List

Companion object List

sealed abstract class List[+A] extends AbstractSeq[A] with LinearSeq[A] with LinearSeqOps[A, List, List[A]] with StrictOptimizedLinearSeqOps[A, List, List[A]] with StrictOptimizedSeqOps[A, List, List[A]] with IterableFactoryDefaults[A, List] with DefaultSerializable

A class for immutable linked lists representing ordered collections of elements of type A.

This class comes with two implementing case classes scala.Nil and scala.:: that implement the abstract members isEmpty, head and tail.

This class is optimal for last-in-first-out (LIFO), stack-like access patterns. If you need another access pattern, for example, random access or FIFO, consider using a collection more suited to this than List.

Performance

Time: List has O(1) prepend and head/tail access. Most other operations are O(n) on the number of elements in the list. This includes the index-based lookup of elements, length, append and reverse.

Space: List implements structural sharing of the tail list. This means that many operations are either zero- or constant-memory cost.

val mainList = List(3, 2, 1)
val with4 =    4 :: mainList  // re-uses mainList, costs one :: instance
val with42 =   42 :: mainList // also re-uses mainList, cost one :: instance
val shorter =  mainList.tail  // costs nothing as it uses the same 2::1::Nil instances as mainList

Annotations: @SerialVersionUID()
Source: List.scala
Note: The functional list is characterized by persistence and structural sharing, thus offering considerable performance and space consumption benefits in some scenarios if used correctly. However, note that objects having multiple references into the same functional list (that is, objects that rely on structural sharing), will be serialized and deserialized with multiple lists, one for each reference to it. I.e. structural sharing is lost after serialization/deserialization.
See also: "Scala's Collection Library overview" section on Lists for more information.

Linear Supertypes

DefaultSerializable, java.io.Serializable, StrictOptimizedSeqOps[A, List, List[A]], StrictOptimizedLinearSeqOps[A, List, List[A]], collection.StrictOptimizedSeqOps[A, List, List[A]], StrictOptimizedIterableOps[A, List, List[A]], LinearSeq[A], LinearSeqOps[A, [X]List[X], List[A]], collection.LinearSeq[A], collection.LinearSeqOps[A, [X]List[X], List[A]], AbstractSeq[A], Seq[A], SeqOps[A, [_]List[_], List[A]], Iterable[A], collection.AbstractSeq[A], collection.Seq[A], Equals, collection.SeqOps[A, [_]List[_], List[A]], PartialFunction[Int, A], (Int) => A, AbstractIterable[A], collection.Iterable[A], IterableFactoryDefaults[A, [x]List[x]], IterableOps[A, [_]List[_], List[A]], IterableOnceOps[A, [_]List[_], List[A]], IterableOnce[A], AnyRef, Any

Known Subclasses

::, Nil

Type Hierarchy

Ordering

Alphabetic
By Inheritance

Inherited

List
DefaultSerializable
Serializable
StrictOptimizedSeqOps
StrictOptimizedLinearSeqOps
StrictOptimizedSeqOps
StrictOptimizedIterableOps
LinearSeq
LinearSeqOps
LinearSeq
LinearSeqOps
AbstractSeq
Seq
SeqOps
Iterable
AbstractSeq
Seq
Equals
SeqOps
PartialFunction
Function1
AbstractIterable
Iterable
IterableFactoryDefaults
IterableOps
IterableOnceOps
IterableOnce
AnyRef
Any

Implicitly

by UnliftOps
by iterableOnceExtensionMethods
by any2stringadd
by StringFormat
by Ensuring
by ArrowAssoc

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Visibility

Public
Protected

Value Members

final def !=(arg0: Any): Boolean
Test two objects for inequality.
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.
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 List[A] toany2stringadd[List[A]] performed by method any2stringadd in scala.Predef.
Definition Classes
any2stringadd
final def ++[B >: A](suffix: IterableOnce[B]): List[B]
Alias for concat
Alias for concat
Definition Classes
IterableOps
Annotations
@inline()
final def ++:[B >: A](prefix: IterableOnce[B]): List[B]
Alias for prependedAll
Alias for prependedAll
Definition Classes
SeqOps → IterableOps
Annotations
@inline()
final def +:[B >: A](elem: B): List[B]
Alias for prepended.
Alias for prepended.
Note that :-ending operators are right associative (see example). A mnemonic for +: vs. :+ is: the COLon goes on the COLlection side.
Definition Classes
SeqOps
Annotations
@inline()
def ->[B](y: B): (List[A], B)
Implicit
This member is added by an implicit conversion from List[A] toArrowAssoc[List[A]] performed by method ArrowAssoc in scala.Predef.This conversion will take place only if A is a subclass of Option[Nothing] (A <: Option[Nothing]).
Definition Classes
ArrowAssoc
Annotations
@inline()
final def :+[B >: A](elem: B): List[B]
Alias for appended
Alias for appended
Note that :-ending operators are right associative (see example). A mnemonic for +: vs. :+ is: the COLon goes on the COLlection side.
Definition Classes
SeqOps
Annotations
@inline()
final def :++[B >: A](suffix: IterableOnce[B]): List[B]
Alias for appendedAll
Alias for appendedAll
Definition Classes
SeqOps
Annotations
@inline()
def ::[B >: A](elem: B): List[B]
Adds an element at the beginning of this list.
Adds an element at the beginning of this list.
elem
the element to prepend.
returns
a list which contains x as first element and which continues with this list. Example:
```
1 :: List(2, 3) = List(2, 3).::(1) = List(1, 2, 3)
```
def :::[B >: A](prefix: List[B]): List[B]
Adds the elements of a given list in front of this list.
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.
final def ==(arg0: Any): Boolean
The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).
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
final def addString(b: mutable.StringBuilder): b.type
Appends all elements of this list to a string builder.
Appends all elements of this list to a string builder. The written text consists of the string representations (w.r.t. the method toString) of all elements of this list 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
IterableOnceOps
Annotations
@inline()
final def addString(b: mutable.StringBuilder, sep: String): b.type
Appends all elements of this list to a string builder using a separator string.
Appends all elements of this list 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 list, 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
IterableOnceOps
Annotations
@inline()
def addString(b: mutable.StringBuilder, start: String, sep: String, end: String): b.type
Appends all elements of this list to a string builder using start, end, and separator strings.
Appends all elements of this list 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 list 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
IterableOnceOps
def andThen[C](k: PartialFunction[A, C]): PartialFunction[Int, C]
Composes this partial function with another partial function that gets applied to results of this partial function.
Composes this partial function with another partial function that gets applied to results of this partial function.
Note that calling isDefinedAt on the resulting partial function may apply the first partial function and execute its side effect. For efficiency, it is recommended to call applyOrElse instead of isDefinedAt or apply.
C
the result type of the transformation function.
k
the transformation function
returns
a partial function with the domain of this partial function narrowed by other partial function, which maps arguments x to k(this(x)).
Definition Classes
PartialFunction
def andThen[C](k: (A) => C): PartialFunction[Int, C]
Composes this partial function with a transformation function that gets applied to results of this partial function.
Composes this partial function with a transformation function that gets applied to results of this partial function.
If the runtime type of the function is a PartialFunction then the other andThen method is used (note its cautions).
C
the result type of the transformation function.
k
the transformation function
returns
a partial function with the domain of this partial function, possibly narrowed by the specified function, which maps arguments x to k(this(x)).
Definition Classes
PartialFunction → Function1
def appended[B >: A](elem: B): List[B]
A copy of this list with an element appended.
A copy of this list with an element appended.
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)
```
B
the element type of the returned list.
elem
the appended element
returns
a new list consisting of all elements of this list followed by value.
Definition Classes
StrictOptimizedSeqOps → SeqOps
def appendedAll[B >: A](suffix: IterableOnce[B]): List[B]
Returns a new list containing the elements from the left hand operand followed by the elements from the right hand operand.
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.
suffix
the iterable to append.
returns
a new collection of type CC[B] which contains all elements of this list followed by all elements of suffix.
Definition Classes
List → StrictOptimizedSeqOps → SeqOps
def apply(n: Int): A
Get the element at the specified index.
Get the element at the specified index. This operation is provided for convenience in Seq. It should not be assumed to be efficient unless you have an IndexedSeq.
Definition Classes
LinearSeqOps → SeqOps
Annotations
@throws(cause = scala.this.throws.<init>$default$1[IndexOutOfBoundsException])
def applyOrElse[A1 <: Int, B1 >: A](x: A1, default: (A1) => B1): B1
Applies this partial function to the given argument when it is contained in the function domain.
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
final def asInstanceOf[T0]: T0
Cast the receiver object to be of type 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
A method that should be called from every well-designed equals method that is open to be overridden in a subclass.
A method that should be called from every well-designed equals method that is open to be overridden in a subclass. See Programming in Scala, Chapter 28 for discussion and design.
that
the value being probed for possible equality
returns
true if this instance can possibly equal that, otherwise false
Definition Classes
Seq → Equals
def className: String
Defines the prefix of this object's toString representation.
Defines the prefix of this object's toString representation.
It is recommended to return the name of the concrete collection type, but not implementation subclasses. For example, for ListMap this method should return "ListMap", not "Map" (the supertype) or "Node" (an implementation subclass).
The default implementation returns "Iterable". It is overridden for the basic collection kinds "Seq", "IndexedSeq", "LinearSeq", "Buffer", "Set", "Map", "SortedSet", "SortedMap" and "View".
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.
Attributes
protected[this]
Definition Classes
List → Iterable
def clone(): AnyRef
Create a copy of the receiver object.
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(classOf[java.lang.CloneNotSupportedException]) @native()
Note
not specified by SLS as a member of AnyRef
final def coll: List.this.type
returns
This collection as a C.
Attributes
protected
Definition Classes
Iterable → IterableOps
final def collect[B](pf: PartialFunction[A, B]): List[B]
Builds a new list by applying a partial function to all elements of this list on which the function is defined.
Builds a new list by applying a partial function to all elements of this list on which the function is defined.
B
the element type of the returned list.
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
List → StrictOptimizedIterableOps → IterableOps → IterableOnceOps
def collectFirst[B](pf: PartialFunction[A, B]): Option[B]
Finds the first element of the list for which the given partial function is defined, and applies the partial function to it.
Finds the first element of the list for which the given partial function is defined, and applies the partial function to it.
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
IterableOnceOps
Example:
1. Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)
def combinations(n: Int): Iterator[List[A]]
Iterates over combinations of elements.
Iterates over combinations of elements.
A combination of length n is a sequence of n elements selected in order of their first index in this sequence.
For example, "xyx" has two combinations of length 2. The x is selected first: "xx", "xy". The sequence "yx" is not returned as a combination because it is subsumed by "xy".
If there is more than one way to generate the same combination, only one will be returned.
For example, the result "xy" arbitrarily selected one of the x elements.
As a further illustration, "xyxx" has three different ways to generate "xy" because there are three elements x to choose from. Moreover, there are three unordered pairs "xx" but only one is returned.
It is not specified which of these equal combinations is returned. It is an implementation detail that should not be relied on. For example, the combination "xx" does not necessarily contain the first x in this sequence. This behavior is observable if the elements compare equal but are not identical.
As a consequence, "xyx".combinations(3).next() is "xxy": the combination does not reflect the order of the original sequence, but the order in which elements were selected, by "first index"; the order of each x element is also arbitrary.
Note: Even when applied to a view or a lazy collection it will always force the elements.
returns
An Iterator which traverses the n-element combinations of this list.
Definition Classes
SeqOps
Example:
1. Seq('a', 'b', 'b', 'b', 'c').combinations(2).foreach(println) // List(a, b) // List(a, c) // List(b, b) // List(b, c) Seq('b', 'a', 'b').combinations(2).foreach(println) // List(b, b) // List(b, a)
def compose[R](k: PartialFunction[R, Int]): PartialFunction[R, A]
Composes another partial function k with this partial function so that this partial function gets applied to results of k.
Composes another partial function k with this partial function so that this partial function gets applied to results of k.
Note that calling isDefinedAt on the resulting partial function may apply the first partial function and execute its side effect. For efficiency, it is recommended to call applyOrElse instead of isDefinedAt or apply.
R
the parameter type of the transformation function.
k
the transformation function
returns
a partial function with the domain of other partial function narrowed by this partial function, which maps arguments x to this(k(x)).
Definition Classes
PartialFunction
def compose[A](g: (A) => Int): (A) => A
Composes two instances of Function1 in a new Function1, with this function applied last.
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()
final def concat[B >: A](suffix: IterableOnce[B]): List[B]
Returns a new list containing the elements from the left hand operand followed by the elements from the right hand operand.
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.
suffix
the traversable to append.
returns
a new list which contains all elements of this list followed by all elements of suffix.
Definition Classes
SeqOps → IterableOps
Annotations
@inline()
final def contains[A1 >: A](elem: A1): Boolean
Tests whether this list contains a given value as an element.
Tests whether this list contains a given value as an element.
elem
the element to test.
returns
true if this list has an element that is equal (as determined by ==) to elem, false otherwise.
Definition Classes
List → LinearSeqOps → SeqOps
def containsSlice[B >: A](that: collection.Seq[B]): Boolean
Tests whether this list contains a given sequence as a slice.
Tests whether this list contains a given sequence as a slice.
that
the sequence to test
returns
true if this list contains a slice with the same elements as that, otherwise false.
Definition Classes
SeqOps
def copyToArray[B >: A](xs: Array[B], start: Int, len: Int): Int
Copy elements to an array, returning the number of elements written.
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 list.
Copying will stop once either all the elements of this list have been copied, or the end of the array is reached, or len elements have been copied.
B
the type of the elements of the array.
xs
the array to fill.
start
the starting index of xs.
len
the maximal number of elements to copy.
returns
the number of elements written to the array
Definition Classes
IterableOnceOps
Note
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
def copyToArray[B >: A](xs: Array[B], start: Int): Int
Copy elements to an array, returning the number of elements written.
Copy elements to an array, returning the number of elements written.
Fills the given array xs starting at index start with values of this list.
Copying will stop once either all the elements of this list have been copied, or the end of the array is reached.
B
the type of the elements of the array.
xs
the array to fill.
start
the starting index of xs.
returns
the number of elements written to the array
Definition Classes
IterableOnceOps
Annotations
@deprecatedOverriding()
Note
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
def copyToArray[B >: A](xs: Array[B]): Int
Copy elements to an array, returning the number of elements written.
Copy elements to an array, returning the number of elements written.
Fills the given array xs starting at index start with values of this list.
Copying will stop once either all the elements of this list have been copied, or the end of the array is reached.
B
the type of the elements of the array.
xs
the array to fill.
returns
the number of elements written to the array
Definition Classes
IterableOnceOps
Annotations
@deprecatedOverriding()
Note
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
def corresponds[B](that: collection.Seq[B])(p: (A, B) => Boolean): Boolean
Tests whether every element of this list relates to the corresponding element of another sequence by satisfying a test predicate.
Tests whether every element of this list 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 list and y of that, otherwise false.
Definition Classes
List → SeqOps
def corresponds[B](that: IterableOnce[B])(p: (A, B) => Boolean): Boolean
Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.
Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.
B
the type of the elements of that
that
the other collection
p
the test predicate, which relates elements from both collections
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
Definition Classes
IterableOnceOps
def count(p: (A) => Boolean): Int
Counts the number of elements in the list which satisfy a predicate.
Counts the number of elements in the list which satisfy a predicate.
p
the predicate used to test elements.
returns
the number of elements satisfying the predicate p.
Definition Classes
IterableOnceOps
def diff[B >: A](that: collection.Seq[B]): List[A]
Computes the multiset difference between this list and another sequence.
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
StrictOptimizedSeqOps → SeqOps
def distinct: List[A]
Selects all the elements of this list ignoring the duplicates.
Selects all the elements of this list ignoring the duplicates.
returns
a new list consisting of all the elements of this list without duplicates.
Definition Classes
SeqOps
def distinctBy[B](f: (A) => B): List[A]
Selects all the elements of this list ignoring the duplicates as determined by == after applying the transforming function f.
Selects all the elements of this list ignoring the duplicates as determined by == after applying the transforming function f.
B
the type of the elements after being transformed by f
f
The transforming function whose result is used to determine the uniqueness of each element
returns
a new list consisting of all the elements of this list without duplicates.
Definition Classes
StrictOptimizedSeqOps → StrictOptimizedSeqOps → SeqOps
def drop(n: Int): List[A]
Selects all elements except first n ones.
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
StrictOptimizedLinearSeqOps → IterableOps → IterableOnceOps
def dropRight(n: Int): List[A]
The rest of the collection without its n last elements.
The rest of the collection without its n last elements. For linear, immutable collections this should avoid making a copy.
Note: Even when applied to a view or a lazy collection it will always force the elements.
n
the number of elements to drop from this list.
returns
a list consisting of all elements of this list except the last 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
StrictOptimizedIterableOps → IterableOps
def dropWhile(p: (A) => Boolean): List[A]
Drops longest prefix of elements that satisfy a predicate.
Drops longest prefix of elements that satisfy a predicate.
p
The predicate used to test elements.
returns
the longest suffix of this list whose first element does not satisfy the predicate p.
Definition Classes
StrictOptimizedLinearSeqOps → IterableOps → IterableOnceOps
def elementWise: ElementWiseExtractor[Int, A]
Returns an extractor object with a unapplySeq method, which extracts each element of a sequence data.
Returns an extractor object with a unapplySeq method, which extracts each element of a sequence data.
Definition Classes
PartialFunction
Example:
1. val firstChar: String => Option[Char] = _.headOption Seq("foo", "bar", "baz") match { case firstChar.unlift.elementWise(c0, c1, c2) => println(s"$c0, $c1, $c2") // Output: f, b, b }
def empty: List[A]
The empty iterable of the same type as this iterable
The empty iterable of the same type as this iterable
returns
an empty iterable of type C.
Definition Classes
IterableFactoryDefaults → IterableOps
def endsWith[B >: A](that: collection.Iterable[B]): Boolean
Tests whether this list ends with the given sequence.
Tests whether this list ends with the given sequence.
that
the sequence to test
returns
true if this list has that as a suffix, false otherwise.
Definition Classes
SeqOps
def ensuring(cond: (List[A]) => Boolean, msg: => Any): List[A]
Implicit
This member is added by an implicit conversion from List[A] toEnsuring[List[A]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: (List[A]) => Boolean): List[A]
Implicit
This member is added by an implicit conversion from List[A] toEnsuring[List[A]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: Boolean, msg: => Any): List[A]
Implicit
This member is added by an implicit conversion from List[A] toEnsuring[List[A]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: Boolean): List[A]
Implicit
This member is added by an implicit conversion from List[A] toEnsuring[List[A]] 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).
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(o: Any): Boolean
The universal equality method defined in AnyRef.
The universal equality method defined in AnyRef.
Definition Classes
List → Seq → Equals → AnyRef → Any
final def exists(p: (A) => Boolean): Boolean
Tests whether a predicate holds for at least one element of this list.
Tests whether a predicate holds for at least one element of this list.
p
the predicate used to test elements.
returns
true if the given predicate p is satisfied by at least one element of this list, otherwise false
Definition Classes
List → LinearSeqOps → IterableOnceOps
def filter(p: (A) => Boolean): List[A]
Selects all elements of this list which satisfy a predicate.
Selects all elements of this list which satisfy a predicate.
p
the predicate used to test elements.
returns
a new list consisting of all elements of this list that satisfy the given predicate p. The order of the elements is preserved.
Definition Classes
List → StrictOptimizedIterableOps → IterableOps → IterableOnceOps
def filterImpl(pred: (A) => Boolean, isFlipped: Boolean): List[A]
Attributes
protected[collection]
Definition Classes
StrictOptimizedIterableOps
def filterNot(p: (A) => Boolean): List[A]
Selects all elements of this list which do not satisfy a predicate.
Selects all elements of this list which do not satisfy a predicate.
returns
a new list consisting of all elements of this list that do not satisfy the given predicate pred. Their order may not be preserved.
Definition Classes
List → StrictOptimizedIterableOps → IterableOps → IterableOnceOps
def finalize(): Unit
Called by the garbage collector on the receiver object when there are no more references to the object.
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
final def find(p: (A) => Boolean): Option[A]
Finds the first element of the list satisfying a predicate, if any.
Finds the first element of the list satisfying a predicate, if any.
p
the predicate used to test elements.
returns
an option value containing the first element in the list that satisfies p, or None if none exists.
Definition Classes
List → LinearSeqOps → IterableOnceOps
def findLast(p: (A) => Boolean): Option[A]
Finds the last element of the list satisfying a predicate, if any.
Finds the last element of the list satisfying a predicate, if any.
p
the predicate used to test elements.
returns
an option value containing the last element in the list that satisfies p, or None if none exists.
Definition Classes
LinearSeqOps → SeqOps
final def flatMap[B](f: (A) => IterableOnce[B]): List[B]
Builds a new list by applying a function to all elements of this list and using the elements of the resulting collections.
Builds a new list 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: 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)
```
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
List → StrictOptimizedIterableOps → IterableOps → IterableOnceOps
def flatten[B](implicit toIterableOnce: (A) => IterableOnce[B]): List[B]
Converts this list of traversable collections into a list formed by the elements of these traversable collections.
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 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
StrictOptimizedIterableOps → IterableOps → IterableOnceOps
def fold[A1 >: A](z: A1)(op: (A1, A1) => A1): A1
Folds the elements of this list using the specified associative binary operator.
Folds the elements of this list 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.
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 list is empty.
Definition Classes
IterableOnceOps
def foldLeft[B](z: B)(op: (B, A) => B): B
Applies a binary operator to a start value and all elements of this list, going left to right.
Applies a binary operator to a start value and all elements of this list, going left to right.
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 left to right with the start value z on the left: op(...op(z, x₁), x₂, ..., x_n) where x₁, ..., x_n are the elements of this list. Returns z if this list is empty.
Definition Classes
LinearSeqOps → IterableOnceOps
final def foldRight[B](z: B)(op: (A, B) => B): B
Applies a binary operator to all elements of this list and a start value, going right to left.
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(x₁, op(x₂, ... op(x_n, z)...)) where x₁, ..., x_n are the elements of this list. Returns z if this list is empty.
Definition Classes
List → IterableOnceOps
final def forall(p: (A) => Boolean): Boolean
Tests whether a predicate holds for all elements of this list.
Tests whether a predicate holds for all elements of this list.
p
the predicate used to test elements.
returns
true if this list is empty or the given predicate p holds for all elements of this list, otherwise false.
Definition Classes
List → LinearSeqOps → IterableOnceOps
final def foreach[U](f: (A) => U): Unit
Apply f to each element for its side effects Note: [U] parameter needed to help scalac's type inference.
Apply f to each element for its side effects Note: [U] parameter needed to help scalac's type inference.
Definition Classes
List → LinearSeqOps → IterableOnceOps
Annotations
@inline()
def fromSpecific(coll: IterableOnce[A]): List[A]
Defines how to turn a given Iterable[A] into a collection of type C.
Defines how to turn a given Iterable[A] into a collection of type C.
This process can be done in a strict way or a non-strict way (ie. without evaluating the elements of the resulting collections). In other words, this methods defines the evaluation model of the collection.
Attributes
protected
Definition Classes
IterableFactoryDefaults → IterableOps
Note
When implementing a custom collection type and refining C to the new type, this method needs to be overridden (the compiler will issue an error otherwise). In the common case where C =:= CC[A], this can be done by mixing in the scala.collection.IterableFactoryDefaults trait, which implements the method using iterableFactory.
,
As witnessed by the @uncheckedVariance annotation, using this method might be unsound. However, as long as it is called with an Iterable[A] obtained from this collection (as it is the case in the implementations of operations where we use a View[A]), it is safe.
final def getClass(): Class[_ <: AnyRef]
Returns the runtime class representation of the object.
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: (A) => K): Map[K, List[A]]
Partitions this list into a map of lists according to some discriminator function.
Partitions this list into a map of lists according to some discriminator function.
Note: Even when applied to a view or a lazy collection it will always force the elements.
K
the type of keys returned by the discriminator function.
f
the discriminator function.
returns
A map from keys to lists 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 list of those elements x for which f(x) equals k.
Definition Classes
IterableOps
def groupMap[K, B](key: (A) => K)(f: (A) => B): Map[K, List[B]]
Partitions this list into a map of lists according to a discriminator function key.
Partitions this list into a map of lists according to a discriminator function key. Each element in a group is transformed into a value of type B using the value function.
It is equivalent to groupBy(key).mapValues(_.map(f)), but more efficient.
```
case class User(name: String, age: Int)

def namesByAge(users: Seq[User]): Map[Int, Seq[String]] =
  users.groupMap(_.age)(_.name)
```
Note: Even when applied to a view or a lazy collection it will always force the elements.
K
the type of keys returned by the discriminator function
B
the type of values returned by the transformation function
key
the discriminator function
f
the element transformation function
Definition Classes
IterableOps
def groupMapReduce[K, B](key: (A) => K)(f: (A) => B)(reduce: (B, B) => B): Map[K, B]
Partitions this list into a map according to a discriminator function key.
Partitions this list into a map according to a discriminator function key. All the values that have the same discriminator are then transformed by the f function and then reduced into a single value with the reduce function.
It is equivalent to groupBy(key).mapValues(_.map(f).reduce(reduce)), but more efficient.
```
def occurrences[A](as: Seq[A]): Map[A, Int] =
  as.groupMapReduce(identity)(_ => 1)(_ + _)
```
Note: Even when applied to a view or a lazy collection it will always force the elements.
Definition Classes
IterableOps
def grouped(size: Int): Iterator[List[A]]
Partitions elements in fixed size lists.
Partitions elements in fixed size lists.
size
the number of elements per group
returns
An iterator producing lists of size size, except the last will be less than size size if the elements don't divide evenly.
Definition Classes
IterableOps
See also
scala.collection.Iterator, method grouped
def hashCode(): Int
The hashCode method for reference types.
The hashCode method for reference types. See hashCode in scala.Any.
returns
the hash code value for this object.
Definition Classes
Seq → AnyRef → Any
def head: A
Selects the first element of this list.
Selects the first element of this list.
returns
the first element of this list.
Definition Classes
IterableOps
Exceptions thrown
NoSuchElementException if the list is empty.
def headOption: Option[A]
Optionally selects the first element.
Optionally selects the first element.
returns
the first element of this list if it is nonempty, None if it is empty.
Definition Classes
LinearSeqOps → IterableOps
def indexOf[B >: A](elem: B): Int
Finds index of first occurrence of some value in this list.
Finds index of first occurrence of some value in this list.
B
the type of the element elem.
elem
the element value to search for.
returns
the index >= 0 of the first element of this list that is equal (as determined by ==) to elem, or -1, if none exists.
Definition Classes
SeqOps
Annotations
@deprecatedOverriding()
def indexOf[B >: A](elem: B, from: Int): Int
Finds index of first occurrence of some value in this list after or at some start index.
Finds index of first occurrence of some value in this list after or at some start index.
B
the type of the element elem.
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
SeqOps
def indexOfSlice[B >: A](that: collection.Seq[B]): Int
Finds first index where this list contains a given sequence as a slice.
Finds first index where this list contains a given sequence as a slice.
that
the sequence to test
returns
the first index >= 0 such that the elements of this list starting at this index match the elements of sequence that, or -1 if no such subsequence exists.
Definition Classes
SeqOps
Annotations
@deprecatedOverriding()
def indexOfSlice[B >: A](that: collection.Seq[B], from: Int): Int
Finds first index after or at a start index where this list contains a given sequence as a slice.
Finds first index after or at a start index where this list contains a given sequence as a slice.
that
the sequence to test
from
the start index
returns
the first index >= from such that the elements of this list starting at this index match the elements of sequence that, or -1 if no such subsequence exists.
Definition Classes
SeqOps
def indexWhere(p: (A) => Boolean, from: Int): Int
Finds index of the first element satisfying some predicate after or at some start index.
Finds index of the first element satisfying some predicate after or at some start index.
p
the predicate used to test elements.
from
the start index
returns
the index >= from of the first element of this list that satisfies the predicate p, or -1, if none exists.
Definition Classes
LinearSeqOps → SeqOps
def indexWhere(p: (A) => Boolean): Int
Finds index of the first element satisfying some predicate.
Finds index of the first element satisfying some predicate.
p
the predicate used to test elements.
returns
the index >= 0 of the first element of this list that satisfies the predicate p, or -1, if none exists.
Definition Classes
SeqOps
Annotations
@deprecatedOverriding()
def indices: Range
Produces the range of all indices of this sequence.
Produces the range of all indices of this sequence.
Note: Even when applied to a view or a lazy collection it will always force the elements.
returns
a Range value from 0 to one less than the length of this list.
Definition Classes
SeqOps
def init: List[A]
The initial part of the collection without its last element.
The initial part of the collection without its last element.
Note: Even when applied to a view or a lazy collection it will always force the elements.
Definition Classes
IterableOps
def inits: Iterator[List[A]]
Iterates over the inits of this list.
Iterates over the inits of this list. The first value will be this list and the final one will be an empty list, with the intervening values the results of successive applications of init.
Note: Even when applied to a view or a lazy collection it will always force the elements.
returns
an iterator over all the inits of this list
Definition Classes
IterableOps
Example:
1. List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)
def intersect[B >: A](that: collection.Seq[B]): List[A]
Computes the multiset intersection between this list and another sequence.
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
StrictOptimizedSeqOps → SeqOps
def isDefinedAt(x: Int): Boolean
Tests whether this list contains given index.
Tests whether this list contains given index.
The implementations of methods apply and isDefinedAt turn a Seq[A] into a PartialFunction[Int, A].
returns
true if this list contains an element at position idx, false otherwise.
Definition Classes
LinearSeqOps → SeqOps
final def isEmpty: Boolean
<invalid inheritdoc annotation>
<invalid inheritdoc annotation>
Note: *Must* be overridden in subclasses. The default implementation that is inherited from SeqOps uses lengthCompare, which is defined here to use isEmpty.
Definition Classes
List → LinearSeqOps → SeqOps → IterableOnceOps
final def isInstanceOf[T0]: Boolean
Test whether the dynamic type of the receiver object has the same erasure as T0.
Test whether the dynamic type of the receiver object has the same erasure as T0.
Depending on what T0 is, the test is done in one of the below ways:
- T0 is a non-parameterized class type, e.g. BigDecimal: this method returns true if the value of the receiver object is a BigDecimal or a subtype of BigDecimal.
- T0 is a parameterized class type, e.g. List[Int]: this method returns true if the value of the receiver object is some List[X] for any X. For example, List(1, 2, 3).isInstanceOf[List[String]] will return true.
- T0 is some singleton type x.type or literal x: this method returns this.eq(x). For example, x.isInstanceOf[1] is equivalent to x.eq(1)
- T0 is an intersection X with Y or X & Y: this method is equivalent to x.isInstanceOf[X] && x.isInstanceOf[Y]
- T0 is a union X | Y: this method is equivalent to x.isInstanceOf[X] || x.isInstanceOf[Y]
- T0 is a type parameter or an abstract type member: this method is equivalent to isInstanceOf[U] where U is T0's upper bound, Any if T0 is unbounded. For example, x.isInstanceOf[A] where A is an unbounded type parameter will return true for any value of x.
This is exactly equivalent to the type pattern _: T0
returns
true if the receiver object is an instance of erasure of type T0; false otherwise.
Definition Classes
Any
Note
due to the unexpectedness of List(1, 2, 3).isInstanceOf[List[String]] returning true and x.isInstanceOf[A] where A is a type parameter or abstract member returning true, these forms issue a warning.
def isTraversableAgain: Boolean
Tests whether this list can be repeatedly traversed.
Tests whether this list can be repeatedly traversed. Always true for Iterables and false for Iterators unless overridden.
returns
true if it is repeatedly traversable, false otherwise.
Definition Classes
IterableOps → IterableOnceOps
def iterableFactory: SeqFactory[List]
The companion object of this list, providing various factory methods.
The companion object of this list, providing various factory methods.
Definition Classes
List → LinearSeq → LinearSeq → Seq → Iterable → Seq → Iterable → IterableOps
Note
When implementing a custom collection type and refining CC to the new type, this method needs to be overridden to return a factory for the new type (the compiler will issue an error otherwise).
def iterator: Iterator[A]
Iterator can be used only once
Iterator can be used only once
Definition Classes
StrictOptimizedLinearSeqOps → LinearSeqOps → IterableOnce
def knownSize: Int
returns
The number of elements in this list, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.
Definition Classes
IterableOnce
def last: A
Selects the last element.
Selects the last element.
returns
The last element of this list.
Definition Classes
List → LinearSeqOps → IterableOps
Exceptions thrown
NoSuchElementException If the list is empty.
def lastIndexOf[B >: A](elem: B, end: Int = length - 1): Int
Finds index of last occurrence of some value in this list before or at a given end index.
Finds index of last occurrence of some value in this list before or at a given end index.
B
the type of the element elem.
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
SeqOps
def lastIndexOfSlice[B >: A](that: collection.Seq[B]): Int
Finds last index where this list contains a given sequence as a slice.
Finds last index where this list contains a given sequence as a slice.
that
the sequence to test
returns
the last index such that the elements of this list starting at this index match the elements of sequence that, or -1 if no such subsequence exists.
Definition Classes
SeqOps
Annotations
@deprecatedOverriding()
def lastIndexOfSlice[B >: A](that: collection.Seq[B], end: Int): Int
Finds last index before or at a given end index where this list contains a given sequence as a slice.
Finds last index before or at a given end index where this list 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 list starting at this index match the elements of sequence that, or -1 if no such subsequence exists.
Definition Classes
SeqOps
def lastIndexWhere(p: (A) => Boolean, end: Int): Int
Finds index of last element satisfying some predicate before or at given end index.
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 list that satisfies the predicate p, or -1, if none exists.
Definition Classes
LinearSeqOps → SeqOps
def lastIndexWhere(p: (A) => Boolean): Int
Finds index of last element satisfying some predicate.
Finds index of last element satisfying some predicate.
p
the predicate used to test elements.
returns
the index of the last element of this list that satisfies the predicate p, or -1, if none exists.
Definition Classes
SeqOps
Annotations
@deprecatedOverriding()
def lastOption: Option[A]
Optionally selects the last element.
Optionally selects the last element.
returns
the last element of this list$ if it is nonempty, None if it is empty.
Definition Classes
IterableOps
def lazyZip[B](that: collection.Iterable[B]): LazyZip2[A, B, List.this.type]
Analogous to zip except that the elements in each collection are not consumed until a strict operation is invoked on the returned LazyZip2 decorator.
Analogous to zip except that the elements in each collection are not consumed until a strict operation is invoked on the returned LazyZip2 decorator.
Calls to lazyZip can be chained to support higher arities (up to 4) without incurring the expense of constructing and deconstructing intermediary tuples.
```
val xs = List(1, 2, 3)
val res = (xs lazyZip xs lazyZip xs lazyZip xs).map((a, b, c, d) => a + b + c + d)
// res == List(4, 8, 12)
```
B
the type of the second element in each eventual pair
that
the iterable providing the second element of each eventual pair
returns
a decorator LazyZip2 that allows strict operations to be performed on the lazily evaluated pairs or chained calls to lazyZip. Implicit conversion to Iterable[(A, B)] is also supported.
Definition Classes
Iterable
final def length: Int
The length (number of elements) of the list.
The length (number of elements) of the list. size is an alias for length in Seq collections.
Definition Classes
List → LinearSeqOps → SeqOps
final def lengthCompare(len: Int): Int
Compares the length of this list to a test value.
Compares the length of this list 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 overridden if computing length is cheap and knownSize returns -1.
Definition Classes
List → LinearSeqOps → SeqOps
See also
lengthIs
def lengthCompare(that: collection.Iterable[_]): Int
Compares the length of this list to the size of another Iterable.
Compares the length of this list to the size of another Iterable.
that
the Iterable whose size is compared with this list's length.
returns
A value x where
```
x <  0       if this.length <  that.size
x == 0       if this.length == that.size
x >  0       if this.length >  that.size
```
The method as implemented here does not call length or size directly; its running time is O(this.length min that.size) instead of O(this.length + that.size). The method should be overridden if computing size is cheap and knownSize returns -1.
Definition Classes
LinearSeqOps → SeqOps
final def lengthIs: SizeCompareOps
Returns a value class containing operations for comparing the length of this list to a test value.
Returns a value class containing operations for comparing the length of this list to a test value.
These operations are implemented in terms of lengthCompare(Int), and allow the following more readable usages:
```
this.lengthIs < len     // this.lengthCompare(len) < 0
this.lengthIs <= len    // this.lengthCompare(len) <= 0
this.lengthIs == len    // this.lengthCompare(len) == 0
this.lengthIs != len    // this.lengthCompare(len) != 0
this.lengthIs >= len    // this.lengthCompare(len) >= 0
this.lengthIs > len     // this.lengthCompare(len) > 0
```
Definition Classes
SeqOps
Annotations
@inline()
def lift: (Int) => Option[A]
Turns this partial function into a plain function returning an Option result.
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]
Builds a new list by applying a function to all elements of this list.
Builds a new list by applying a function to all elements of this list.
B
the element type of the returned list.
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
List → StrictOptimizedIterableOps → IterableOps → IterableOnceOps
final def mapConserve[B >: A <: AnyRef](f: (A) => B): List[B]
Builds a new list by applying a function to all elements of this list.
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).
B
the element type of the returned collection.
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.
Annotations
@inline()
def max[B >: A](implicit ord: math.Ordering[B]): A
Finds the largest element.
Finds the largest element.
B
The type over which the ordering is defined.
ord
An ordering to be used for comparing elements.
returns
the largest element of this list with respect to the ordering ord.
Definition Classes
IterableOnceOps
Exceptions thrown
UnsupportedOperationException if this list is empty.
def maxBy[B](f: (A) => B)(implicit cmp: math.Ordering[B]): A
Finds the first element which yields the largest value measured by function f.
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.
cmp
An ordering to be used for comparing elements.
returns
the first element of this list with the largest value measured by function f with respect to the ordering cmp.
Definition Classes
IterableOnceOps
Exceptions thrown
UnsupportedOperationException if this list is empty.
def maxByOption[B](f: (A) => B)(implicit cmp: math.Ordering[B]): Option[A]
Finds the first element which yields the largest value measured by function f.
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.
cmp
An ordering to be used for comparing elements.
returns
an option value containing the first element of this list with the largest value measured by function f with respect to the ordering cmp.
Definition Classes
IterableOnceOps
def maxOption[B >: A](implicit ord: math.Ordering[B]): Option[A]
Finds the largest element.
Finds the largest element.
B
The type over which the ordering is defined.
ord
An ordering to be used for comparing elements.
returns
an option value containing the largest element of this list with respect to the ordering ord.
Definition Classes
IterableOnceOps
def min[B >: A](implicit ord: math.Ordering[B]): A
Finds the smallest element.
Finds the smallest element.
B
The type over which the ordering is defined.
ord
An ordering to be used for comparing elements.
returns
the smallest element of this list with respect to the ordering ord.
Definition Classes
IterableOnceOps
Exceptions thrown
UnsupportedOperationException if this list is empty.
def minBy[B](f: (A) => B)(implicit cmp: math.Ordering[B]): A
Finds the first element which yields the smallest value measured by function f.
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.
cmp
An ordering to be used for comparing elements.
returns
the first element of this list with the smallest value measured by function f with respect to the ordering cmp.
Definition Classes
IterableOnceOps
Exceptions thrown
UnsupportedOperationException if this list is empty.
def minByOption[B](f: (A) => B)(implicit cmp: math.Ordering[B]): Option[A]
Finds the first element which yields the smallest value measured by function f.
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.
cmp
An ordering to be used for comparing elements.
returns
an option value containing the first element of this list with the smallest value measured by function f with respect to the ordering cmp.
Definition Classes
IterableOnceOps
def minOption[B >: A](implicit ord: math.Ordering[B]): Option[A]
Finds the smallest element.
Finds the smallest element.
B
The type over which the ordering is defined.
ord
An ordering to be used for comparing elements.
returns
an option value containing the smallest element of this list with respect to the ordering ord.
Definition Classes
IterableOnceOps
final def mkString: String
Displays all elements of this list in a string.
Displays all elements of this list in a string.
Delegates to addString, which can be overridden.
returns
a string representation of this list. In the resulting string the string representations (w.r.t. the method toString) of all elements of this list follow each other without any separator string.
Definition Classes
IterableOnceOps
Annotations
@inline()
final def mkString(sep: String): String
Displays all elements of this list in a string using a separator string.
Displays all elements of this list in a string using a separator string.
Delegates to addString, which can be overridden.
sep
the separator string.
returns
a string representation of this list. In the resulting string the string representations (w.r.t. the method toString) of all elements of this list are separated by the string sep.
Definition Classes
IterableOnceOps
Annotations
@inline()
Example:
1. List(1, 2, 3).mkString("|") = "1|2|3"
final def mkString(start: String, sep: String, end: String): String
Displays all elements of this list in a string using start, end, and separator strings.
Displays all elements of this list in a string using start, end, and separator strings.
Delegates to addString, which can be overridden.
start
the starting string.
sep
the separator string.
end
the ending string.
returns
a string representation of this list. 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 list are separated by the string sep.
Definition Classes
IterableOnceOps
Example:
1. List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
final def ne(arg0: AnyRef): Boolean
Equivalent to !(this eq that).
Equivalent to !(this eq that).
returns
true if the argument is not a reference to the receiver object; false otherwise.
Definition Classes
AnyRef
def newSpecificBuilder: Builder[A, List[A]]
returns
a strict builder for the same collection type. Note that in the case of lazy collections (e.g. scala.collection.View or scala.collection.immutable.LazyList), it is possible to implement this method but the resulting Builder will break laziness. As a consequence, operations should preferably be implemented with fromSpecific instead of this method.
Attributes
protected
Definition Classes
IterableFactoryDefaults → IterableOps
Note
When implementing a custom collection type and refining C to the new type, this method needs to be overridden (the compiler will issue an error otherwise). In the common case where C =:= CC[A], this can be done by mixing in the scala.collection.IterableFactoryDefaults trait, which implements the method using iterableFactory.
,
As witnessed by the @uncheckedVariance annotation, using this method might be unsound. However, as long as the returned builder is only fed with A values taken from this instance, it is safe.
def nonEmpty: Boolean
Tests whether the list is not empty.
Tests whether the list is not empty.
returns
true if the list contains at least one element, false otherwise.
Definition Classes
IterableOnceOps
Annotations
@deprecatedOverriding()
final def notify(): Unit
Wakes up a single thread that is waiting on the receiver object's monitor.
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.
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 occCounts[B](sq: collection.Seq[B]): mutable.Map[B, Int]
Attributes
protected[collection]
Definition Classes
SeqOps
def orElse[A1 <: Int, B1 >: A](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.
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[B >: A](len: Int, elem: B): List[B]
A copy of this list with an element value appended until a given target length is reached.
A copy of this list with an element value appended until a given target length is reached.
B
the element type of the returned list.
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 collection has a length of at least len.
Definition Classes
StrictOptimizedSeqOps → SeqOps
def partition(p: (A) => Boolean): (List[A], List[A])
A pair of, first, all elements that satisfy predicate p and, second, all elements that do not.
A pair of, first, all elements that satisfy predicate p and, second, all elements that do not. Interesting because it splits a collection in two.
The default implementation provided here needs to traverse the collection twice. Strict collections have an overridden version of partition in StrictOptimizedIterableOps, which requires only a single traversal.
Definition Classes
List → StrictOptimizedIterableOps → IterableOps
def partitionMap[A1, A2](f: (A) => Either[A1, A2]): (List[A1], List[A2])
Applies a function f to each element of the list and returns a pair of lists: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.
Applies a function f to each element of the list and returns a pair of lists: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.
Example:
```
val xs = `List`(1, "one", 2, "two", 3, "three") partitionMap {
 case i: Int => Left(i)
 case s: String => Right(s)
}
// xs == (`List`(1, 2, 3),
//        `List`(one, two, three))
```
A1
the element type of the first resulting collection
A2
the element type of the second resulting collection
f
the 'split function' mapping the elements of this list to an scala.util.Either
returns
a pair of lists: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.
Definition Classes
StrictOptimizedIterableOps → IterableOps
def patch[B >: A](from: Int, other: IterableOnce[B], replaced: Int): List[B]
Produces a new list where a slice of elements in this list is replaced by another sequence.
Produces a new list where a slice of elements in this list is replaced by another sequence.
Patching at negative indices is the same as patching starting at 0. Patching at indices at or larger than the length of the original list appends the patch to the end. If more values are replaced than actually exist, the excess is ignored.
B
the element type of the returned list.
from
the index of the first replaced element
other
the replacement sequence
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 all the elements of other.
Definition Classes
StrictOptimizedSeqOps → SeqOps
def permutations: Iterator[List[A]]
Iterates over distinct permutations of elements.
Iterates over distinct permutations of elements.
Note: Even when applied to a view or a lazy collection it will always force the elements.
returns
An Iterator which traverses the distinct permutations of this list.
Definition Classes
SeqOps
Example:
1. Seq('a', 'b', 'b').permutations.foreach(println) // List(a, b, b) // List(b, a, b) // List(b, b, a)
def prepended[B >: A](elem: B): List[B]
A copy of the list with an element prepended.
A copy of the list with an element prepended.
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)
```
B
the element type of the returned list.
elem
the prepended element
returns
a new list consisting of value followed by all elements of this list.
Definition Classes
List → StrictOptimizedSeqOps → SeqOps
def prependedAll[B >: A](prefix: IterableOnce[B]): List[B]
As with :++, returns a new collection containing the elements from the left operand followed by the elements from the right operand.
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.
B
the element type of the returned collection.
prefix
the iterable to prepend.
returns
a new list which contains all elements of prefix followed by all the elements of this list.
Definition Classes
List → StrictOptimizedSeqOps → SeqOps
def product[B >: A](implicit num: math.Numeric[B]): B
Multiplies up the elements of this collection.
Multiplies up the elements of this collection.
B
the result type of the * operator.
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 list with respect to the * operator in num.
Definition Classes
IterableOnceOps
def reduce[B >: A](op: (B, B) => B): B
Reduces the elements of this list using the specified associative binary operator.
Reduces the elements of this list using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
B
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 list is nonempty.
Definition Classes
IterableOnceOps
Exceptions thrown
UnsupportedOperationException if this list is empty.
def reduceLeft[B >: A](op: (B, A) => B): B
Applies a binary operator to all elements of this list, going left to right.
Applies a binary operator to all elements of this list, going left to right.
B
the result type of the binary operator.
op
the binary operator.
returns
the result of inserting op between consecutive elements of this list, going left to right: op( op( ... op(x₁, x₂) ..., x_n-1), x_n) where x₁, ..., x_n are the elements of this list.
Definition Classes
IterableOnceOps
Exceptions thrown
UnsupportedOperationException if this list is empty.
def reduceLeftOption[B >: A](op: (B, A) => B): Option[B]
Optionally applies a binary operator to all elements of this list, going left to right.
Optionally applies a binary operator to all elements of this list, going left to right.
B
the result type of the binary operator.
op
the binary operator.
returns
an option value containing the result of reduceLeft(op) if this list is nonempty, None otherwise.
Definition Classes
IterableOnceOps
def reduceOption[B >: A](op: (B, B) => B): Option[B]
Reduces the elements of this list, if any, using the specified associative binary operator.
Reduces the elements of this list, if any, using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
B
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
IterableOnceOps
def reduceRight[B >: A](op: (A, B) => B): B
Applies a binary operator to all elements of this list, going right to left.
Applies a binary operator to all elements of this list, going right to left.
B
the result type of the binary operator.
op
the binary operator.
returns
the result of inserting op between consecutive elements of this list, going right to left: op(x₁, op(x₂, ..., op(x_n-1, x_n)...)) where x₁, ..., x_n are the elements of this list.
Definition Classes
IterableOnceOps
Exceptions thrown
UnsupportedOperationException if this list is empty.
def reduceRightOption[B >: A](op: (A, B) => B): Option[B]
Optionally applies a binary operator to all elements of this list, going right to left.
Optionally applies a binary operator to all elements of this list, going right to left.
B
the result type of the binary operator.
op
the binary operator.
returns
an option value containing the result of reduceRight(op) if this list is nonempty, None otherwise.
Definition Classes
IterableOnceOps
final def reverse: List[A]
Returns new list with elements in reversed order.
Returns new list with elements in reversed order.
Note: Even when applied to a view or a lazy collection it will always force the elements.
returns
A new list with all elements of this list in reversed order.
Definition Classes
List → SeqOps
def reverseIterator: Iterator[A]
An iterator yielding elements in reversed order.
An iterator yielding elements in reversed order.
Note: xs.reverseIterator is the same as xs.reverse.iterator but might be more efficient.
returns
an iterator yielding the elements of this list in reversed order
Definition Classes
SeqOps
def reverse_:::[B >: A](prefix: List[B]): List[B]
Adds the elements of a given list in reverse order in front of this list.
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.
def reversed: collection.Iterable[A]
Attributes
protected
Definition Classes
IterableOnceOps
def runWith[U](action: (A) => U): (Int) => Boolean
Composes this partial function with an action function which gets applied to results of this partial function.
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
See also
applyOrElse.
def sameElements[B >: A](that: IterableOnce[B]): Boolean
Are the elements of this collection the same (and in the same order) as those of that?
Are the elements of this collection the same (and in the same order) as those of that?
Definition Classes
LinearSeqOps → SeqOps
def scan[B >: A](z: B)(op: (B, B) => B): List[B]
Computes a prefix scan of the elements of the collection.
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
z
neutral element for the operator op
op
the associative operator for the scan
returns
a new list containing the prefix scan of the elements in this list
Definition Classes
IterableOps
def scanLeft[B](z: B)(op: (B, A) => B): List[B]
Produces a list containing cumulative results of applying the operator going left to right, including the initial value.
Produces a list containing cumulative results of applying the operator going left to right, including the initial value.
B
the type of the elements in the resulting collection
z
the initial value
op
the binary operator applied to the intermediate result and the element
returns
collection with intermediate results
Definition Classes
StrictOptimizedIterableOps → IterableOps → IterableOnceOps
def scanRight[B](z: B)(op: (A, B) => B): List[B]
Produces a collection containing cumulative results of applying the operator going right to left.
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: Even when applied to a view or a lazy collection it will always force the elements.
Example:
```
List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)
```
B
the type of the elements in the resulting collection
z
the initial value
op
the binary operator applied to the intermediate result and the element
returns
collection with intermediate results
Definition Classes
IterableOps
def search[B >: A](elem: B, from: Int, to: Int)(implicit ord: Ordering[B]): SearchResult
Search within an interval in this sorted sequence for a specific element.
Search within an interval in this sorted sequence for a specific element. If this sequence is an IndexedSeq, a binary search is used. Otherwise, a linear search is used.
The sequence should be sorted with the same Ordering before calling; otherwise, the results are undefined.
elem
the element to find.
from
the index where the search starts.
to
the index following where the search ends.
ord
the ordering to be used to compare elements.
returns
a Found value containing the index corresponding to the element in the sequence, or the InsertionPoint where the element would be inserted if the element is not in the sequence.
Definition Classes
SeqOps
Note
if to <= from, the search space is empty, and an InsertionPoint at from is returned
See also
scala.collection.IndexedSeq
scala.math.Ordering
scala.collection.SeqOps, method sorted
def search[B >: A](elem: B)(implicit ord: Ordering[B]): SearchResult
Search this sorted sequence for a specific element.
Search this sorted sequence for a specific element. If the sequence is an IndexedSeq, a binary search is used. Otherwise, a linear search is used.
The sequence should be sorted with the same Ordering before calling; otherwise, the results are undefined.
elem
the element to find.
ord
the ordering to be used to compare elements.
returns
a Found value containing the index corresponding to the element in the sequence, or the InsertionPoint where the element would be inserted if the element is not in the sequence.
Definition Classes
SeqOps
See also
scala.collection.IndexedSeq
scala.math.Ordering
scala.collection.SeqOps, method sorted
def segmentLength(p: (A) => Boolean, from: Int): Int
Computes the length of the longest segment that starts from some index and whose elements all satisfy some predicate.
Computes the length of the longest segment that starts from some index and whose elements all satisfy some predicate.
p
the predicate used to test elements.
from
the index where the search starts.
returns
the length of the longest segment of this list starting from index from such that every element of the segment satisfies the predicate p.
Definition Classes
LinearSeqOps → SeqOps
final def segmentLength(p: (A) => Boolean): Int
Computes the length of the longest segment that starts from the first element and whose elements all satisfy some predicate.
Computes the length of the longest segment that starts from the first element and whose elements all satisfy some predicate.
p
the predicate used to test elements.
returns
the length of the longest segment of this list that starts from the first element such that every element of the segment satisfies the predicate p.
Definition Classes
SeqOps
final def size: Int
The size of this list.
The size of this list.
returns
the number of elements in this list.
Definition Classes
SeqOps → IterableOnceOps
final def sizeCompare(that: collection.Iterable[_]): Int
Compares the size of this list to the size of another Iterable.
Compares the size of this list to the size of another Iterable.
that
the Iterable whose size is compared with this list's size.
returns
A value x where
```
x <  0       if this.size <  that.size
x == 0       if this.size == that.size
x >  0       if this.size >  that.size
```
The method as implemented here does not call size directly; its running time is O(this.size min that.size) instead of O(this.size + that.size). The method should be overridden if computing size is cheap and knownSize returns -1.
Definition Classes
SeqOps → IterableOps
final def sizeCompare(otherSize: Int): Int
Compares the size of this list to a test value.
Compares the size of this list to a test value.
otherSize
the test value that gets compared with the size.
returns
A value x where
```
x <  0       if this.size <  otherSize
x == 0       if this.size == otherSize
x >  0       if this.size >  otherSize
```
The method as implemented here does not call size directly; its running time is O(size min otherSize) instead of O(size). The method should be overridden if computing size is cheap and knownSize returns -1.
Definition Classes
SeqOps → IterableOps
See also
sizeIs
final def sizeIs: SizeCompareOps
Returns a value class containing operations for comparing the size of this list to a test value.
Returns a value class containing operations for comparing the size of this list to a test value.
These operations are implemented in terms of sizeCompare(Int), and allow the following more readable usages:
```
this.sizeIs < size     // this.sizeCompare(size) < 0
this.sizeIs <= size    // this.sizeCompare(size) <= 0
this.sizeIs == size    // this.sizeCompare(size) == 0
this.sizeIs != size    // this.sizeCompare(size) != 0
this.sizeIs >= size    // this.sizeCompare(size) >= 0
this.sizeIs > size     // this.sizeCompare(size) > 0
```
Definition Classes
IterableOps
Annotations
@inline()
def slice(from: Int, until: Int): List[A]
from
the lowest index to include from this list.
until
the lowest index to EXCLUDE from this list.
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
List → IterableOps → IterableOnceOps
Example:
1. // 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[A]]
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
The returned iterator will be empty when called on an empty collection. The last element the iterator produces may be smaller than the window size when the original collection isn't exhausted by the window before it and its last element isn't skipped by the step before it.
size
the number of elements per group
step
the distance between the first elements of successive groups
returns
An iterator producing lists of size size, except the last element (which may be the only element) will be smaller if there are fewer than size elements remaining to be grouped.
Definition Classes
IterableOps
Examples:
1. List(1, 2, 3, 4, 5).sliding(2, 2) = Iterator(List(1, 2), List(3, 4), List(5))
2. List(1, 2, 3, 4, 5, 6).sliding(2, 3) = Iterator(List(1, 2), List(4, 5))
See also
scala.collection.Iterator, method sliding
def sliding(size: Int): Iterator[List[A]]
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
An empty collection returns an empty iterator, and a non-empty collection containing fewer elements than the window size returns an iterator that will produce the original collection as its only element.
size
the number of elements per group
returns
An iterator producing lists of size size, except for a non-empty collection with less than size elements, which returns an iterator that produces the source collection itself as its only element.
Definition Classes
IterableOps
Examples:
1. List().sliding(2) = empty iterator
2. List(1).sliding(2) = Iterator(List(1))
3. List(1, 2).sliding(2) = Iterator(List(1, 2))
4. List(1, 2, 3).sliding(2) = Iterator(List(1, 2), List(2, 3))
See also
scala.collection.Iterator, method sliding
def sortBy[B](f: (A) => B)(implicit ord: Ordering[B]): List[A]
Sorts this list according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.
Sorts this list according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.
Note: Even when applied to a view or a lazy collection it will always force the elements.
The sort is stable. That is, elements that are equal (as determined by ord.compare) appear in the same order in the sorted sequence as in the original.
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 list consisting of the elements of this list sorted according to the ordering where x < y if ord.lt(f(x), f(y)).
Definition Classes
SeqOps
Example:
1. 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
def sortWith(lt: (A, A) => Boolean): List[A]
Sorts this list according to a comparison function.
Sorts this list according to a comparison function.
Note: Even when applied to a view or a lazy collection it will always force the elements.
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 list consisting of the elements of this list sorted according to the comparison function lt.
Definition Classes
SeqOps
Example:
1. List("Steve", "Tom", "John", "Bob").sortWith(_.compareTo(_) < 0) = List("Bob", "John", "Steve", "Tom")
def sorted[B >: A](implicit ord: Ordering[B]): List[A]
Sorts this list according to an Ordering.
Sorts this list according to an Ordering.
The sort is stable. That is, elements that are equal (as determined by ord.compare) appear in the same order in the sorted sequence as in the original.
ord
the ordering to be used to compare elements.
returns
a list consisting of the elements of this list sorted according to the ordering ord.
Definition Classes
StrictOptimizedSeqOps → SeqOps
See also
scala.math.Ordering Note: Even when applied to a view or a lazy collection it will always force the elements.
final def span(p: (A) => Boolean): (List[A], List[A])
Splits this list into a prefix/suffix pair according to a predicate.
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.
p
the test predicate
returns
a pair consisting of the longest prefix of this list whose elements all satisfy p, and the rest of this list.
Definition Classes
List → StrictOptimizedIterableOps → IterableOps → IterableOnceOps
Annotations
@inline()
def splitAt(n: Int): (List[A], List[A])
Splits this list into a prefix/suffix pair at a given position.
Splits this list 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).
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
List → IterableOps → IterableOnceOps
def startsWith[B >: A](that: IterableOnce[B], offset: Int = 0): Boolean
Tests whether this list contains the given sequence at a given index.
Tests whether this list 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 list at index offset, otherwise false.
Definition Classes
SeqOps
def stepper[S <: Stepper[_]](implicit shape: StepperShape[A, S]): S
Returns a scala.collection.Stepper for the elements of this collection.
Returns a scala.collection.Stepper for the elements of this collection.
The Stepper enables creating a Java stream to operate on the collection, see scala.jdk.StreamConverters. For collections holding primitive values, the Stepper can be used as an iterator which doesn't box the elements.
The implicit scala.collection.StepperShape parameter defines the resulting Stepper type according to the element type of this collection.
- For collections of Int, Short, Byte or Char, an scala.collection.IntStepper is returned
- For collections of Double or Float, a scala.collection.DoubleStepper is returned
- For collections of Long a scala.collection.LongStepper is returned
- For any other element type, an scala.collection.AnyStepper is returned
Note that this method is overridden in subclasses and the return type is refined to S with EfficientSplit, for example scala.collection.IndexedSeqOps.stepper. For Steppers marked with scala.collection.Stepper.EfficientSplit, the converters in scala.jdk.StreamConverters allow creating parallel streams, whereas bare Steppers can be converted only to sequential streams.
Definition Classes
IterableOnce
final def strictOptimizedCollect[B, C2](b: Builder[B, C2], pf: PartialFunction[A, B]): C2
B
Type of elements of the resulting collection (e.g. String)
C2
Type of the resulting collection (e.g. List[String])
b
Builder to use to build the resulting collection
pf
Element transformation partial function
returns
The resulting collection
Attributes
protected[this]
Definition Classes
StrictOptimizedIterableOps
Annotations
@inline()
final def strictOptimizedConcat[B >: A, C2](that: IterableOnce[B], b: Builder[B, C2]): C2
B
Type of elements of the resulting collections (e.g. Int)
C2
Type of the resulting collection (e.g. List[Int])
that
Elements to concatenate to this collection
b
Builder to use to build the resulting collection
returns
The resulting collection
Attributes
protected[this]
Definition Classes
StrictOptimizedIterableOps
Annotations
@inline()
final def strictOptimizedFlatMap[B, C2](b: Builder[B, C2], f: (A) => IterableOnce[B]): C2
B
Type of elements of the resulting collection (e.g. String)
C2
Type of the resulting collection (e.g. List[String])
b
Builder to use to build the resulting collection
f
Element transformation function
returns
The resulting collection
Attributes
protected[this]
Definition Classes
StrictOptimizedIterableOps
Annotations
@inline()
final def strictOptimizedFlatten[B, C2](b: Builder[B, C2])(implicit toIterableOnce: (A) => IterableOnce[B]): C2
B
Type of elements of the resulting collection (e.g. Int)
C2
Type of the resulting collection (e.g. List[Int])
b
Builder to use to build the resulting collection
toIterableOnce
Evidence that A can be seen as an IterableOnce[B]
returns
The resulting collection
Attributes
protected[this]
Definition Classes
StrictOptimizedIterableOps
Annotations
@inline()
final def strictOptimizedMap[B, C2](b: Builder[B, C2], f: (A) => B): C2
B
Type of elements of the resulting collection (e.g. String)
C2
Type of the resulting collection (e.g. List[String])
b
Builder to use to build the resulting collection
f
Element transformation function
returns
The resulting collection
Attributes
protected[this]
Definition Classes
StrictOptimizedIterableOps
Annotations
@inline()
final def strictOptimizedZip[B, C2](that: IterableOnce[B], b: Builder[(A, B), C2]): C2
B
Type of elements of the second collection (e.g. String)
C2
Type of the resulting collection (e.g. List[(Int, String)])
that
Collection to zip with this collection
b
Builder to use to build the resulting collection
returns
The resulting collection
Attributes
protected[this]
Definition Classes
StrictOptimizedIterableOps
Annotations
@inline()
def stringPrefix: String
Attributes
protected[this]
Definition Classes
LinearSeq → Seq → Iterable
Annotations
@nowarn()
def sum[B >: A](implicit num: math.Numeric[B]): B
Sums up the elements of this collection.
Sums up the elements of this collection.
B
the result type of the + operator.
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 list with respect to the + operator in num.
Definition Classes
IterableOnceOps
final def synchronized[T0](arg0: => T0): T0
Executes the code in body with an exclusive lock on this.
Executes the code in body with an exclusive lock on this.
returns
the result of body
Definition Classes
AnyRef
def tail: List[A]
The rest of the collection without its first element.
The rest of the collection without its first element.
Definition Classes
IterableOps
def tails: Iterator[List[A]]
Iterates over the tails of this list.
Iterates over the tails of this list. The first value will be this list and the final one will be an empty list, with the intervening values the results of successive applications of tail.
returns
an iterator over all the tails of this list
Definition Classes
LinearSeqOps → IterableOps
Example:
1. List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)
def take(n: Int): List[A]
Selects the first n elements.
Selects the 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
List → IterableOps → IterableOnceOps
def takeRight(n: Int): List[A]
A collection containing the last n elements of this collection.
A collection containing the last n elements of this collection.
Note: Even when applied to a view or a lazy collection it will always force the elements.
n
the number of elements to take from this list.
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. If n is negative, returns an empty list.
Definition Classes
List → StrictOptimizedIterableOps → IterableOps
final def takeWhile(p: (A) => Boolean): List[A]
Takes longest prefix of elements that satisfy a predicate.
Takes longest prefix of elements that satisfy a predicate.
p
The predicate used to test elements.
returns
the longest prefix of this list whose elements all satisfy the predicate p.
Definition Classes
List → IterableOps → IterableOnceOps
Annotations
@inline()
def tapEach[U](f: (A) => U): List[A]
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.
U
the return type of f
f
a function to apply to each element in this list
returns
The same logical collection as this
Definition Classes
StrictOptimizedIterableOps → IterableOps → IterableOnceOps
def to[C1](factory: Factory[A, C1]): C1
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]
Definition Classes
IterableOnceOps
def toArray[B >: A](implicit arg0: ClassTag[B]): Array[B]
Convert collection to array.
Convert collection to array.
Implementation note: DO NOT call Array.from from this method.
Definition Classes
IterableOnceOps
final def toBuffer[B >: A]: Buffer[B]
Definition Classes
IterableOnceOps
Annotations
@inline()
def toIndexedSeq: IndexedSeq[A]
Definition Classes
IterableOnceOps
final def toList: List[A]
Definition Classes
List → IterableOnceOps
def toMap[K, V](implicit ev: <:<[A, (K, V)]): Map[K, V]
Definition Classes
IterableOnceOps
final def toSeq: List.this.type
returns
This collection as a Seq[A]. This is equivalent to to(Seq) but might be faster.
Definition Classes
Seq → IterableOnceOps
def toSet[B >: A]: Set[B]
Definition Classes
IterableOnceOps
def toString(): String
Creates a String representation of this object.
Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.
returns
a String representation of the object.
Definition Classes
Seq → Function1 → Iterable → AnyRef → Any
def toVector: Vector[A]
Definition Classes
IterableOnceOps
def transpose[B](implicit asIterable: (A) => collection.Iterable[B]): List[List[B]]
Transposes this list of iterable collections into a list of lists.
Transposes this list of iterable collections into a list of lists.
The resulting collection's type will be guided by the static type of list. 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))
```
Note: Even when applied to a view or a lazy collection it will always force the elements.
B
the type of the elements of each iterable collection.
asIterable
an implicit conversion which asserts that the element type of this list is an Iterable.
returns
a two-dimensional list of lists which has as nth row the nth column of this list.
Definition Classes
IterableOps
Exceptions thrown
IllegalArgumentException if all collections in this list are not of the same size.
def unapply(a: Int): Option[A]
Tries to extract a B from an A in a pattern matching expression.
Tries to extract a B from an A in a pattern matching expression.
Definition Classes
PartialFunction
def unlift: PartialFunction[Int, B]
Converts an optional function to a partial function.
Converts an optional function to a partial function.
Implicit
This member is added by an implicit conversion from List[A] toUnliftOps[Int, B] performed by method UnliftOps in scala.Function1.This conversion will take place only if A is a subclass of Option[B] (A <: Option[B]).
Definition Classes
UnliftOps
Example:
1. Unlike Function.unlift, this UnliftOps.unlift method can be used in extractors.
  val of: Int => Option[String] = { i => if (i == 2) { Some("matched by an optional function") } else { None } } util.Random.nextInt(4) match { case of.unlift(m) => // Convert an optional function to a pattern println(m) case _ => println("Not matched") }
def unzip[A1, A2](implicit asPair: (A) => (A1, A2)): (List[A1], List[A2])
Converts this list of pairs into two collections of the first and second half of each pair.
Converts this list of pairs into two collections of the first and second half of each pair.
```
val xs = `List`(
           (1, "one"),
           (2, "two"),
           (3, "three")).unzip
// xs == (`List`(1, 2, 3),
//        `List`(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 list is a pair.
returns
a pair of lists, containing the first, respectively second half of each element pair of this list.
Definition Classes
StrictOptimizedIterableOps → IterableOps
def unzip3[A1, A2, A3](implicit asTriple: (A) => (A1, A2, A3)): (List[A1], List[A2], List[A3])
Converts this list of triples into three collections of the first, second, and third element of each triple.
Converts this list of triples into three collections of the first, second, and third element of each triple.
```
val xs = `List`(
           (1, "one", '1'),
           (2, "two", '2'),
           (3, "three", '3')).unzip3
// xs == (`List`(1, 2, 3),
//        `List`(one, two, three),
//        `List`(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 list is a triple.
returns
a triple of lists, containing the first, second, respectively third member of each element triple of this list.
Definition Classes
StrictOptimizedIterableOps → IterableOps
def updated[B >: A](index: Int, elem: B): List[B]
A copy of this list with one single replaced element.
A copy of this list with one single replaced element.
B
the element type of the returned list.
index
the position of the replacement
elem
the replacing element
returns
a new list which is a copy of this list with the element at position index replaced by elem.
Definition Classes
List → StrictOptimizedSeqOps → SeqOps
Exceptions thrown
IndexOutOfBoundsException if index does not satisfy 0 <= index < length. In case of a lazy collection this exception may be thrown at a later time or not at all (if the end of the collection is never evaluated).
def view: SeqView[A]
A view over the elements of this collection.
A view over the elements of this collection.
Definition Classes
SeqOps → IterableOps
final def wait(): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
Note
not specified by SLS as a member of AnyRef
final def wait(arg0: Long, arg1: Int): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
Note
not specified by SLS as a member of AnyRef
final def wait(arg0: Long): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException]) @native()
Note
not specified by SLS as a member of AnyRef
def withFilter(p: (A) => Boolean): WithFilter[A, [_]List[_]]
Creates a non-strict filter of this list.
Creates a non-strict filter of this list.
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.
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 list which satisfy the predicate p.
Definition Classes
IterableOps
def writeReplace(): AnyRef
Attributes
protected[this]
Definition Classes
DefaultSerializable
def zip[B](that: IterableOnce[B]): List[(A, B)]
Returns a list formed from this list and another iterable collection by combining corresponding elements in pairs.
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
StrictOptimizedIterableOps → IterableOps
def zipAll[A1 >: A, B](that: collection.Iterable[B], thisElem: A1, thatElem: B): List[(A1, B)]
Returns a list formed from this list and another iterable collection by combining corresponding elements in pairs.
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.
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 collection of type That 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
IterableOps
def zipWithIndex: List[(A, Int)]
Zips this list with its indices.
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
StrictOptimizedIterableOps → IterableOps → IterableOnceOps
Example:
1. List("a", "b", "c").zipWithIndex == List(("a", 0), ("b", 1), ("c", 2))

Deprecated Value Members

def /:[B](z: B)(op: (B, A) => B): B
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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:
(list: IterableOnceExtensionMethods[A])./:(z)(op)
Definition Classes
IterableOnceExtensionMethods
Annotations
@deprecated @inline()
Deprecated
(Since version 2.13.0) Use .iterator.foldLeft instead
final def /:[B](z: B)(op: (B, A) => B): B
Definition Classes
IterableOnceOps
Annotations
@deprecated @inline()
Deprecated
(Since version 2.13.0) Use foldLeft instead of /:
def :\[B](z: B)(op: (A, B) => B): B
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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:
(list: IterableOnceExtensionMethods[A]).:\(z)(op)
Definition Classes
IterableOnceExtensionMethods
Annotations
@deprecated @inline()
Deprecated
(Since version 2.13.0) Use .iterator.foldRight instead
final def :\[B](z: B)(op: (A, B) => B): B
Definition Classes
IterableOnceOps
Annotations
@deprecated @inline()
Deprecated
(Since version 2.13.0) Use foldRight instead of :\
def aggregate[B](z: => B)(seqop: (B, A) => B, combop: (B, B) => B): B
Definition Classes
IterableOnceOps
Annotations
@deprecated
Deprecated
(Since version 2.13.0) aggregate is not relevant for sequential collections. Use foldLeft(z)(seqop) instead.
def collectFirst[B](f: PartialFunction[A, B]): Option[B]
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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:
(list: IterableOnceExtensionMethods[A]).collectFirst(f)
Definition Classes
IterableOnceExtensionMethods
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.collectFirst(...) instead
def companion: IterableFactory[[_]List[_]]
Definition Classes
IterableOps
Annotations
@deprecated @deprecatedOverriding() @inline()
Deprecated
(Since version 2.13.0) Use iterableFactory instead
def copyToBuffer(dest: Buffer[A]): Unit
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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:
(list: IterableOnceExtensionMethods[A]).copyToBuffer(dest)
Definition Classes
IterableOnceExtensionMethods
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.copyToBuffer(...) instead
final def copyToBuffer[B >: A](dest: Buffer[B]): Unit
Definition Classes
IterableOnceOps
Annotations
@deprecated @inline()
Deprecated
(Since version 2.13.0) Use dest ++= coll instead
def count(f: (A) => Boolean): Int
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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:
(list: IterableOnceExtensionMethods[A]).count(f)
Definition Classes
IterableOnceExtensionMethods
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.count(...) instead
def exists(f: (A) => Boolean): Boolean
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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:
(list: IterableOnceExtensionMethods[A]).exists(f)
Definition Classes
IterableOnceExtensionMethods
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.exists(...) instead
def filter(f: (A) => Boolean): Iterator[A]
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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:
(list: IterableOnceExtensionMethods[A]).filter(f)
Definition Classes
IterableOnceExtensionMethods
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.filter(...) instead
def find(p: (A) => Boolean): Option[A]
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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:
(list: IterableOnceExtensionMethods[A]).find(p)
Definition Classes
IterableOnceExtensionMethods
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.find instead
def flatMap[B](f: (A) => IterableOnce[B]): IterableOnce[B]
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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:
(list: IterableOnceExtensionMethods[A]).flatMap(f)
Definition Classes
IterableOnceExtensionMethods
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.flatMap instead or consider requiring an Iterable
def fold[A1 >: A](z: A1)(op: (A1, A1) => A1): A1
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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:
(list: IterableOnceExtensionMethods[A]).fold(z)(op)
Definition Classes
IterableOnceExtensionMethods
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.fold instead
def foldLeft[B](z: B)(op: (B, A) => B): B
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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:
(list: IterableOnceExtensionMethods[A]).foldLeft(z)(op)
Definition Classes
IterableOnceExtensionMethods
Annotations
@deprecated @inline()
Deprecated
(Since version 2.13.0) Use .iterator.foldLeft instead
def foldRight[B](z: B)(op: (A, B) => B): B
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
Shadowing
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To access this member you can use a type ascription:
(list: IterableOnceExtensionMethods[A]).foldRight(z)(op)
Definition Classes
IterableOnceExtensionMethods
Annotations
@deprecated @inline()
Deprecated
(Since version 2.13.0) Use .iterator.foldRight instead
def forall(f: (A) => Boolean): Boolean
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
Shadowing
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Definition Classes
IterableOnceExtensionMethods
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.forall(...) instead
def foreach[U](f: (A) => U): Unit
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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@deprecated @inline()
Deprecated
(Since version 2.13.0) Use .iterator.foreach(...) instead
def formatted(fmtstr: String): String
Returns string formatted according to given format 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 List[A] toStringFormat[List[A]] performed by method StringFormat in scala.Predef.
Definition Classes
StringFormat
Annotations
@deprecated @inline()
Deprecated
(Since version 2.12.16) Use formatString.format(value) instead of value.formatted(formatString), or use the f"" string interpolator. In Java 15 and later, formatted resolves to the new method in String which has reversed parameters.
def hasDefiniteSize: Boolean
Tests whether this list is known to have a finite size.
Tests whether this list 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
IterableOnceOps
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Check .knownSize instead of .hasDefiniteSize for more actionable information (see scaladoc for details)
See also
method knownSize for a more useful alternative
def isEmpty: Boolean
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.isEmpty instead
def map[B](f: (A) => B): IterableOnce[B]
Implicit
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@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.map instead or consider requiring an Iterable
def max(implicit ord: math.Ordering[A]): A
Implicit
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(Since version 2.13.0) Use .iterator.max instead
def maxBy[B](f: (A) => B)(implicit cmp: math.Ordering[B]): A
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@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.maxBy(...) instead
def min(implicit ord: math.Ordering[A]): A
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Deprecated
(Since version 2.13.0) Use .iterator.min instead
def minBy[B](f: (A) => B)(implicit cmp: math.Ordering[B]): A
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(Since version 2.13.0) Use .iterator.minBy(...) instead
def mkString: String
Implicit
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(Since version 2.13.0) Use .iterator.mkString instead
def mkString(sep: String): String
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(Since version 2.13.0) Use .iterator.mkString instead
def mkString(start: String, sep: String, end: String): String
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Deprecated
(Since version 2.13.0) Use .iterator.mkString instead
def nonEmpty: Boolean
Implicit
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Deprecated
(Since version 2.13.0) Use .iterator.nonEmpty instead
final def prefixLength(p: (A) => Boolean): Int
Returns the length of the longest prefix whose elements all satisfy some predicate.
Returns the length of the longest prefix whose elements all satisfy some predicate.
p
the predicate used to test elements.
returns
the length of the longest prefix of this list such that every element of the segment satisfies the predicate p.
Definition Classes
SeqOps
Annotations
@deprecated @inline()
Deprecated
(Since version 2.13.0) Use segmentLength instead of prefixLength
def product(implicit num: math.Numeric[A]): A
Implicit
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(Since version 2.13.0) Use .iterator.product instead
def reduce(f: (A, A) => A): A
Implicit
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(Since version 2.13.0) Use .iterator.reduce(...) instead
def reduceLeft(f: (A, A) => A): A
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(Since version 2.13.0) Use .iterator.reduceLeft(...) instead
def reduceLeftOption(f: (A, A) => A): Option[A]
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@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.reduceLeftOption(...) instead
def reduceOption(f: (A, A) => A): Option[A]
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@deprecated
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(Since version 2.13.0) Use .iterator.reduceOption(...) instead
def reduceRight(f: (A, A) => A): A
Implicit
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@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.reduceRight(...) instead
def reduceRightOption(f: (A, A) => A): Option[A]
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.reduceRightOption(...) instead
final def repr: List[A]
Definition Classes
IterableOps
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use coll instead of repr in a collection implementation, use the collection value itself from the outside
def reverseMap[B](f: (A) => B): List[B]
Definition Classes
SeqOps
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use .reverseIterator.map(f).to(...) instead of .reverseMap(f)
def sameElements[B >: A](that: IterableOnce[B]): Boolean
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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Definition Classes
IterableOnceExtensionMethods
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.sameElements instead
def seq: List.this.type
Definition Classes
Iterable
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Iterable.seq always returns the iterable itself
def size: Int
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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Deprecated
(Since version 2.13.0) Use .iterator.size instead
def sum(implicit num: math.Numeric[A]): A
Implicit
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Deprecated
(Since version 2.13.0) Use .iterator.sum instead
def to[C1](factory: Factory[A, C1]): C1
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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(Since version 2.13.0) Use .iterator.to(factory) instead
def toArray[B >: A](implicit arg0: ClassTag[B]): Array[B]
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.toArray
def toBuffer[B >: A]: Buffer[B]
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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Deprecated
(Since version 2.13.0) Use .iterator.to(ArrayBuffer) instead
def toIndexedSeq: collection.IndexedSeq[A]
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.toIndexedSeq instead
final def toIterable: collection.Iterable[A]
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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@deprecated @inline()
Deprecated
(Since version 2.13.0) Use .iterator.to(Iterable) instead
final def toIterable: List.this.type
returns
This collection as an Iterable[A]. No new collection will be built if this is already an Iterable[A].
Definition Classes
Iterable → IterableOps
Annotations
@deprecated
Deprecated
(Since version 2.13.7) toIterable is internal and will be made protected; its name is similar to toList or toSeq, but it doesn't copy non-immutable collections
def toIterator: Iterator[A]
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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@deprecated @inline()
Deprecated
(Since version 2.13.0) Use .iterator instead
final def toIterator: Iterator[A]
Definition Classes
IterableOnceOps
Annotations
@deprecated @inline()
Deprecated
(Since version 2.13.0) Use .iterator instead of .toIterator
def toList: List[A]
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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Deprecated
(Since version 2.13.0) Use .iterator.to(List) instead
def toMap[K, V](implicit ev: <:<[A, (K, V)]): Map[K, V]
Implicit
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Deprecated
(Since version 2.13.0) Use .iterator.to(Map) instead
def toSeq: Seq[A]
Implicit
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Deprecated
(Since version 2.13.0) Use .iterator.to(Seq) instead
def toSet[B >: A]: Set[B]
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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Deprecated
(Since version 2.13.0) Use .iterator.to(Set) instead
def toStream: Stream[A]
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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Annotations
@deprecated @inline()
Deprecated
(Since version 2.13.0) Use .iterator.to(LazyList) instead
final def toStream: Stream[A]
Definition Classes
IterableOnceOps
Annotations
@deprecated @inline()
Deprecated
(Since version 2.13.0) Use .to(LazyList) instead of .toStream
final def toTraversable: collection.Traversable[A]
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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@deprecated @inline()
Deprecated
(Since version 2.13.0) Use .iterator.to(Iterable) instead
final def toTraversable: collection.Traversable[A]
Converts this list to an unspecified Iterable.
Converts this list to an unspecified Iterable. Will return the same collection if this instance is already Iterable.
returns
An Iterable containing all elements of this list.
Definition Classes
IterableOps
Annotations
@deprecated
Deprecated
(Since version 2.13.0) toTraversable is internal and will be made protected; its name is similar to toList or toSeq, but it doesn't copy non-immutable collections
def toVector: Vector[A]
Implicit
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@deprecated @inline()
Deprecated
(Since version 2.13.0) Use .iterator.to(Vector) instead
final def union[B >: A](that: collection.Seq[B]): List[B]
Produces a new sequence which contains all elements of this list and also all elements of a given sequence.
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.
B
the element type of the returned list.
that
the sequence to add.
returns
a new collection which contains all elements of this list followed by all elements of that.
Definition Classes
SeqOps
Annotations
@deprecated @inline()
Deprecated
(Since version 2.13.0) Use concat instead
def view(from: Int, until: Int): View[A]
A view over a slice of the elements of this collection.
A view over a slice of the elements of this collection.
Definition Classes
IterableOps
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use .view.slice(from, until) instead of .view(from, until)
def withFilter(f: (A) => Boolean): Iterator[A]
Implicit
This member is added by an implicit conversion from List[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
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Definition Classes
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Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.withFilter(...) instead
def →[B](y: B): (List[A], B)
Implicit
This member is added by an implicit conversion from List[A] toArrowAssoc[List[A]] performed by method ArrowAssoc in scala.Predef.This conversion will take place only if A is a subclass of Option[Nothing] (A <: Option[Nothing]).
Definition Classes
ArrowAssoc
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use -> instead. If you still wish to display it as one character, consider using a font with programming ligatures such as Fira Code.

Inherited from DefaultSerializable

Inherited from java.io.Serializable

Inherited from StrictOptimizedSeqOps[A, List, List[A]]

Packages

Package structure

Automatic imports

List

Companion object List

sealed abstract class List[+A] extends AbstractSeq[A] with LinearSeq[A] with LinearSeqOps[A, List, List[A]] with StrictOptimizedLinearSeqOps[A, List, List[A]] with StrictOptimizedSeqOps[A, List, List[A]] with IterableFactoryDefaults[A, List] with DefaultSerializable

Performance

Value Members

Deprecated Value Members

Inherited from DefaultSerializable

Inherited from java.io.Serializable

Inherited from StrictOptimizedSeqOps[A, List, List[A]]

Inherited from StrictOptimizedLinearSeqOps[A, List, List[A]]

Inherited from collection.StrictOptimizedSeqOps[A, List, List[A]]

Inherited from StrictOptimizedIterableOps[A, List, List[A]]

Inherited from LinearSeq[A]

Inherited from LinearSeqOps[A, [X]List[X], List[A]]

Inherited from collection.LinearSeq[A]

Inherited from collection.LinearSeqOps[A, [X]List[X], List[A]]

Inherited from AbstractSeq[A]

Inherited from Seq[A]

Inherited from SeqOps[A, [_]List[_], List[A]]

Inherited from Iterable[A]

Inherited from collection.AbstractSeq[A]

Inherited from collection.Seq[A]

Inherited from Equals

Inherited from collection.SeqOps[A, [_]List[_], List[A]]

Inherited from PartialFunction[Int, A]

Inherited from (Int) => A

Inherited from AbstractIterable[A]

Inherited from collection.Iterable[A]

Inherited from IterableFactoryDefaults[A, [x]List[x]]

Inherited from IterableOps[A, [_]List[_], List[A]]

Inherited from IterableOnceOps[A, [_]List[_], List[A]]

Inherited from IterableOnce[A]

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion UnliftOps fromList[A] to UnliftOps[Int, B]

Inherited by implicit conversion iterableOnceExtensionMethods fromList[A] to IterableOnceExtensionMethods[A]

Inherited by implicit conversion any2stringadd fromList[A] to any2stringadd[List[A]]

Inherited by implicit conversion StringFormat fromList[A] to StringFormat[List[A]]

Inherited by implicit conversion Ensuring fromList[A] to Ensuring[List[A]]

Inherited by implicit conversion ArrowAssoc fromList[A] to ArrowAssoc[List[A]]

Ungrouped

List