signature

def copyToBuffer[B >: B](dest: Buffer[B]): Unit

Copies all elements of this traversable or iterator to a buffer.

Note: will not terminate for infinite-sized collections.

dest

The buffer to which elements are copied.

Definition Classes
TraversableOnce

final def corresponds[B](that: GenSeq[B])(p: (B, B) ⇒ Boolean): Boolean

Tests whether every element of this sequence relates to the corresponding element of another sequence by satisfying a test predicate.

B

the type of the elements of that

that

the other sequence

p

the test predicate, which relates elements from both sequences

returns

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

Definition Classes
LinearSeqLikeSeqLikeGenSeqLike
Annotations
@tailrec()

def count(p: (B) ⇒ Boolean): Int

Counts the number of elements in the traversable or iterator which satisfy a predicate.

p

the predicate used to test elements.

returns

the number of elements satisfying the predicate p.

Definition Classes
TraversableOnceGenTraversableOnce

def diff(that: collection.Seq[B]): List[B]

[use case]

Computes the multiset difference between this list and another sequence.

that

the sequence of elements to remove

returns

a new list which contains all elements of this list except some of occurrences of elements that also appear in that. If an element value x appears n times in that, then the first n occurrences of x will not form part of the result, but any following occurrences will.

Definition Classes
SeqLikeGenSeqLike
Full Signature

def distinct: List[B]

Builds a new sequence from this sequence without any duplicate elements.

Note: will not terminate for infinite-sized collections.

returns

A new sequence which contains the first occurrence of every element of this sequence.

Definition Classes
SeqLikeGenSeqLike

def drop(n: Int): List[B]

Selects all elements except first n ones.

n

the number of elements to drop from this list.

returns

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

Definition Classes
ListLinearSeqOptimizedIterableLikeTraversableLikeGenTraversableLike

def dropRight(n: Int): List[B]

Selects all elements except last n ones.

n

The number of elements to take

returns

a sequence consisting of all elements of this sequence except the last n ones, or else the empty sequence, if this sequence has less than n elements.

Definition Classes
LinearSeqOptimizedIterableLike

final def dropWhile(p: (B) ⇒ Boolean): List[B]

Drops longest prefix of elements that satisfy a predicate.

returns

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

Definition Classes
ListTraversableLikeGenTraversableLike
Annotations
@inline()

def endsWith[B](that: GenSeq[B]): Boolean

Tests whether this sequence ends with the given sequence.

Note: will not terminate for infinite-sized collections.

that

the sequence to test

returns

true if this sequence has that as a suffix, false otherwise.

Definition Classes
SeqLikeGenSeqLike

def ensuring(cond: (::[B]) ⇒ Boolean, msg: ⇒ Any): ::[B]

Implicit
This member is added by an implicit conversion from ::[B] to Ensuring[::[B]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring

def ensuring(cond: (::[B]) ⇒ Boolean): ::[B]

Implicit
This member is added by an implicit conversion from ::[B] to Ensuring[::[B]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring

def ensuring(cond: Boolean, msg: ⇒ Any): ::[B]

Implicit
This member is added by an implicit conversion from ::[B] to Ensuring[::[B]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring

def ensuring(cond: Boolean): ::[B]

Implicit
This member is added by an implicit conversion from ::[B] to Ensuring[::[B]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring

final def eq(arg0: AnyRef): Boolean

Tests whether the argument (that) is a reference to the receiver object (this).

The eq method implements an equivalence relation on non-null instances of AnyRef, and has three additional properties:

    It is consistent: for any non-null instances x and y of type AnyRef, multiple invocations of x.eq(y) consistently returns true or consistently returns false.For any non-null instance x of type AnyRef, x.eq(null) and null.eq(x) returns false. null.eq(null) returns true.

When overriding the equals or hashCode methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2), they should be equal to each other (o1 == o2) and they should hash to the same value (o1.hashCode == o2.hashCode).

returns

true if the argument is a reference to the receiver object; false otherwise.

Definition Classes
AnyRef

def equals(that: Any): Boolean

The equals method for arbitrary sequences. Compares this sequence to some other object.

that

The object to compare the sequence to

returns

true if that is a sequence that has the same elements as this sequence in the same order, false otherwise

Definition Classes
GenSeqLikeEqualsAny

def exists(p: (B) ⇒ Boolean): Boolean

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

Note: may not terminate for infinite-sized collections.

p

the predicate used to test elements.

returns

false if this sequence is empty, otherwise true if the given predicate p holds for some of the elements of this sequence, otherwise false

Definition Classes
LinearSeqOptimizedIterableLikeTraversableLikeTraversableOnceGenTraversableOnce

def filter(p: (B) ⇒ Boolean): List[B]

Selects all elements of this traversable collection which satisfy a predicate.

p

the predicate used to test elements.

returns

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

Definition Classes
TraversableLikeGenTraversableLike

def filterNot(p: (B) ⇒ Boolean): List[B]

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

p

the predicate used to test elements.

returns

a new traversable collection consisting of all elements of this traversable collection that do not satisfy the given predicate p. The order of the elements is preserved.

Definition Classes
TraversableLikeGenTraversableLike

def finalize(): Unit

Called by the garbage collector on the receiver object when there are no more references to the object.

The details of when and if the finalize method is invoked, as well as the interaction between finalize and non-local returns and exceptions, are all platform dependent.

Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws( classOf[java.lang.Throwable] )
Note

not specified by SLS as a member of AnyRef

def find(p: (B) ⇒ Boolean): Option[B]

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

Note: may not terminate for infinite-sized collections.

p

the predicate used to test elements.

returns

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

Definition Classes
LinearSeqOptimizedIterableLikeTraversableLikeTraversableOnceGenTraversableOnce

final def flatMap[B](f: (A) ⇒ GenTraversableOnce[B]): List[B]

[use case]

Builds a new collection by applying a function to all elements of this list 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 list. 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 => 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)
B

the element type of the returned collection.

f

the function to apply to each element.

returns

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

Definition Classes
ListTraversableLikeGenTraversableLikeFilterMonadic
Full Signature

def flatten[B]: List[B]

[use case]

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

The resulting collection's type will be guided by the static type of list. 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)
B

the type of the elements of each traversable collection.

returns

a new list resulting from concatenating all element lists.

Definition Classes
GenericTraversableTemplate
Full Signature

def fold[A1 >: B](z: A1)(op: (A1, A1) ⇒ A1): A1

Folds the elements of this traversable or iterator using the specified associative binary operator.

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

Note: will not terminate for infinite-sized collections.

A1

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

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).

op

a binary operator that must be associative.

returns

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

Definition Classes
TraversableOnceGenTraversableOnce

def foldLeft[B](z: B)(op: (B, B) ⇒ B): B

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

Note: will not terminate for infinite-sized collections.

B

the result type of the binary operator.

z

the start value.

op

the binary operator.

returns

the result of inserting op between consecutive elements of this sequence, going left to right with the start value z on the left:

op(...op(z, x_1), x_2, ..., x_n)

where x1, ..., xn are the elements of this sequence. Returns z if this sequence is empty.

Definition Classes
LinearSeqOptimizedTraversableOnceGenTraversableOnce

def foldRight[B](z: B)(op: (B, B) ⇒ B): B

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

B

the result type of the binary operator.

z

the start value.

op

the binary operator.

returns

the result of inserting op between consecutive elements of this list, going right to left with the start value z on the right:

op(x_1, op(x_2, ... op(x_n, z)...))

where x1, ..., xn are the elements of this list. Returns z if this list is empty.

Definition Classes
ListLinearSeqOptimizedIterableLikeTraversableOnceGenTraversableOnce

def forall(p: (B) ⇒ Boolean): Boolean

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

Note: may not terminate for infinite-sized collections.

p

the predicate used to test elements.

returns

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

Definition Classes
LinearSeqOptimizedIterableLikeTraversableLikeTraversableOnceGenTraversableOnce

final def foreach(f: (A) ⇒ Unit): Unit

[use case]

Applies a function f to all elements of this list.

Note: this method underlies the implementation of most other bulk operations. Subclasses should re-implement this method if a more efficient implementation exists.

f

the function that is applied for its side-effect to every element. The result of function f is discarded.

Definition Classes
ListLinearSeqOptimizedIterableLikeGenericTraversableTemplateTraversableLikeGenTraversableLikeTraversableOnceGenTraversableOnceFilterMonadic
Full Signature

def formatted(fmtstr: String): String

Returns string formatted according to given format string. Format strings are as for String.format (@see java.lang.String.format).

Implicit
This member is added by an implicit conversion from ::[B] to StringFormat[::[B]] performed by method StringFormat in scala.Predef.
Definition Classes
StringFormat
Annotations
@inline()

def genericBuilder[B]: Builder[B, List[B]]

The generic builder that builds instances of Traversable at arbitrary element types.

Definition Classes
GenericTraversableTemplate

final def getClass(): Class[_]

Returns the runtime class representation of the object.

returns

a class object corresponding to the runtime type of the receiver.

Definition Classes
AnyRef → Any
Annotations
@native()

def groupBy[K](f: (B) ⇒ K): Map[K, List[B]]

Partitions this traversable collection into a map of traversable collections according to some discriminator function.

Note: this method is not re-implemented by views. This means when applied to a view it will always force the view and return a new traversable collection.

K

the type of keys returned by the discriminator function.

f

the discriminator function.

returns

A map from keys to traversable collections such that the following invariant holds:

(xs groupBy f)(k) = xs filter (x => f(x) == k)

That is, every key k is bound to a traversable collection of those elements x for which f(x) equals k.

Definition Classes
TraversableLikeGenTraversableLike

def grouped(size: Int): Iterator[List[B]]

Partitions elements in fixed size iterable collections.

size

the number of elements per group

returns

An iterator producing iterable collections of size size, except the last will be less than size size if the elements don't divide evenly.

Definition Classes
IterableLike
See also

scala.collection.Iterator, method grouped

def hasDefiniteSize: Boolean

Tests whether this traversable 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.

Definition Classes
TraversableLikeTraversableOnceGenTraversableOnce

def hashCode(): Int

Hashcodes for Seq produce a value from the hashcodes of all the elements of the sequence.

returns

the hash code value for this object.

Definition Classes
LinearSeqLikeGenSeqLike → AnyRef → Any

Selects the first element of this list.

returns

the first element of this list.

Definition Classes
::ListLinearSeqOptimizedIterableLikeGenericTraversableTemplateTraversableLikeGenTraversableLike
Exceptions thrown

NoSuchElementException if the list is empty.

def headOption: Option[B]

Optionally selects the first element.

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

returns

the first element of this traversable collection if it is nonempty, None if it is empty.

Definition Classes
TraversableLikeGenTraversableLike

def indexOf(elem: B, from: Int): Int

[use case]

Finds index of first occurrence of some value in this list after or at some start index.

elem

the element value to search for.

from

the start index

returns

the index >= from of the first element of this list that is equal (as determined by ==) to elem, or -1, if none exists.

Definition Classes
GenSeqLike
Full Signature

def indexOf(elem: B): Int

[use case]

Finds index of first occurrence of some value in this list.

elem

the element value to search for.

returns

the index of the first element of this list that is equal (as determined by ==) to elem, or -1, if none exists.

Definition Classes
GenSeqLike
Full Signature

def indexOfSlice[B >: B](that: GenSeq[B], from: Int): Int

Finds first index after or at a start index where this sequence contains a given sequence as a slice.

Note: may not terminate for infinite-sized collections.

that

the sequence to test

from

the start index

returns

the first index >= from such that the elements of this sequence starting at this index match the elements of sequence that, or -1 of no such subsequence exists.

Definition Classes
SeqLike

def indexOfSlice[B >: B](that: GenSeq[B]): Int

Finds first index where this sequence contains a given sequence as a slice.

Note: may not terminate for infinite-sized collections.

that

the sequence to test

returns

the first index such that the elements of this sequence starting at this index match the elements of sequence that, or -1 of no such subsequence exists.

Definition Classes
SeqLike

def indexWhere(p: (B) ⇒ Boolean, from: Int): Int

Finds index of the first element satisfying some predicate after or at some start index.

Note: may not terminate for infinite-sized collections.

p

the predicate used to test elements.

from

the start index

returns

the index >= from of the first element of this sequence that satisfies the predicate p, or -1, if none exists.

Definition Classes
LinearSeqOptimizedSeqLikeGenSeqLike

def indexWhere(p: (B) ⇒ Boolean): Int

Finds index of first element satisfying some predicate.

Note: may not terminate for infinite-sized collections.

p

the predicate used to test elements.

returns

the index of the first element of this general sequence that satisfies the predicate p, or -1, if none exists.

Definition Classes
GenSeqLike

def indices: Range

Produces the range of all indices of this sequence.

returns

a Range value from 0 to one less than the length of this sequence.

Definition Classes
SeqLike

def init: List[B]

Selects all elements except the last.

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

returns

a traversable collection consisting of all elements of this traversable collection except the last one.

Definition Classes
TraversableLikeGenTraversableLike
Exceptions thrown

UnsupportedOperationException if the traversable collection is empty.

def inits: Iterator[List[B]]

Iterates over the inits of this traversable collection. The first value will be this traversable collection and the final one will be an empty traversable collection, with the intervening values the results of successive applications of init.

returns

an iterator over all the inits of this traversable collection

Definition Classes
TraversableLike
Example:

    List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)

def intersect(that: collection.Seq[B]): List[B]

[use case]

Computes the multiset intersection between this list and another sequence.

that

the sequence of elements to intersect with.

returns

a new list which contains all elements of this list which also appear in that. If an element value x appears n times in that, then the first n occurrences of x will be retained in the result, but any following occurrences will be omitted.

Definition Classes
SeqLikeGenSeqLike
Full Signature

def isDefinedAt(x: Int): Boolean

Tests whether this sequence contains given index.

The implementations of methods apply and isDefinedAt turn a Seq[A] into a PartialFunction[Int, A].

returns

true if this sequence contains an element at position idx, false otherwise.

Definition Classes
LinearSeqOptimizedGenSeqLike

def isEmpty: Boolean

Tests whether the list 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 list contains no elements, false otherwise.

Definition Classes
::ListLinearSeqOptimizedSeqLikeIterableLikeGenericTraversableTemplateTraversableLikeTraversableOnceGenTraversableOnce

final def isInstanceOf[T0]: Boolean

Test whether the dynamic type of the receiver object is T0.

Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression 1.isInstanceOf[String] will return false, while the expression List(1).isInstanceOf[List[String]] will return true. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.

returns

true if the receiver object is an instance of erasure of type T0; false otherwise.

Definition Classes
Any

final def isTraversableAgain: Boolean

Tests whether this traversable collection can be repeatedly traversed.

returns

true

Definition Classes
TraversableLikeGenTraversableLikeGenTraversableOnce

def iterator: Iterator[B]

Creates a new iterator over all elements contained in this iterable object.

returns

the new iterator

Definition Classes
LinearSeqLikeIterableLikeGenIterableLike

def last: B

Selects the last element.

returns

The last element of this sequence.

Definition Classes
LinearSeqOptimizedTraversableLikeGenTraversableLike
Exceptions thrown

NoSuchElementException If the sequence is empty.

def lastIndexOf(elem: B, end: Int): Int

[use case]

Finds index of last occurrence of some value in this list before or at a given end index.

elem

the element value to search for.

end

the end index.

returns

the index <= end of the last element of this list that is equal (as determined by ==) to elem, or -1, if none exists.

Definition Classes
GenSeqLike
Full Signature

def lastIndexOf(elem: B): Int

[use case]

Finds index of last occurrence of some value in this list.

elem

the element value to search for.

returns

the index of the last element of this list that is equal (as determined by ==) to elem, or -1, if none exists.

Definition Classes
GenSeqLike
Full Signature

def lastIndexOfSlice[B >: B](that: GenSeq[B], end: Int): Int

Finds last index before or at a given end index where this sequence contains a given sequence as a slice.

that

the sequence to test

end

the end index

returns

the last index <= end such that the elements of this sequence starting at this index match the elements of sequence that, or -1 of no such subsequence exists.

Definition Classes
SeqLike

def lastIndexOfSlice[B >: B](that: GenSeq[B]): Int

Finds last index where this sequence contains a given sequence as a slice.

Note: will not terminate for infinite-sized collections.

that

the sequence to test

returns

the last index such that the elements of this sequence starting a this index match the elements of sequence that, or -1 of no such subsequence exists.

Definition Classes
SeqLike

def lastIndexWhere(p: (B) ⇒ Boolean, end: Int): Int

Finds index of last element satisfying some predicate before or at given end index.

p

the predicate used to test elements.

returns

the index <= end of the last element of this sequence that satisfies the predicate p, or -1, if none exists.

Definition Classes
LinearSeqOptimizedSeqLikeGenSeqLike

def lastIndexWhere(p: (B) ⇒ Boolean): Int

Finds index of last element satisfying some predicate.

Note: will not terminate for infinite-sized collections.

p

the predicate used to test elements.

returns

the index of the last element of this general sequence that satisfies the predicate p, or -1, if none exists.

Definition Classes
GenSeqLike

def lastOption: Option[B]

Optionally selects the last element.

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

returns

the last element of this traversable collection$ if it is nonempty, None if it is empty.

Definition Classes
TraversableLikeGenTraversableLike

def length: Int

The length of the sequence.

Note: will not terminate for infinite-sized collections.

Note: the execution of length may take time proportional to the length of the sequence.

returns

the number of elements in this sequence.

Definition Classes
LinearSeqOptimizedSeqLikeGenSeqLike

def lengthCompare(len: Int): Int

Compares the length of this sequence to a test value.

len

the test value that gets compared with the length.

returns

A value x where

x <  0       if this.length <  len
x == 0       if this.length == len
x >  0       if this.length >  len

The method as implemented here does not call length directly; its running time is O(length min len) instead of O(length). The method should be overwritten if computing length is cheap.

Definition Classes
LinearSeqOptimizedSeqLike

def lift: (Int) ⇒ Option[B]

Turns this partial function into a plain function returning an Option result.

returns

a function that takes an argument x to Some(this(x)) if this is defined for x, and to None otherwise.

Definition Classes
PartialFunction
See also

Function.unlift

final def map[B](f: (A) ⇒ B): List[B]

[use case]

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

B

the element type of the returned collection.

f

the function to apply to each element.

returns

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

Definition Classes
ListTraversableLikeGenTraversableLikeFilterMonadic
Full Signature

final def mapConserve(f: (B) ⇒ B): List[B]

[use case]

Builds a new list by applying a function to all elements of this list. Like xs map f, but returns xs unchanged if function f maps all elements to themselves (as determined by eq).

f

the function to apply to each element.

returns

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

Definition Classes
List
Full Signature

def max: A

[use case]

Finds the largest element.

returns

the largest element of this list.

Definition Classes
TraversableOnceGenTraversableOnce
Full Signature
Exceptions thrown

UnsupportedOperationException if this list is empty.

def maxBy[B](f: (A) ⇒ B): A

[use case]

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

B

The result type of the function f.

f

The measuring function.

returns

the first element of this list with the largest value measured by function f.

Definition Classes
TraversableOnceGenTraversableOnce
Full Signature
Exceptions thrown

UnsupportedOperationException if this list is empty.

def min: A

[use case]

Finds the smallest element.

returns

the smallest element of this list

Definition Classes
TraversableOnceGenTraversableOnce
Full Signature
Exceptions thrown

UnsupportedOperationException if this list is empty.

def minBy[B](f: (A) ⇒ B): A

[use case]

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

B

The result type of the function f.

f

The measuring function.

returns

the first element of this list with the smallest value measured by function f.

Definition Classes
TraversableOnceGenTraversableOnce
Full Signature
Exceptions thrown

UnsupportedOperationException if this list is empty.

def mkString: String

Displays all elements of this traversable or iterator in a string.

returns

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

Definition Classes
TraversableOnceGenTraversableOnce

def mkString(sep: String): String

Displays all elements of this traversable or iterator in a string using a separator string.

sep

the separator string.

returns

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

Definition Classes
TraversableOnceGenTraversableOnce
Example:

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

def mkString(start: String, sep: String, end: String): String

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

start

the starting string.

sep

the separator string.

end

the ending string.

returns

a string representation of this traversable or iterator. 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 traversable or iterator are separated by the string sep.

Definition Classes
TraversableOnceGenTraversableOnce
Example:

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

final def ne(arg0: AnyRef): Boolean

Equivalent to !(this eq that).

returns

true if the argument is not a reference to the receiver object; false otherwise.

Definition Classes
AnyRef

def newBuilder: Builder[B, List[B]]

The builder that builds instances of type Traversable[A]

Attributes
protected[this]
Definition Classes
GenericTraversableTemplateHasNewBuilder

def nonEmpty: Boolean

Tests whether the traversable or iterator is not empty.

returns

true if the traversable or iterator contains at least one element, false otherwise.

Definition Classes
TraversableOnceGenTraversableOnce

final def notify(): Unit

Wakes up a single thread that is waiting on the receiver object's monitor.

Definition Classes
AnyRef
Annotations
@native()
Note

not specified by SLS as a member of AnyRef

final def notifyAll(): Unit

Wakes up all threads that are waiting on the receiver object's monitor.

Definition Classes
AnyRef
Annotations
@native()
Note

not specified by SLS as a member of AnyRef

def orElse[A1 <: Int, B1 >: B](that: PartialFunction[A1, B1]): PartialFunction[A1, B1]

Composes this partial function with a fallback partial function which gets applied where this partial function is not defined.

A1

the argument type of the fallback function

B1

the result type of the fallback function

that

the fallback function

returns

a partial function which has as domain the union of the domains of this partial function and that. The resulting partial function takes x to this(x) where this is defined, and to that(x) where it is not.

Definition Classes
PartialFunction

def padTo(len: Int, elem: A): List[A]

[use case]

A copy of this list with an element value appended until a given target length is reached.

len

the target length

elem

the padding value

returns

a new list consisting of all elements of this list followed by the minimal number of occurrences of elem so that the resulting list has a length of at least len.

Definition Classes
SeqLikeGenSeqLike
Full Signature

def par: ParSeq[B]

Returns a parallel implementation of this collection.

For most collection types, this method creates a new parallel collection by copying all the elements. For these collection, par takes linear time. Mutable collections in this category do not produce a mutable parallel collection that has the same underlying dataset, so changes in one collection will not be reflected in the other one.

Specific collections (e.g. ParArray or mutable.ParHashMap) override this default behaviour by creating a parallel collection which shares the same underlying dataset. For these collections, par takes constant or sublinear time.

All parallel collections return a reference to themselves.

returns

a parallel implementation of this collection

Definition Classes
Parallelizable

def parCombiner: Combiner[B, ParSeq[B]]

The default par implementation uses the combiner provided by this method to create a new parallel collection.

returns

a combiner for the parallel collection of type ParRepr

Attributes
protected[this]
Definition Classes
SeqSeqLikeIterableTraversableLikeParallelizable

def partition(p: (B) ⇒ Boolean): (List[B], List[B])

Partitions this traversable collection in two traversable collections according to a predicate.

p

the predicate on which to partition.

returns

a pair of traversable collections: the first traversable collection consists of all elements that satisfy the predicate p and the second traversable collection consists of all elements that don't. The relative order of the elements in the resulting traversable collections is the same as in the original traversable collection.

Definition Classes
TraversableLikeGenTraversableLike

def patch(from: Int, that: GenSeq[A], replaced: Int): List[A]

[use case]

Produces a new list where a slice of elements in this list is replaced by another sequence.

from

the index of the first replaced element

replaced

the number of elements to drop in the original list

returns

a new list consisting of all elements of this list except that replaced elements starting from from are replaced by patch.

Definition Classes
SeqLikeGenSeqLike
Full Signature

def permutations: Iterator[List[B]]

Iterates over distinct permutations.

returns

An Iterator which traverses the distinct permutations of this sequence.

Definition Classes
SeqLike
Example:

    "abb".permutations = Iterator(abb, bab, bba)

def prefixLength(p: (B) ⇒ Boolean): Int

Returns the length of the longest prefix whose elements all satisfy some predicate.

Note: may not terminate for infinite-sized collections.

p

the predicate used to test elements.

returns

the length of the longest prefix of this general sequence such that every element of the segment satisfies the predicate p.

Definition Classes
GenSeqLike

def product: A

[use case]

Multiplies up the elements of this collection.

returns

the product of all elements in this list of numbers of type Int. Instead of Int, any other type T with an implicit Numeric[T] implementation can be used as element type of the list and as result type of product. Examples of such types are: Long, Float, Double, BigInt.

Definition Classes
TraversableOnceGenTraversableOnce
Full Signature

def reduce[A1 >: B](op: (A1, A1) ⇒ A1): A1

Reduces the elements of this traversable or iterator using the specified associative binary operator.

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

A1

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

op

A binary operator that must be associative.

returns

The result of applying reduce operator op between all the elements if the traversable or iterator is nonempty.

Definition Classes
TraversableOnceGenTraversableOnce
Exceptions thrown

UnsupportedOperationException if this traversable or iterator is empty.

def reduceLeft[B >: B](op: (B, B) ⇒ B): B

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

Note: will not terminate for infinite-sized collections.

B

the result type of the binary operator.

op

the binary operator.

returns

the result of inserting op between consecutive elements of this sequence, going left to right:

op( op( ... op(x_1, x_2) ..., x_{n-1}), x_n)

where x1, ..., xn are the elements of this sequence.

Definition Classes
LinearSeqOptimizedTraversableOnce
Exceptions thrown

UnsupportedOperationException if this sequence is empty.

def reduceLeftOption[B >: B](op: (B, B) ⇒ B): Option[B]

Optionally applies a binary operator to all elements of this traversable or iterator, 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.

B

the result type of the binary operator.

op

the binary operator.

returns

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

Definition Classes
TraversableOnceGenTraversableOnce

def reduceOption[A1 >: B](op: (A1, A1) ⇒ A1): Option[A1]

Reduces the elements of this traversable or iterator, if any, using the specified associative binary operator.

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

A1

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

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.

Definition Classes
TraversableOnceGenTraversableOnce

def reduceRight[B >: B](op: (B, B) ⇒ B): B

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

Note: will not terminate for infinite-sized collections.

B

the result type of the binary operator.

op

the binary operator.

returns

the result of inserting op between consecutive elements of this sequence, going right to left:

op(x_1, op(x_2, ..., op(x_{n-1}, x_n)...))

where x1, ..., xn are the elements of this sequence.

Definition Classes
LinearSeqOptimizedIterableLikeTraversableOnceGenTraversableOnce
Exceptions thrown

UnsupportedOperationException if this sequence is empty.

def reduceRightOption[B >: B](op: (B, B) ⇒ B): Option[B]

Optionally applies a binary operator to all elements of this traversable or iterator, 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.

B

the result type of the binary operator.

op

the binary operator.

returns

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

Definition Classes
TraversableOnceGenTraversableOnce

def repr: List[B]

The collection of type traversable collection underlying this TraversableLike object. By default this is implemented as the TraversableLike object itself, but this can be overridden.

Definition Classes
TraversableLikeGenTraversableLike

def reverse: List[B]

Returns new list with elements in reversed order.

returns

A new list with all elements of this list in reversed order.

Definition Classes
ListSeqLikeGenSeqLike

def reverseIterator: Iterator[B]

An iterator yielding elements in reversed order.

Note: will not terminate for infinite-sized collections.

Note: xs.reverseIterator is the same as xs.reverse.iterator but might be more efficient.

returns

an iterator yielding the elements of this sequence in reversed order

Definition Classes
SeqLike

def reverseMap[B](f: (A) ⇒ B): List[B]

[use case]

Builds a new collection by applying a function to all elements of this list and collecting the results in reversed order.

Note: xs.reverseMap(f) is the same as xs.reverse.map(f) but might be more efficient.

B

the element type of the returned collection.

f

the function to apply to each element.

returns

a new list resulting from applying the given function f to each element of this list and collecting the results in reversed order.

Definition Classes
SeqLikeGenSeqLike
Full Signature

def reverse_:::(prefix: List[B]): List[B]

[use case]

Adds the elements of a given list in reverse order in front of this list. xs reverse_::: ys is equivalent to xs.reverse ::: ys but is more efficient.

prefix

the prefix to reverse and then prepend

returns

the concatenation of the reversed prefix and the current list.

Definition Classes
List
Full Signature

def reversed: scala.List[B]

Attributes
protected[this]
Definition Classes
TraversableOnce

def runWith[U](action: (B) ⇒ U): (Int) ⇒ Boolean

Composes this partial function with an action function which gets applied to results of this partial function. The action function is invoked only for its side effects; its result is ignored.

Note that expression pf.runWith(action)(x) is equivalent to

if(pf isDefinedAt x) { action(pf(x)); true } else false

except that runWith is implemented via applyOrElse and thus potentially more efficient. Using runWith avoids double evaluation of pattern matchers and guards for partial function literals.

action

the action function

returns

a function which maps arguments x to isDefinedAt(x). The resulting function runs action(this(x)) where this is defined.

Definition Classes
PartialFunction
Since

2.10

See also

applyOrElse.

def sameElements(that: GenIterable[A]): Boolean

[use case]

Checks if the other iterable collection contains the same elements in the same order as this list.

that

the collection to compare with.

returns

true, if both collections contain the same elements in the same order, false otherwise.

Definition Classes
LinearSeqOptimizedIterableLikeGenIterableLike
Full Signature

def scan[B >: B, That](z: B)(op: (B, B) ⇒ B)(implicit cbf: CanBuildFrom[List[B], B, That]): That

Computes a prefix scan of the elements of the collection.

Note: The neutral element z may be applied more than once.

B

element type of the resulting collection

That

type of the resulting collection

z

neutral element for the operator op

op

the associative operator for the scan

cbf

combiner factory which provides a combiner

returns

a new traversable collection containing the prefix scan of the elements in this traversable collection

Definition Classes
TraversableLikeGenTraversableLike

def scanLeft[B, That](z: B)(op: (B, B) ⇒ B)(implicit bf: CanBuildFrom[List[B], B, That]): That

Produces a collection containing cumulative results of applying the operator 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.

B

the type of the elements in the resulting collection

That

the actual type of the resulting collection

z

the initial value

op

the binary operator applied to the intermediate result and the element

bf

an implicit value of class CanBuildFrom which determines the result class That from the current representation type Repr and the new element type B.

returns

collection with intermediate results

Definition Classes
TraversableLikeGenTraversableLike

def scanRight[B, That](z: B)(op: (B, B) ⇒ B)(implicit bf: CanBuildFrom[List[B], B, That]): That

Produces a collection containing cumulative results of applying the operator going right to left. The head of the collection is the last cumulative result.

Note: will not terminate for infinite-sized collections.

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

Example:

List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)
B

the type of the elements in the resulting collection

That

the actual type of the resulting collection

z

the initial value

op

the binary operator applied to the intermediate result and the element

bf

an implicit value of class CanBuildFrom which determines the result class That from the current representation type Repr and the new element type B.

returns

collection with intermediate results

Definition Classes
TraversableLikeGenTraversableLike
Annotations
@migration
Migration

(Changed in version 2.9.0) The behavior of scanRight has changed. The previous behavior can be reproduced with scanRight.reverse.

def segmentLength(p: (B) ⇒ Boolean, from: Int): Int

Computes length of longest segment whose elements all satisfy some predicate.

Note: may not terminate for infinite-sized collections.

p

the predicate used to test elements.

from

the index where the search starts.

returns

the length of the longest segment of this sequence starting from index from such that every element of the segment satisfies the predicate p.

Definition Classes
LinearSeqOptimizedSeqLikeGenSeqLike

def seq: LinearSeq[B]

A version of this collection with all of the operations implemented sequentially (i.e., in a single-threaded manner).

This method returns a reference to this collection. In parallel collections, it is redefined to return a sequential implementation of this collection. In both cases, it has O(1) complexity.

returns

a sequential view of the collection.

Definition Classes
LinearSeqLinearSeqLinearSeqLikeSeqSeqGenSeqGenSeqLikeIterableIterableGenIterableTraversableTraversableGenTraversableParallelizableTraversableOnceGenTraversableOnce

def size: Int

The size of this sequence, equivalent to length.

Note: will not terminate for infinite-sized collections.

returns

the number of elements in this sequence.

Definition Classes
SeqLikeGenTraversableLikeTraversableOnceGenTraversableOnce

def sizeHintIfCheap: Int

The size of this collection or iterator, if it can be cheaply computed

returns

the number of elements in this collection or iterator, or -1 if the size cannot be determined cheaply

Attributes
protected[collection]
Definition Classes
GenTraversableOnce

def slice(from: Int, until: Int): List[B]

returns

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

Definition Classes
ListLinearSeqOptimizedIterableLikeTraversableLikeGenTraversableLike
Example:
    // Given a list
    val letters = List('a','b','c','d','e')
    
    // `slice` returns all elements beginning at index `from` and afterwards,
    // up until index `until` (excluding index `until`.)
    letters.slice(1,3) // Returns List('b','c')

def sliding(size: Int, step: Int): Iterator[List[B]]

Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)

size

the number of elements per group

step

the distance between the first elements of successive groups

returns

An iterator producing iterable collections of size size, except the last element (which may be the only element) will be truncated if there are fewer than size elements remaining to be grouped.

Definition Classes
IterableLike
See also

scala.collection.Iterator, method sliding

def sliding(size: Int): Iterator[List[B]]

Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.) The "sliding window" step is set to one.

size

the number of elements per group

returns

An iterator producing iterable collections of size size, except the last element (which may be the only element) will be truncated if there are fewer than size elements remaining to be grouped.

Definition Classes
IterableLike
See also

scala.collection.Iterator, method sliding

def sortBy[B](f: (B) ⇒ B)(implicit ord: math.Ordering[B]): List[B]

Sorts this Seq according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.

B

the target type of the transformation f, and the type where the ordering ord is defined.

f

the transformation function mapping elements to some other domain B.

ord

the ordering assumed on domain B.

returns

a sequence consisting of the elements of this sequence sorted according to the ordering where x < y if ord.lt(f(x), f(y)).

Definition Classes
SeqLike
Example:
    val words = "The quick brown fox jumped over the lazy dog".split(' ')
    // this works because scala.Ordering will implicitly provide an Ordering[Tuple2[Int, Char]]
    words.sortBy(x => (x.length, x.head))
    res0: Array[String] = Array(The, dog, fox, the, lazy, over, brown, quick, jumped)
See also

scala.math.Ordering Note: will not terminate for infinite-sized collections.

def sortWith(lt: (B, B) ⇒ Boolean): List[B]

Sorts this sequence according to a comparison function.

Note: will not terminate for infinite-sized collections.

The sort is stable. That is, elements that are equal (as determined by lt) appear in the same order in the sorted sequence as in the original.

lt

the comparison function which tests whether its first argument precedes its second argument in the desired ordering.

returns

a sequence consisting of the elements of this sequence sorted according to the comparison function lt.

Definition Classes
SeqLike
Example:
    List("Steve", "Tom", "John", "Bob").sortWith(_.compareTo(_) < 0) =
    List("Bob", "John", "Steve", "Tom")

def sorted[B >: B](implicit ord: math.Ordering[B]): List[B]

Sorts this sequence according to an Ordering.

The sort is stable. That is, elements that are equal (as determined by lt) appear in the same order in the sorted sequence as in the original.

ord

the ordering to be used to compare elements.

returns

a sequence consisting of the elements of this sequence sorted according to the ordering ord.

Definition Classes
SeqLike
See also

scala.math.Ordering

final def span(p: (B) ⇒ Boolean): (List[B], List[B])

Splits this list 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.

returns

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

Definition Classes
ListLinearSeqOptimizedTraversableLikeGenTraversableLike
Annotations
@inline()

def splitAt(n: Int): (List[B], List[B])

Splits this list into two at a given position. Note: c splitAt n is equivalent to (but possibly more efficient than) (c take n, c drop n).

n

the position at which to split.

returns

a pair of lists consisting of the first n elements of this list, and the other elements.

Definition Classes
ListTraversableLikeGenTraversableLike

def startsWith[B](that: GenSeq[B], offset: Int): Boolean

Tests whether this sequence contains the given sequence at a given index.

Note: If the both the receiver object this and the argument that are infinite sequences this method may not terminate.

that

the sequence to test

offset

the index where the sequence is searched.

returns

true if the sequence that is contained in this sequence at index offset, otherwise false.

Definition Classes
SeqLikeGenSeqLike

def startsWith[B](that: GenSeq[B]): Boolean

Tests whether this general sequence starts with the given sequence.

that

the sequence to test

returns

true if this collection has that as a prefix, false otherwise.

Definition Classes
GenSeqLike

def stringPrefix: String

Defines the prefix of this object's toString representation.

returns

a string representation which starts the result of toString applied to this list. By default the string prefix is the simple name of the collection class list.

Definition Classes
ListTraversableLikeGenTraversableLike

def sum: A

[use case]

Sums up the elements of this collection.

returns

the sum of all elements in this list of numbers of type Int. Instead of Int, any other type T with an implicit Numeric[T] implementation can be used as element type of the list and as result type of sum. Examples of such types are: Long, Float, Double, BigInt.

Definition Classes
TraversableOnceGenTraversableOnce
Full Signature

final def synchronized[T0](arg0: ⇒ T0): T0

Definition Classes
AnyRef

def tail: List[B]

Selects all elements except the first.

returns

a list consisting of all elements of this list except the first one.

Definition Classes
::ListLinearSeqOptimizedTraversableLikeGenTraversableLike
Exceptions thrown

UnsupportedOperationException if the list is empty.

def tails: Iterator[List[B]]

Iterates over the tails of this sequence. The first value will be this sequence and the final one will be an empty sequence, with the intervening values the results of successive applications of tail.

returns

an iterator over all the tails of this sequence

Definition Classes
LinearSeqOptimizedTraversableLike
Example:

    List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)

def take(n: Int): List[B]

Selects first n elements.

n

the number of elements to take from this list.

returns

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

Definition Classes
ListLinearSeqOptimizedIterableLikeTraversableLikeGenTraversableLike

def takeRight(n: Int): List[B]

Selects last n elements.

n

the number of elements to take

returns

a list consisting only of the last n elements of this list, or else the whole list, if it has less than n elements.

Definition Classes
ListIterableLike

final def takeWhile(p: (B) ⇒ Boolean): List[B]

Takes longest prefix of elements that satisfy a predicate.

returns

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

Definition Classes
ListLinearSeqOptimizedIterableLikeTraversableLikeGenTraversableLike
Annotations
@inline()

def thisCollection: collection.LinearSeq[B]

The underlying collection seen as an instance of Seq. By default this is implemented as the current collection object itself, but this can be overridden.

Attributes
protected[this]
Definition Classes
LinearSeqLikeSeqLikeIterableLikeTraversableLike

def to[Col[_]]: Col[A]

[use case]

Converts this list into another by copying all elements.

Col

The collection type to build.

returns

a new collection containing all elements of this list.

Definition Classes
TraversableLikeTraversableOnceGenTraversableOnce
Full Signature

def toArray: Array[A]

[use case]

Converts this list to an array.

returns

an array containing all elements of this list. An ClassTag must be available for the element type of this list.

Definition Classes
TraversableOnceGenTraversableOnce
Full Signature

def toBuffer[B >: B]: Buffer[B]

Uses the contents of this traversable or iterator to create a new mutable buffer.

Note: will not terminate for infinite-sized collections.

returns

a buffer containing all elements of this traversable or iterator.

Definition Classes
TraversableOnceGenTraversableOnce

def toCollection(repr: List[B]): collection.LinearSeq[B]

A conversion from collections of type Repr to Seq objects. By default this is implemented as just a cast, but this can be overridden.

Attributes
protected[this]
Definition Classes
LinearSeqLikeSeqLikeIterableLikeTraversableLike

def toIndexedSeq: IndexedSeq[B]

Converts this traversable or iterator to an indexed sequence.

Note: will not terminate for infinite-sized collections.

returns

an indexed sequence containing all elements of this traversable or iterator.

Definition Classes
TraversableOnceGenTraversableOnce

def toIterable: collection.Iterable[B]

Returns this iterable collection as an iterable collection.

A new collection will not be built; lazy collections will stay lazy.

Note: will not terminate for infinite-sized collections.

returns

an Iterable containing all elements of this iterable collection.

Definition Classes
IterableLikeTraversableOnceGenTraversableOnce

def toIterator: Iterator[B]

Returns an Iterator over the elements in this iterable collection. Produces the same result as iterator.

Note: will not terminate for infinite-sized collections.

returns

an Iterator containing all elements of this iterable collection.

Definition Classes
IterableLikeTraversableLikeGenTraversableOnce
Annotations
@deprecatedOverriding( message = ... , since = "2.11.0" )

def toList: List[B]

Converts this list to a list.

returns

a list containing all elements of this list.

Definition Classes
ListTraversableOnceGenTraversableOnce

def toMap[T, U]: collection.Map[T, U]

[use case]

Converts this list to a map. This method is unavailable unless the elements are members of Tuple2, each ((T, U)) becoming a key-value pair in the map. Duplicate keys will be overwritten by later keys: if this is an unordered collection, which key is in the resulting map is undefined.

returns

a map of type immutable.Map[T, U] containing all key/value pairs of type (T, U) of this list.

Definition Classes
TraversableOnceGenTraversableOnce
Full Signature

def toParArray: ParArray[T]

Implicit
This member is added by an implicit conversion from ::[B] to CollectionsHaveToParArray[::[B], T] performed by method CollectionsHaveToParArray in scala.collection.parallel. This conversion will take place only if an implicit value of type (::[B]) ⇒ GenTraversableOnce[T] is in scope.
Definition Classes
CollectionsHaveToParArray

def toSeq: Seq[B]

Converts this immutable sequence to a sequence.

Note: will not terminate for infinite-sized collections.

A new collection will not be built; in particular, lazy sequences will stay lazy.

returns

a sequence containing all elements of this immutable sequence.

Definition Classes
SeqSeqLikeGenSeqLikeTraversableOnceGenTraversableOnce

def toSet[B >: B]: Set[B]

Converts this traversable or iterator to a set.

Note: will not terminate for infinite-sized collections.

returns

a set containing all elements of this traversable or iterator.

Definition Classes
TraversableOnceGenTraversableOnce

def toStream: Stream[B]

Converts this list to a stream.

returns

a stream containing all elements of this list.

Definition Classes
ListIterableLikeTraversableLikeGenTraversableOnce

def toString(): String

Converts this sequence to a string.

returns

a string representation of this collection. By default this string consists of the stringPrefix of this sequence, followed by all elements separated by commas and enclosed in parentheses.

Definition Classes
SeqLikeTraversableLikeAny

def toTraversable: collection.Traversable[B]

Converts this traversable collection to an unspecified Traversable. Will return the same collection if this instance is already Traversable.

Note: will not terminate for infinite-sized collections.

returns

a Traversable containing all elements of this traversable collection.

Definition Classes
TraversableLikeTraversableOnceGenTraversableOnce
Annotations
@deprecatedOverriding( message = ... , since = "2.11.0" )

def toVector: scala.Vector[B]

Converts this traversable or iterator to a Vector.

Note: will not terminate for infinite-sized collections.

returns

a vector containing all elements of this traversable or iterator.

Definition Classes
TraversableOnceGenTraversableOnce

def transpose[B](implicit asTraversable: (B) ⇒ GenTraversableOnce[B]): List[List[B]]

Transposes this collection of traversable collections into a collection of collections.

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

val xs = List(
           Set(1, 2, 3),
           Set(4, 5, 6)).transpose
// xs == List(
//         List(1, 4),
//         List(2, 5),
//         List(3, 6))

val ys = Vector(
           List(1, 2, 3),
           List(4, 5, 6)).transpose
// ys == Vector(
//         Vector(1, 4),
//         Vector(2, 5),
//         Vector(3, 6))
B

the type of the elements of each traversable collection.

asTraversable

an implicit conversion which asserts that the element type of this collection is a Traversable.

returns

a two-dimensional collection of collections which has as nth row the nth column of this collection.

Definition Classes
GenericTraversableTemplate
Annotations
@migration
Migration

(Changed in version 2.9.0) transpose throws an IllegalArgumentException if collections are not uniformly sized.

Exceptions thrown

IllegalArgumentException if all collections in this collection are not of the same size.

def union(that: collection.Seq[B]): List[B]

[use case]

Produces a new sequence which contains all elements of this list and also all elements of a given sequence. xs union ys is equivalent to xs ++ ys.

Another way to express this is that xs union ys computes the order-preserving multi-set union of xs and ys. union is hence a counter-part of diff and intersect which also work on multi-sets.

that

the sequence to add.

returns

a new list which contains all elements of this list followed by all elements of that.

Definition Classes
SeqLikeGenSeqLike
Full Signature

def unzip[A1, A2](implicit asPair: (B) ⇒ (A1, A2)): (List[A1], List[A2])

Converts this collection of pairs into two collections of the first and second half of each pair.

val xs = Traversable(
           (1, "one"),
           (2, "two"),
           (3, "three")).unzip
// xs == (Traversable(1, 2, 3),
//        Traversable(one, two, three))
A1

the type of the first half of the element pairs

A2

the type of the second half of the element pairs

asPair

an implicit conversion which asserts that the element type of this collection is a pair.

returns

a pair of collections, containing the first, respectively second half of each element pair of this collection.

Definition Classes
GenericTraversableTemplate

def unzip3[A1, A2, A3](implicit asTriple: (B) ⇒ (A1, A2, A3)): (List[A1], List[A2], List[A3])

Converts this collection of triples into three collections of the first, second, and third element of each triple.

val xs = Traversable(
           (1, "one", '1'),
           (2, "two", '2'),
           (3, "three", '3')).unzip3
// xs == (Traversable(1, 2, 3),
//        Traversable(one, two, three),
//        Traversable(1, 2, 3))
A1

the type of the first member of the element triples

A2

the type of the second member of the element triples

A3

the type of the third member of the element triples

asTriple

an implicit conversion which asserts that the element type of this collection is a triple.

returns

a triple of collections, containing the first, second, respectively third member of each element triple of this collection.

Definition Classes
GenericTraversableTemplate

def updated(index: Int, elem: A): List[A]

[use case]

A copy of this list with one single replaced element.

index

the position of the replacement

elem

the replacing element

returns

a copy of this list with the element at position index replaced by elem.

Definition Classes
SeqLikeGenSeqLike
Full Signature

def view(from: Int, until: Int): SeqView[B, List[B]]

Creates a non-strict view of a slice of this sequence.

Note: the difference between view and slice is that view produces a view of the current sequence, whereas slice produces a new sequence.

Note: view(from, to) is equivalent to view.slice(from, to)

from

the index of the first element of the view

until

the index of the element following the view

returns

a non-strict view of a slice of this sequence, starting at index from and extending up to (but not including) index until.

Definition Classes
SeqLikeIterableLikeTraversableLike

def view: SeqView[B, List[B]]

Creates a non-strict view of this sequence.

returns

a non-strict view of this sequence.

Definition Classes
SeqLikeIterableLikeTraversableLike

final def wait(): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )

final def wait(arg0: Long, arg1: Int): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )

final def wait(arg0: Long): Unit

Definition Classes
AnyRef
Annotations
@throws( ... ) @native()

def withFilter(p: (B) ⇒ Boolean): FilterMonadic[B, List[B]]

Creates a non-strict filter of this traversable collection.

Note: the difference between c filter p and c withFilter p is that the former creates a new collection, whereas the latter only restricts the domain of subsequent map, flatMap, foreach, and withFilter operations.

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

p

the predicate used to test elements.

returns

an object of class WithFilter, which supports map, flatMap, foreach, and withFilter operations. All these operations apply to those elements of this traversable collection which satisfy the predicate p.

Definition Classes
TraversableLikeFilterMonadic

final def writeReplace(): AnyRef

Attributes
protected
Definition Classes
List

def zip[B](that: GenIterable[B]): List[(A, B)]

[use case]

Returns a list formed from this list and another iterable collection by combining corresponding elements in pairs. If one of the two collections is longer than the other, its remaining elements are ignored.

B

the type of the second half of the returned pairs

that

The iterable providing the second half of each result pair

returns

a new list containing pairs consisting of corresponding elements of this list and that. The length of the returned collection is the minimum of the lengths of this list and that.

Definition Classes
IterableLikeGenIterableLike
Full Signature

def zipAll[B](that: collection.Iterable[B], thisElem: A, thatElem: B): List[(A, B)]

[use case]

Returns a list formed from this list and another iterable collection by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.

B

the type of the second half of the returned pairs

that

The iterable providing the second half of each result pair

thisElem

the element to be used to fill up the result if this list is shorter than that.

thatElem

the element to be used to fill up the result if that is shorter than this list.

returns

a new list containing pairs consisting of corresponding elements of this list and that. The length of the returned collection is the maximum of the lengths of this list and that. If this list is shorter than that, thisElem values are used to pad the result. If that is shorter than this list, thatElem values are used to pad the result.

Definition Classes
IterableLikeGenIterableLike
Full Signature

def zipWithIndex: List[(A, Int)]

[use case]

Zips this list with its indices.

returns

A new list containing pairs consisting of all elements of this list paired with their index. Indices start at 0.

Definition Classes
IterableLikeGenIterableLike
Full Signature
Example:

    List("a", "b", "c").zipWithIndex = List(("a", 0), ("b", 1), ("c", 2))

def [B](y: B): (::[B], B)

Implicit
This member is added by an implicit conversion from ::[B] to ArrowAssoc[::[B]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc

Shadowed Implicit Value Members

def filter(p: (B) ⇒ Boolean): TraversableOnce[B]

Implicit
This member is added by an implicit conversion from ::[B] to MonadOps[B] performed by method MonadOps in scala.collection.TraversableOnce.
Shadowing
This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:
(::: MonadOps[B]).filter(p)
Definition Classes
MonadOps

def flatMap[B](f: (B) ⇒ GenTraversableOnce[B]): TraversableOnce[B]

Implicit
This member is added by an implicit conversion from ::[B] to MonadOps[B] performed by method MonadOps in scala.collection.TraversableOnce.
Shadowing
This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:
(::: MonadOps[B]).flatMap(f)
Definition Classes
MonadOps

def map[B](f: (B) ⇒ B): TraversableOnce[B]

Implicit
This member is added by an implicit conversion from ::[B] to MonadOps[B] performed by method MonadOps in scala.collection.TraversableOnce.
Shadowing
This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:
(::: MonadOps[B]).map(f)
Definition Classes
MonadOps

def withFilter(p: (B) ⇒ Boolean): Iterator[B]

Implicit
This member is added by an implicit conversion from ::[B] to MonadOps[B] performed by method MonadOps in scala.collection.TraversableOnce.
Shadowing
This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:
(::: MonadOps[B]).withFilter(p)
Definition Classes
MonadOps

© 2002-2019 EPFL, with contributions from Lightbend.
Licensed under the Apache License, Version 2.0.
https://www.scala-lang.org/api/2.12.9/scala/collection/immutable/$colon$colon.html