trait IterableOps[+A, +CC[_], +C] extends IterableOnce[A] with IterableOnceOps[A, CC, C]
Base trait for Iterable operations
VarianceNote
We require that for all child classes of Iterable the variance of
the child class and the variance of the C
parameter passed to IterableOps
are the same. We cannot express this since we lack variance polymorphism. That's
why we have to resort at some places to write C[A @uncheckedVariance]
.
- CC
type constructor of the collection (e.g.
List
,Set
). Operations returning a collection with a different type of elementB
(e.g.map
) return aCC[B]
.- C
type of the collection (e.g.
List[Int]
,String
,BitSet
). Operations returning a collection with the same type of element (e.g.drop
,filter
) return aC
.
- Source
- Iterable.scala
- Alphabetic
- By Inheritance
- IterableOps
- IterableOnceOps
- IterableOnce
- Any
- by iterableOnceExtensionMethods
- by any2stringadd
- by StringFormat
- by Ensuring
- by ArrowAssoc
- Hide All
- Show All
- Public
- Protected
Abstract Value Members
- abstract def coll: C
- returns
This collection as a
C
.
- Attributes
- protected
- abstract def fromSpecific(coll: IterableOnce[A]): C
Defines how to turn a given
Iterable[A]
into a collection of typeC
.Defines how to turn a given
Iterable[A]
into a collection of typeC
.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
- 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 whereC =:= 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 anIterable[A]
obtained fromthis
collection (as it is the case in the implementations of operations where we use aView[A]
), it is safe.
- abstract 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
- Any
- abstract def iterableFactory: IterableFactory[CC]
The companion object of this iterable collection, providing various factory methods.
The companion object of this iterable collection, providing various factory methods.
- 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).
- abstract def iterator: Iterator[A]
An scala.collection.Iterator over the elements of this iterable collection.
An scala.collection.Iterator over the elements of this iterable collection.
If an
IterableOnce
object is in fact an scala.collection.Iterator, this method always returns itself, in its current state, but if it is an scala.collection.Iterable, this method always returns a new scala.collection.Iterator.- Definition Classes
- IterableOnce
- abstract def newSpecificBuilder: Builder[A, C]
- 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 withfromSpecific
instead of this method.
- Attributes
- protected
- 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 whereC =:= 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 withA
values taken fromthis
instance, it is safe.
- abstract def toIterable: Iterable[A]
- returns
This collection as an
Iterable[A]
. No new collection will be built ifthis
is already anIterable[A]
.
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.7) toIterable is internal and will be made protected; its name is similar to
toList
ortoSeq
, but it doesn't copy non-immutable collections
Concrete 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
- Any
- final def ##: Int
Equivalent to
x.hashCode
except for boxed numeric types andnull
.Equivalent to
x.hashCode
except for boxed numeric types andnull
. 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. Fornull
returns a hashcode wherenull.hashCode
throws aNullPointerException
.- returns
a hash value consistent with ==
- Definition Classes
- Any
- def +(other: String): String
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] toany2stringadd[IterableOps[A, CC, C]] performed by method any2stringadd in scala.Predef.
- Definition Classes
- any2stringadd
- final def ++[B >: A](suffix: IterableOnce[B]): CC[B]
Alias for
concat
Alias for
concat
- Annotations
- @inline()
- def ->[B](y: B): (IterableOps[A, CC, C], B)
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] toArrowAssoc[IterableOps[A, CC, C]] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
- Annotations
- @inline()
- final def ==(arg0: Any): Boolean
Test two objects for equality.
Test two objects for equality. The expression
x == that
is equivalent toif (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
- Any
- final def addString(b: mutable.StringBuilder): b.type
Appends all elements of this iterable collection to a string builder.
Appends all elements of this iterable collection to a string builder. The written text consists of the string representations (w.r.t. the method
toString
) of all elements of this iterable collection without any separator string.Example:
scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = new StringBuilder() b: StringBuilder = scala> val h = a.addString(b) h: StringBuilder = 1234
- 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 iterable collection to a string builder using a separator string.
Appends all elements of this iterable collection to a string builder using a separator string. The written text consists of the string representations (w.r.t. the method
toString
) of all elements of this iterable collection, separated by the stringsep
.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 iterable collection to a string builder using start, end, and separator strings.
Appends all elements of this iterable collection to a string builder using start, end, and separator strings. The written text begins with the string
start
and ends with the stringend
. Inside, the string representations (w.r.t. the methodtoString
) of all elements of this iterable collection are separated by the stringsep
.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
- final def asInstanceOf[T0]: T0
Forces the compiler to treat the receiver object as having type
T0
, even though doing so may violate type safety.Forces the compiler to treat the receiver object as having type
T0
, even though doing so may violate type safety.This method is useful when you believe you have type information the compiler doesn't, and it also isn't possible to check the type at runtime. In such situations, skipping type safety is the only option.
It is platform dependent whether
asInstanceOf
has any effect at runtime. It might do a runtime type test on the erasure ofT0
, insert a conversion (such as boxing/unboxing), fill in a default value, or do nothing at all.In particular,
asInstanceOf
is not a type test. It does **not** mean:this match { case x: T0 => x case _ => throw ClassCastException("...")
Use pattern matching or isInstanceOf for type testing instead.
Situations where
asInstanceOf
is useful:- when flow analysis fails to deduce
T0
automatically - when down-casting a type parameter or an abstract type member (which cannot be checked at runtime due to type erasure) If there is any doubt and you are able to type test instead, you should do so.
Be careful of using
asInstanceOf
whenT0
is a primitive type. WhenT0
is primitive,asInstanceOf
may insert a conversion instead of a type test. If your intent is to convert, use atoT
method (x.toChar
,x.toByte
, etc.).- returns
the receiver object.
- Definition Classes
- Any
- Exceptions thrown
ClassCastException
if the receiver is not an instance of the erasure ofT0
, if that can be checked on this platform
- when flow analysis fails to deduce
- def collect[B](pf: PartialFunction[A, B]): CC[B]
Builds a new iterable collection by applying a partial function to all elements of this iterable collection on which the function is defined.
Builds a new iterable collection by applying a partial function to all elements of this iterable collection on which the function is defined.
- B
the element type of the returned iterable collection.
- pf
the partial function which filters and maps the iterable collection.
- returns
a new iterable collection resulting from applying the given partial function
pf
to each element on which it is defined and collecting the results. The order of the elements is preserved.
- Definition Classes
- IterableOps → IterableOnceOps
- def collectFirst[B](pf: PartialFunction[A, B]): Option[B]
Finds the first element of the iterable collection for which the given partial function is defined, and applies the partial function to it.
Finds the first element of the iterable collection for which the given partial function is defined, and applies the partial function to it.
Note: may not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- 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
Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)
Example: - def concat[B >: A](suffix: IterableOnce[B]): CC[B]
Returns a new iterable collection containing the elements from the left hand operand followed by the elements from the right hand operand.
Returns a new iterable collection containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the iterable collection 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 iterable collection which contains all elements of this iterable collection followed by all elements of
suffix
.
- 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 indexstart
with at mostlen
elements of this iterable collection.Copying will stop once either all the elements of this iterable collection 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
Copies elements to an array, returning the number of elements written.
Copies elements to an array, returning the number of elements written.
Fills the given array
xs
starting at indexstart
with values of this iterable collection.Copying will stop once either all the elements of this iterable collection 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
Copies elements to an array, returning the number of elements written.
Copies elements to an array, returning the number of elements written.
Fills the given array
xs
starting at indexstart
with values of this iterable collection.Copying will stop once either all the elements of this iterable collection 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: 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.
Note: will not terminate for infinite-sized collections.
- 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 andp(x, y)
istrue
for all corresponding elementsx
of this iterator andy
ofthat
, otherwisefalse
- Definition Classes
- IterableOnceOps
- def count(p: (A) => Boolean): Int
Counts the number of elements in the iterable collection which satisfy a predicate.
Counts the number of elements in the iterable collection which satisfy a predicate.
Note: will not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
the number of elements satisfying the predicate
p
.
- Definition Classes
- IterableOnceOps
- def drop(n: Int): C
Selects all elements except the first
n
ones.Selects all elements except the first
n
ones.Note: might return different results for different runs, unless the underlying collection type is ordered.
- n
the number of elements to drop from this iterable collection.
- returns
a iterable collection consisting of all elements of this iterable collection except the first
n
ones, or else the empty iterable collection, if this iterable collection has less thann
elements. Ifn
is negative, don't drop any elements.
- Definition Classes
- IterableOps → IterableOnceOps
- def dropRight(n: Int): C
Selects all elements except last n ones.
Selects all elements except last n ones.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- n
the number of elements to drop from this iterable collection.
- returns
a iterable collection consisting of all elements of this iterable collection except the last
n
ones, or else the empty iterable collection, if this iterable collection has less thann
elements. Ifn
is negative, don't drop any elements.
- def dropWhile(p: (A) => Boolean): C
Selects all elements except the longest prefix that satisfies a predicate.
Selects all elements except the longest prefix that satisfies a predicate.
The matching prefix starts with the first element of this iterable collection, and the element following the prefix is the first element that does not satisfy the predicate. The matching prefix may be empty, so that this method returns the entire iterable collection.
Example:
scala> List(1, 2, 3, 100, 4).dropWhile(n => n < 10) val res0: List[Int] = List(100, 4) scala> List(1, 2, 3, 100, 4).dropWhile(n => n == 0) val res1: List[Int] = List(1, 2, 3, 100, 4)
Use span to obtain both the prefix and suffix. Use filterNot to drop all elements that satisfy the predicate.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- p
The predicate used to test elements.
- returns
the longest suffix of this iterable collection whose first element does not satisfy the predicate
p
.
- Definition Classes
- IterableOps → IterableOnceOps
- def empty: C
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
.
- def ensuring(cond: (IterableOps[A, CC, C]) => Boolean, msg: => Any): IterableOps[A, CC, C]
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] toEnsuring[IterableOps[A, CC, C]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: (IterableOps[A, CC, C]) => Boolean): IterableOps[A, CC, C]
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] toEnsuring[IterableOps[A, CC, C]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: Boolean, msg: => Any): IterableOps[A, CC, C]
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] toEnsuring[IterableOps[A, CC, C]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: Boolean): IterableOps[A, CC, C]
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] toEnsuring[IterableOps[A, CC, C]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def equals(arg0: Any): Boolean
Compares the receiver object (
this
) with the argument object (that
) for equivalence.Compares the receiver object (
this
) with the argument object (that
) for equivalence.Any implementation of this method should be an equivalence relation:
- It is reflexive: for any instance
x
of typeAny
,x.equals(x)
should returntrue
. - It is symmetric: for any instances
x
andy
of typeAny
,x.equals(y)
should returntrue
if and only ify.equals(x)
returnstrue
. - It is transitive: for any instances
x
,y
, andz
of typeAny
ifx.equals(y)
returnstrue
andy.equals(z)
returnstrue
, thenx.equals(z)
should returntrue
.
If you override this method, you should verify that your implementation remains an equivalence relation. Additionally, when overriding this method it is usually necessary to override
hashCode
to ensure that objects which are "equal" (o1.equals(o2)
returnstrue
) hash to the same scala.Int. (o1.hashCode.equals(o2.hashCode)
).- returns
true
if the receiver object is equivalent to the argument;false
otherwise.
- Definition Classes
- Any
- It is reflexive: for any instance
- def exists(p: (A) => Boolean): Boolean
Tests whether a predicate holds for at least one element of this iterable collection.
Tests whether a predicate holds for at least one element of this iterable collection.
Note: may not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
true
if the given predicatep
is satisfied by at least one element of this iterable collection, otherwisefalse
- Definition Classes
- IterableOnceOps
- def filter(pred: (A) => Boolean): C
Selects all elements of this iterable collection which satisfy a predicate.
Selects all elements of this iterable collection which satisfy a predicate.
- returns
a new iterable collection consisting of all elements of this iterable collection that satisfy the given predicate
p
. The order of the elements is preserved.
- Definition Classes
- IterableOps → IterableOnceOps
- def filterNot(pred: (A) => Boolean): C
Selects all elements of this iterable collection which do not satisfy a predicate.
Selects all elements of this iterable collection which do not satisfy a predicate.
- pred
the predicate used to test elements.
- returns
a new iterable collection consisting of all elements of this iterable collection that do not satisfy the given predicate
pred
. Their order may not be preserved.
- Definition Classes
- IterableOps → IterableOnceOps
- def find(p: (A) => Boolean): Option[A]
Finds the first element of the iterable collection satisfying a predicate, if any.
Finds the first element of the iterable collection satisfying a predicate, if any.
Note: may not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- p
the predicate used to test elements.
- returns
an option value containing the first element in the iterable collection that satisfies
p
, orNone
if none exists.
- Definition Classes
- IterableOnceOps
- def flatMap[B](f: (A) => IterableOnce[B]): CC[B]
Builds a new iterable collection by applying a function to all elements of this iterable collection and using the elements of the resulting collections.
Builds a new iterable collection by applying a function to all elements of this iterable collection and using the elements of the resulting collections.
For example:
def getWords(lines: Seq[String]): Seq[String] = lines flatMap (line => line split "\\W+")
The type of the resulting collection is guided by the static type of iterable collection. This might cause unexpected results sometimes. For example:
// lettersOf will return a Seq[Char] of likely repeated letters, instead of a Set def lettersOf(words: Seq[String]) = words flatMap (word => word.toSet) // lettersOf will return a Set[Char], not a Seq def lettersOf(words: Seq[String]) = words.toSet flatMap ((word: String) => word.toSeq) // xs will be an Iterable[Int] val xs = Map("a" -> List(11,111), "b" -> List(22,222)).flatMap(_._2) // ys will be a Map[Int, Int] val ys = Map("a" -> List(1 -> 11,1 -> 111), "b" -> List(2 -> 22,2 -> 222)).flatMap(_._2)
- B
the element type of the returned collection.
- f
the function to apply to each element.
- returns
a new iterable collection resulting from applying the given collection-valued function
f
to each element of this iterable collection and concatenating the results.
- Definition Classes
- IterableOps → IterableOnceOps
- def flatten[B](implicit asIterable: (A) => IterableOnce[B]): CC[B]
Converts this iterable collection of iterable collections into a iterable collection formed by the elements of these iterable collections.
Converts this iterable collection of iterable collections into a iterable collection formed by the elements of these iterable collections.
The resulting collection's type will be guided by the type of iterable collection. For example:
val xs = List( Set(1, 2, 3), Set(1, 2, 3) ).flatten // xs == List(1, 2, 3, 1, 2, 3) val ys = Set( List(1, 2, 3), List(3, 2, 1) ).flatten // ys == Set(1, 2, 3)
- B
the type of the elements of each iterable collection.
- asIterable
an implicit conversion which asserts that the element type of this iterable collection is an
Iterable
.- returns
a new iterable collection resulting from concatenating all element iterable collections.
- Definition Classes
- IterableOps → IterableOnceOps
- def fold[A1 >: A](z: A1)(op: (A1, A1) => A1): A1
Applies the given binary operator
op
to the given initial valuez
and all elements of this iterable collection.Applies the given binary operator
op
to the given initial valuez
and all elements of this iterable collection.For each application of the operator, each operand is either an element of this iterable collection, the initial value, or another such application of the operator.
The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation. The initial value may be used an arbitrary number of times, but at least once.
If this collection is ordered, then for any application of the operator, the element(s) appearing in the left operand will precede those in the right.
Note: might return different results for different runs, unless either of the following conditions is met: (1) the operator is associative, and the underlying collection type is ordered; or (2) the operator is associative and commutative. In either case, it is also necessary that the initial value be a neutral value for the operator, e.g.
Nil
forList
concatenation or1
for multiplication.The default implementation in
IterableOnce
is equivalent tofoldLeft
but may be overridden for more efficient traversal orders.Note: will not terminate for infinite-sized collections.
- A1
The type parameter for the binary operator, a supertype of
A
.- z
An initial value; may be used an arbitrary number of times in the computation of the result; must be a neutral value for
op
for the result to always be the same across runs.- op
A binary operator; must be associative for the result to always be the same across runs.
- returns
The result of applying
op
between all the elements andz
, orz
if this iterable collection is empty.
- Definition Classes
- IterableOnceOps
- def foldLeft[B](z: B)(op: (B, A) => B): B
Applies the given binary operator
op
to the given initial valuez
and all elements of this iterable collection, going left to right.Applies the given binary operator
op
to the given initial valuez
and all elements of this iterable collection, going left to right. Returns the initial value if this iterable collection is empty."Going left to right" only makes sense if this collection is ordered: then if
x1
,x2
, ...,xn
are the elements of this iterable collection, the result isop( op( ... op( op(z, x1), x2) ... ), xn)
.If this collection is not ordered, then for each application of the operator, each right operand is an element. In addition, the leftmost operand is the initial value, and each other left operand is itself an application of the operator. The elements of this iterable collection and the initial value all appear exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Note: will not terminate for infinite-sized collections.
- B
The result type of the binary operator.
- z
An initial value.
- op
A binary operator.
- returns
The result of applying
op
toz
and all elements of this iterable collection, going left to right. Returnsz
if this iterable collection is empty.
- Definition Classes
- IterableOnceOps
- def foldRight[B](z: B)(op: (A, B) => B): B
Applies the given binary operator
op
to all elements of this iterable collection and the given initial valuez
, going right to left.Applies the given binary operator
op
to all elements of this iterable collection and the given initial valuez
, going right to left. Returns the initial value if this iterable collection is empty."Going right to left" only makes sense if this collection is ordered: then if
x1
,x2
, ...,xn
are the elements of this iterable collection, the result isop(x1, op(x2, op( ... op(xn, z) ... )))
.If this collection is not ordered, then for each application of the operator, each left operand is an element. In addition, the rightmost operand is the initial value, and each other right operand is itself an application of the operator. The elements of this iterable collection and the initial value all appear exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Note: will not terminate for infinite-sized collections.
- B
The result type of the binary operator.
- z
An initial value.
- op
A binary operator.
- returns
The result of applying
op
to all elements of this iterable collection andz
, going right to left. Returnsz
if this iterable collection is empty.
- Definition Classes
- IterableOnceOps
- def forall(p: (A) => Boolean): Boolean
Tests whether a predicate holds for all elements of this iterable collection.
Tests whether a predicate holds for all elements of this iterable collection.
Note: may not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
true
if this iterable collection is empty or the given predicatep
holds for all elements of this iterable collection, otherwisefalse
.
- Definition Classes
- IterableOnceOps
- def foreach[U](f: (A) => U): Unit
Applies
f
to each element for its side effects.Applies
f
to each element for its side effects. Note:U
parameter needed to help scalac's type inference.- Definition Classes
- IterableOnceOps
- def groupBy[K](f: (A) => K): immutable.Map[K, C]
Partitions this iterable collection into a map of iterable collections according to some discriminator function.
Partitions this iterable collection into a map of iterable collections 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 iterable collections such that the following invariant holds:
(xs groupBy f)(k) = xs filter (x => f(x) == k)
That is, every key
k
is bound to a iterable collection of those elementsx
for whichf(x)
equalsk
.
- def groupMap[K, B](key: (A) => K)(f: (A) => B): immutable.Map[K, CC[B]]
Partitions this iterable collection into a map of iterable collections according to a discriminator function
key
.Partitions this iterable collection into a map of iterable collections according to a discriminator function
key
. Each element in a group is transformed into a value of typeB
using thevalue
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
- def groupMapReduce[K, B](key: (A) => K)(f: (A) => B)(reduce: (B, B) => B): immutable.Map[K, B]
Partitions this iterable collection into a map according to a discriminator function
key
.Partitions this iterable collection into a map according to a discriminator function
key
. All the values that have the same discriminator are then transformed by thef
function and then reduced into a single value with thereduce
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.
- def grouped(size: Int): Iterator[C]
Partitions elements in fixed size iterable collections.
Partitions elements in fixed size iterable collections.
- size
the number of elements per group
- returns
An iterator producing iterable collections of size
size
, except the last will be less than sizesize
if the elements don't divide evenly.
- See also
scala.collection.Iterator, method
grouped
- def hashCode(): Int
Calculate a hash code value for the object.
Calculate a hash code value for the object.
The default hashing algorithm is platform dependent.
Note that it is allowed for two objects to have identical hash codes (
o1.hashCode.equals(o2.hashCode)
) yet not be equal (o1.equals(o2)
returnsfalse
). A degenerate implementation could always return0
. However, it is required that if two objects are equal (o1.equals(o2)
returnstrue
) that they have identical hash codes (o1.hashCode.equals(o2.hashCode)
). Therefore, when overriding this method, be sure to verify that the behavior is consistent with theequals
method.- returns
the hash code value for this object.
- Definition Classes
- Any
- def head: A
Selects the first element of this iterable collection.
Selects the first element of this iterable collection.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
the first element of this iterable collection.
- Exceptions thrown
NoSuchElementException
if the iterable collection is empty.
- def headOption: Option[A]
Optionally selects the first element.
Optionally selects the first element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
the first element of this iterable collection if it is nonempty,
None
if it is empty.
- def init: C
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.
- def inits: Iterator[C]
Iterates over the inits of this iterable collection.
Iterates over the inits of this iterable collection. The first value will be this iterable collection and the final one will be an empty iterable collection, 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 iterable collection
List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)
Example: - def isEmpty: Boolean
Tests whether the iterable collection is empty.
Tests whether the iterable collection is empty.
Note: The default implementation creates and discards an iterator.
Note: Implementations in subclasses that are not repeatedly iterable must take care not to consume any elements when
isEmpty
is called.- returns
true
if the iterable collection contains no elements,false
otherwise.
- Definition Classes
- 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 returnstrue
if the value of the receiver object is aBigDecimal
or a subtype ofBigDecimal
.T0
is a parameterized class type, e.g.List[Int]
: this method returnstrue
if the value of the receiver object is someList[X]
for anyX
. For example,List(1, 2, 3).isInstanceOf[List[String]]
will return true.T0
is some singleton typex.type
or literalx
: this method returnsthis.eq(x)
. For example,x.isInstanceOf[1]
is equivalent tox.eq(1)
T0
is an intersectionX with Y
orX & Y: this method is equivalent to
x.isInstanceOf[X] && x.isInstanceOf[Y]T0
is a unionX | Y
: this method is equivalent tox.isInstanceOf[X] || x.isInstanceOf[Y]
T0
is a type parameter or an abstract type member: this method is equivalent toisInstanceOf[U]
whereU
isT0
's upper bound,Any
ifT0
is unbounded. For example,x.isInstanceOf[A]
whereA
is an unbounded type parameter will return true for any value ofx
.
This is exactly equivalent to the type pattern
_: T0
- returns
true
if the receiver object is an instance of erasure of typeT0
;false
otherwise.
- Definition Classes
- Any
- Note
due to the unexpectedness of
List(1, 2, 3).isInstanceOf[List[String]]
returning true andx.isInstanceOf[A]
whereA
is a type parameter or abstract member returning true, these forms issue a warning.
- def isTraversableAgain: Boolean
Tests whether this iterable collection can be repeatedly traversed.
Tests whether this iterable collection 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 knownSize: Int
The number of elements in this iterable collection, if it can be cheaply computed, -1 otherwise.
The number of elements in this iterable collection, 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.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
The last element of this iterable collection.
- Exceptions thrown
NoSuchElementException
If the iterable collection is empty.
- def lastOption: Option[A]
Optionally selects the last element.
Optionally selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
the last element of this iterable collection$ if it is nonempty,
None
if it is empty.
- def map[B](f: (A) => B): CC[B]
Builds a new iterable collection by applying a function to all elements of this iterable collection.
Builds a new iterable collection by applying a function to all elements of this iterable collection.
- B
the element type of the returned iterable collection.
- f
the function to apply to each element.
- returns
a new iterable collection resulting from applying the given function
f
to each element of this iterable collection and collecting the results.
- Definition Classes
- IterableOps → IterableOnceOps
- def max[B >: A](implicit ord: math.Ordering[B]): A
Finds the largest element.
Finds the largest element.
Note: will not terminate for infinite-sized collections.
- B
The type over which the ordering is defined.
- ord
An ordering to be used for comparing elements.
- returns
the largest element of this iterable collection with respect to the ordering
ord
.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this iterable collection is empty.
- def maxBy[B](f: (A) => B)(implicit ord: 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
.Note: will not terminate for infinite-sized collections.
- B
The result type of the function
f
.- f
The measuring function.
- returns
the first element of this iterable collection with the largest value measured by function
f
with respect to the orderingcmp
.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this iterable collection is empty.
- def maxByOption[B](f: (A) => B)(implicit ord: 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
.Note: will not terminate for infinite-sized collections.
- B
The result type of the function
f
.- f
The measuring function.
- returns
an option value containing the first element of this iterable collection with the largest value measured by function
f
with respect to the orderingcmp
.
- Definition Classes
- IterableOnceOps
- def maxOption[B >: A](implicit ord: math.Ordering[B]): Option[A]
Finds the largest element.
Finds the largest element.
Note: will not terminate for infinite-sized collections.
- 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 iterable collection 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.
Note: will not terminate for infinite-sized collections.
- B
The type over which the ordering is defined.
- ord
An ordering to be used for comparing elements.
- returns
the smallest element of this iterable collection with respect to the ordering
ord
.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this iterable collection is empty.
- def minBy[B](f: (A) => B)(implicit ord: 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
.Note: will not terminate for infinite-sized collections.
- B
The result type of the function
f
.- f
The measuring function.
- returns
the first element of this iterable collection with the smallest value measured by function
f
with respect to the orderingcmp
.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this iterable collection is empty.
- def minByOption[B](f: (A) => B)(implicit ord: 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
.Note: will not terminate for infinite-sized collections.
- B
The result type of the function
f
.- f
The measuring function.
- returns
an option value containing the first element of this iterable collection with the smallest value measured by function
f
with respect to the orderingcmp
.
- Definition Classes
- IterableOnceOps
- def minOption[B >: A](implicit ord: math.Ordering[B]): Option[A]
Finds the smallest element.
Finds the smallest element.
Note: will not terminate for infinite-sized collections.
- 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 iterable collection with respect to the ordering
ord
.
- Definition Classes
- IterableOnceOps
- final def mkString: String
Displays all elements of this iterable collection in a string.
Displays all elements of this iterable collection in a string.
Delegates to addString, which can be overridden.
- returns
a string representation of this iterable collection. In the resulting string the string representations (w.r.t. the method
toString
) of all elements of this iterable collection follow each other without any separator string.
- Definition Classes
- IterableOnceOps
- Annotations
- @inline()
- final def mkString(sep: String): String
Displays all elements of this iterable collection in a string using a separator string.
Displays all elements of this iterable collection in a string using a separator string.
Delegates to addString, which can be overridden.
- sep
the separator string.
- returns
a string representation of this iterable collection. In the resulting string the string representations (w.r.t. the method
toString
) of all elements of this iterable collection are separated by the stringsep
.
- Definition Classes
- IterableOnceOps
- Annotations
- @inline()
List(1, 2, 3).mkString("|") = "1|2|3"
Example: - final def mkString(start: String, sep: String, end: String): String
Displays all elements of this iterable collection in a string using start, end, and separator strings.
Displays all elements of this iterable collection 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 iterable collection. The resulting string begins with the string
start
and ends with the stringend
. Inside, the string representations (w.r.t. the methodtoString
) of all elements of this iterable collection are separated by the stringsep
.
- Definition Classes
- IterableOnceOps
List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
Example: - def nonEmpty: Boolean
Tests whether the iterable collection is not empty.
Tests whether the iterable collection is not empty.
- returns
true
if the iterable collection contains at least one element,false
otherwise.
- Definition Classes
- IterableOnceOps
- Annotations
- @deprecatedOverriding()
- def partition(p: (A) => Boolean): (C, C)
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.The two iterable collection correspond to the result of filter and filterNot, respectively.
The default implementation provided here needs to traverse the collection twice. Strict collections have an overridden version of
partition
inStrictOptimizedIterableOps
, which requires only a single traversal. - def partitionMap[A1, A2](f: (A) => Either[A1, A2]): (CC[A1], CC[A2])
Applies a function
f
to each element of the iterable collection and returns a pair of iterable collections: the first one made of those values returned byf
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 iterable collection and returns a pair of iterable collections: the first one made of those values returned byf
that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.Example:
val xs = Iterable(1, "one", 2, "two", 3, "three") partitionMap { case i: Int => Left(i) case s: String => Right(s) } // xs == (Iterable(1, 2, 3), // Iterable(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 iterable collection to an scala.util.Either
- returns
a pair of iterable collections: 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.
- def product[B >: A](implicit num: math.Numeric[B]): B
Multiplies together the elements of this collection.
Multiplies together the elements of this collection.
The default implementation uses
reduce
for a known non-empty collection,foldLeft
otherwise.Note: will not terminate for infinite-sized collections.
- 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 iterable collection with respect to the
*
operator innum
.
- Definition Classes
- IterableOnceOps
- def reduce[B >: A](op: (B, B) => B): B
Applies the given binary operator
op
to all elements of this iterable collection.Applies the given binary operator
op
to all elements of this iterable collection.For each application of the operator, each operand is either an element of this iterable collection or another such application of the operator. The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation.
If this collection is ordered, then for any application of the operator, the element(s) appearing in the left operand will precede those in the right.
Note: might return different results for different runs, unless either of the following conditions is met: (1) the operator is associative, and the underlying collection type is ordered; or (2) the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
- B
The type parameter for the binary operator, a supertype of
A
.- op
A binary operator; must be associative for the result to always be the same across runs.
- returns
The result of applying
op
between all the elements if the iterable collection is nonempty.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this iterable collection is empty.
- def reduceLeft[B >: A](op: (B, A) => B): B
Applies the given binary operator
op
to all elements of this iterable collection, going left to right.Applies the given binary operator
op
to all elements of this iterable collection, going left to right."Going left to right" only makes sense if this collection is ordered: then if
x1
,x2
, ...,xn
are the elements of this iterable collection, the result isop( op( op( ... op(x1, x2) ... ), xn-1), xn)
.If this collection is not ordered, then for each application of the operator, each right operand is an element. In addition, the leftmost operand is the first element of this iterable collection and each other left operand is itself an application of the operator. Each element appears exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
- B
The result type of the binary operator, a supertype of
A
.- op
A binary operator.
- returns
The result of applying
op
to all elements of this iterable collection, going left to right.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this iterable collection is empty.
- def reduceLeftOption[B >: A](op: (B, A) => B): Option[B]
If this iterable collection is nonempty, reduces it with the given binary operator
op
, going left to right.If this iterable collection is nonempty, reduces it with the given binary operator
op
, going left to right.The behavior is the same as reduceLeft except that the value is
None
if the iterable collection is empty. Each element appears exactly once in the computation.Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
- B
The result type of the binary operator, a supertype of
A
.- op
A binary operator.
- returns
The result of reducing this iterable collection with
op
going left to right if the iterable collection is nonempty, inside aSome
, andNone
otherwise.
- Definition Classes
- IterableOnceOps
- def reduceOption[B >: A](op: (B, B) => B): Option[B]
If this iterable collection is nonempty, reduces it with the given binary operator
op
.If this iterable collection is nonempty, reduces it with the given binary operator
op
.The behavior is the same as reduce except that the value is
None
if the iterable collection is empty. The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation.Note: might return different results for different runs, unless either of the following conditions is met: (1) the operator is associative, and the underlying collection type is ordered; or (2) the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
- B
A type parameter for the binary operator, a supertype of
A
.- op
A binary operator; must be associative for the result to always be the same across runs.
- returns
The result of reducing this iterable collection with
op
if the iterable collection is nonempty, inside aSome
, andNone
otherwise.
- Definition Classes
- IterableOnceOps
- def reduceRight[B >: A](op: (A, B) => B): B
Applies the given binary operator
op
to all elements of this iterable collection, going right to left.Applies the given binary operator
op
to all elements of this iterable collection, going right to left."Going right to left" only makes sense if this collection is ordered: then if
x1
,x2
, ...,xn
are the elements of this iterable collection, the result isop(x1, op(x2, op( ... op(xn-1, xn) ... )))
.If this collection is not ordered, then for each application of the operator, each left operand is an element. In addition, the rightmost operand is the last element of this iterable collection and each other right operand is itself an application of the operator. Each element appears exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
- B
The result type of the binary operator, a supertype of
A
.- op
A binary operator.
- returns
The result of applying
op
to all elements of this iterable collection, going right to left.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this iterable collection is empty.
- def reduceRightOption[B >: A](op: (A, B) => B): Option[B]
If this iterable collection is nonempty, reduces it with the given binary operator
op
, going right to left.If this iterable collection is nonempty, reduces it with the given binary operator
op
, going right to left.The behavior is the same as reduceRight except that the value is
None
if the iterable collection is empty. Each element appears exactly once in the computation.Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
- B
The result type of the binary operator, a supertype of
A
.- op
A binary operator.
- returns
The result of reducing this iterable collection with
op
going right to left if the iterable collection is nonempty, inside aSome
, andNone
otherwise.
- Definition Classes
- IterableOnceOps
- def reversed: Iterable[A]
- Attributes
- protected
- Definition Classes
- IterableOnceOps
- def scan[B >: A](z: B)(op: (B, B) => B): CC[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 iterable collection containing the prefix scan of the elements in this iterable collection
- def scanLeft[B](z: B)(op: (B, A) => B): CC[B]
Produces a iterable collection containing cumulative results of applying the operator going left to right, including the initial value.
Produces a iterable collection containing cumulative results of applying the operator going left to right, including the initial value.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- 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 → IterableOnceOps
- def scanRight[B](z: B)(op: (A, B) => B): CC[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: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
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
- def size: Int
The size of this iterable collection.
The size of this iterable collection.
Note: will not terminate for infinite-sized collections.
- returns
the number of elements in this iterable collection.
- Definition Classes
- IterableOnceOps
- def sizeCompare(that: Iterable[_]): Int
Compares the size of this iterable collection to the size of another
Iterable
.Compares the size of this iterable collection to the size of another
Iterable
.- that
the
Iterable
whose size is compared with this iterable collection's size.- returns
A value
x
wherex < 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 isO(this.size min that.size)
instead ofO(this.size + that.size)
. The method should be overridden if computingsize
is cheap andknownSize
returns-1
.
- def sizeCompare(otherSize: Int): Int
Compares the size of this iterable collection to a test value.
Compares the size of this iterable collection to a test value.
- otherSize
the test value that gets compared with the size.
- returns
A value
x
wherex < 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 isO(size min otherSize)
instead ofO(size)
. The method should be overridden if computingsize
is cheap andknownSize
returns-1
.
- See also
- final def sizeIs: SizeCompareOps
Returns a value class containing operations for comparing the size of this iterable collection to a test value.
Returns a value class containing operations for comparing the size of this iterable collection 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
- Annotations
- @inline()
- def slice(from: Int, until: Int): C
Selects an interval of elements.
Selects an interval of elements. The returned iterable collection is made up of all elements
x
which satisfy the invariant:from <= indexOf(x) < until
Note: might return different results for different runs, unless the underlying collection type is ordered.
- from
the lowest index to include from this iterable collection.
- until
the lowest index to EXCLUDE from this iterable collection.
- returns
a iterable collection containing the elements greater than or equal to index
from
extending up to (but not including) indexuntil
of this iterable collection.
- Definition Classes
- IterableOps → IterableOnceOps
- def sliding(size: Int, step: Int): Iterator[C]
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 iterable collections of size
size
, except the last element (which may be the only element) will be smaller if there are fewer thansize
elements remaining to be grouped.
List(1, 2, 3, 4, 5).sliding(2, 2) = Iterator(List(1, 2), List(3, 4), List(5))
, List(1, 2, 3, 4, 5, 6).sliding(2, 3) = Iterator(List(1, 2), List(4, 5))
- See also
scala.collection.Iterator, method
sliding
Examples: - def sliding(size: Int): Iterator[C]
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 iterable collections of size
size
, except for a non-empty collection with less thansize
elements, which returns an iterator that produces the source collection itself as its only element.
List().sliding(2) = empty iterator
, List(1).sliding(2) = Iterator(List(1))
, List(1, 2).sliding(2) = Iterator(List(1, 2))
, List(1, 2, 3).sliding(2) = Iterator(List(1, 2), List(2, 3))
- See also
scala.collection.Iterator, method
sliding
Examples: - def span(p: (A) => Boolean): (C, C)
Splits this iterable collection into a prefix/suffix pair according to a predicate.
Splits this iterable collection into a prefix/suffix pair according to a predicate.
Note:
c span p
is equivalent to (but possibly more efficient than)(c takeWhile p, c dropWhile p)
, provided the evaluation of the predicatep
does not cause any side-effects.Note: might return different results for different runs, unless the underlying collection type is ordered.
- p
the test predicate
- returns
a pair consisting of the longest prefix of this iterable collection whose elements all satisfy
p
, and the rest of this iterable collection.
- Definition Classes
- IterableOps → IterableOnceOps
- def splitAt(n: Int): (C, C)
Splits this iterable collection into a prefix/suffix pair at a given position.
Splits this iterable collection into a prefix/suffix pair at a given position.
Note:
c splitAt n
is equivalent to (but possibly more efficient than)(c take n, c drop n)
.Note: might return different results for different runs, unless the underlying collection type is ordered.
- n
the position at which to split.
- returns
a pair of iterable collections consisting of the first
n
elements of this iterable collection, and the other elements.
- Definition Classes
- IterableOps → IterableOnceOps
- 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
orChar
, an scala.collection.IntStepper is returned - For collections of
Double
orFloat
, 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
- For collections of
- def sum[B >: A](implicit num: math.Numeric[B]): B
Sums the elements of this collection.
Sums the elements of this collection.
The default implementation uses
reduce
for a known non-empty collection,foldLeft
otherwise.Note: will not terminate for infinite-sized collections.
- 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 iterable collection with respect to the
+
operator innum
.
- Definition Classes
- IterableOnceOps
- def tail: C
The rest of the collection without its first element.
- def tails: Iterator[C]
Iterates over the tails of this iterable collection.
Iterates over the tails of this iterable collection. The first value will be this iterable collection and the final one will be an empty iterable collection, with the intervening values the results of successive applications of
tail
.- returns
an iterator over all the tails of this iterable collection
List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)
Example: - def take(n: Int): C
Selects the first
n
elements.Selects the first
n
elements.Note: might return different results for different runs, unless the underlying collection type is ordered.
- n
the number of elements to take from this iterable collection.
- returns
a iterable collection consisting only of the first
n
elements of this iterable collection, or else the whole iterable collection, if it has less thann
elements. Ifn
is negative, returns an empty iterable collection.
- Definition Classes
- IterableOps → IterableOnceOps
- def takeRight(n: Int): C
Selects the last n elements.
Selects the last n elements.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- n
the number of elements to take from this iterable collection.
- returns
a iterable collection consisting only of the last
n
elements of this iterable collection, or else the whole iterable collection, if it has less thann
elements. Ifn
is negative, returns an empty iterable collection.
- def takeWhile(p: (A) => Boolean): C
Takes longest prefix of elements that satisfy a predicate.
Takes longest prefix of elements that satisfy a predicate.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- p
The predicate used to test elements.
- returns
the longest prefix of this iterable collection whose elements all satisfy the predicate
p
.
- Definition Classes
- IterableOps → IterableOnceOps
- def tapEach[U](f: (A) => U): C
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 applyf
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 iterable collection
- returns
The same logical collection as this
- Definition Classes
- IterableOps → IterableOnceOps
- def to[C1](factory: Factory[A, C1]): C1
Given a collection factory
factory
, converts this iterable collection to the appropriate representation for the current element typeA
.Given a collection factory
factory
, converts this iterable collection to the appropriate representation for the current element typeA
. 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]
Converts this iterable collection to an
Array
.Converts this iterable collection to an
Array
.Implementation note: DO NOT call Array.from from this method.
- B
The type of elements of the result, a supertype of
A
.- returns
This iterable collection as an
Array[B]
.
- Definition Classes
- IterableOnceOps
- final def toBuffer[B >: A]: Buffer[B]
Converts this iterable collection to a
Buffer
.Converts this iterable collection to a
Buffer
.- B
The type of elements of the result, a supertype of
A
.- returns
This iterable collection as a
Buffer[B]
.
- Definition Classes
- IterableOnceOps
- Annotations
- @inline()
- def toIndexedSeq: immutable.IndexedSeq[A]
Converts this iterable collection to an
IndexedSeq
.Converts this iterable collection to an
IndexedSeq
.- returns
This iterable collection as an
IndexedSeq[A]
.
- Definition Classes
- IterableOnceOps
- def toList: immutable.List[A]
Converts this iterable collection to a
List
.Converts this iterable collection to a
List
.- returns
This iterable collection as a
List[A]
.
- Definition Classes
- IterableOnceOps
- def toMap[K, V](implicit ev: <:<[A, (K, V)]): immutable.Map[K, V]
Converts this iterable collection to a
Map
, given an implicit coercion from the iterable collection's type to a key-value tuple.Converts this iterable collection to a
Map
, given an implicit coercion from the iterable collection's type to a key-value tuple.- K
The key type for the resulting map.
- V
The value type for the resulting map.
- ev
An implicit coercion from
A
to[K, V]
.- returns
This iterable collection as a
Map[K, V]
.
- Definition Classes
- IterableOnceOps
- def toSeq: immutable.Seq[A]
- returns
This iterable collection as a
Seq[A]
. This is equivalent toto(Seq)
but might be faster.
- Definition Classes
- IterableOnceOps
- def toSet[B >: A]: immutable.Set[B]
Converts this iterable collection to a
Set
.Converts this iterable collection to a
Set
.- B
The type of elements of the result, a supertype of
A
.- returns
This iterable collection as a
Set[B]
.
- Definition Classes
- IterableOnceOps
- def toString(): String
Returns a string representation of the object.
Returns a string representation of the object.
The default representation is platform dependent.
- returns
a string representation of the object.
- Definition Classes
- Any
- def toVector: immutable.Vector[A]
Converts this iterable collection to a
Vector
.Converts this iterable collection to a
Vector
.- returns
This iterable collection as a
Vector[A]
.
- Definition Classes
- IterableOnceOps
- def transpose[B](implicit asIterable: (A) => Iterable[B]): CC[CC[B]]
Transposes this iterable collection of iterable collections into a iterable collection of iterable collections.
Transposes this iterable collection of iterable collections into a iterable collection of iterable collections.
The resulting collection's type will be guided by the static type of iterable collection. For example:
val xs = List( Set(1, 2, 3), Set(4, 5, 6)).transpose // xs == List( // List(1, 4), // List(2, 5), // List(3, 6)) val ys = Vector( List(1, 2, 3), List(4, 5, 6)).transpose // ys == Vector( // Vector(1, 4), // Vector(2, 5), // Vector(3, 6))
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 iterable collection is an
Iterable
.- returns
a two-dimensional iterable collection of iterable collections which has as nth row the nth column of this iterable collection.
- Exceptions thrown
IllegalArgumentException
if all collections in this iterable collection are not of the same size.
- def unzip[A1, A2](implicit asPair: (A) => (A1, A2)): (CC[A1], CC[A2])
Converts this iterable collection of pairs into two collections of the first and second half of each pair.
Converts this iterable collection of pairs into two collections of the first and second half of each pair.
val xs = Iterable( (1, "one"), (2, "two"), (3, "three")).unzip // xs == (Iterable(1, 2, 3), // Iterable(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 iterable collection is a pair.
- returns
a pair of iterable collections, containing the first, respectively second half of each element pair of this iterable collection.
- def unzip3[A1, A2, A3](implicit asTriple: (A) => (A1, A2, A3)): (CC[A1], CC[A2], CC[A3])
Converts this iterable collection of triples into three collections of the first, second, and third element of each triple.
Converts this iterable collection of triples into three collections of the first, second, and third element of each triple.
val xs = Iterable( (1, "one", '1'), (2, "two", '2'), (3, "three", '3')).unzip3 // xs == (Iterable(1, 2, 3), // Iterable(one, two, three), // Iterable(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 iterable collection is a triple.
- returns
a triple of iterable collections, containing the first, second, respectively third member of each element triple of this iterable collection.
- def view: View[A]
A view over the elements of this collection.
- def withFilter(p: (A) => Boolean): WithFilter[A, CC]
Creates a non-strict filter of this iterable collection.
Creates a non-strict filter of this iterable collection.
Note: the difference between
c filter p
andc withFilter p
is that the former creates a new collection, whereas the latter only restricts the domain of subsequentmap
,flatMap
,foreach
, andwithFilter
operations.Note: might return different results for different runs, unless the underlying collection type is ordered.
- p
the predicate used to test elements.
- returns
an object of class
WithFilter
, which supportsmap
,flatMap
,foreach
, andwithFilter
operations. All these operations apply to those elements of this iterable collection which satisfy the predicatep
.
- def zip[B](that: IterableOnce[B]): CC[(A, B)]
Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs.
Returns a iterable collection formed from this iterable collection 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 iterable collection containing pairs consisting of corresponding elements of this iterable collection and
that
. The length of the returned collection is the minimum of the lengths of this iterable collection andthat
.
- def zipAll[A1 >: A, B](that: Iterable[B], thisElem: A1, thatElem: B): CC[(A1, B)]
Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs.
Returns a iterable collection formed from this iterable collection 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 iterable collection is shorter than
that
.- thatElem
the element to be used to fill up the result if
that
is shorter than this iterable collection.- returns
a new collection of type
That
containing pairs consisting of corresponding elements of this iterable collection andthat
. The length of the returned collection is the maximum of the lengths of this iterable collection andthat
. If this iterable collection is shorter thanthat
,thisElem
values are used to pad the result. Ifthat
is shorter than this iterable collection,thatElem
values are used to pad the result.
- def zipWithIndex: CC[(A, Int)]
Zips this iterable collection with its indices.
Zips this iterable collection with its indices.
- returns
A new iterable collection containing pairs consisting of all elements of this iterable collection paired with their index. Indices start at
0
.
- Definition Classes
- IterableOps → IterableOnceOps
List("a", "b", "c").zipWithIndex == List(("a", 0), ("b", 1), ("c", 2))
Example:
Deprecated Value Members
- def ++:[B >: A](that: IterableOnce[B]): CC[B]
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use ++ instead of ++: for collections of type Iterable
- def /:[B](z: B)(op: (B, A) => B): B
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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:(iterableOps: 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 IterableOps[A, CC, C] 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:(iterableOps: 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
Aggregates the results of applying an operator to subsequent elements.
Aggregates the results of applying an operator to subsequent elements.
Since this method degenerates to
foldLeft
for sequential (non-parallel) collections, where the combining operation is ignored, it is advisable to preferfoldLeft
for that case.For parallel collections, use the
aggregate
method specified byscala.collection.parallel.ParIterableLike
.- B
the result type, produced by
seqop
,combop
, and by this function as a final result.- z
the start value, a neutral element for
seqop
.- seqop
the binary operator used to accumulate the result.
- combop
an associative operator for combining sequential results, unused for sequential collections.
- Definition Classes
- IterableOnceOps
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) For sequential collections, prefer
foldLeft(z)(seqop)
. For parallel collections, useParIterableLike#aggregate
.
- def collectFirst[B](f: PartialFunction[A, B]): Option[B]
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).collectFirst(f)
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.collectFirst(...) instead
- def companion: IterableFactory[CC]
- 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 IterableOps[A, CC, C] 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:(iterableOps: 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 IterableOps[A, CC, C] 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:(iterableOps: 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 IterableOps[A, CC, C] 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:(iterableOps: 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 IterableOps[A, CC, C] 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:(iterableOps: 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 IterableOps[A, CC, C] 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:(iterableOps: 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 IterableOps[A, CC, C] 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:(iterableOps: 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 IterableOps[A, CC, C] 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:(iterableOps: 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 IterableOps[A, CC, C] 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:(iterableOps: 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 IterableOps[A, CC, C] 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.
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- 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 IterableOps[A, CC, C] 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.
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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 IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).foreach(f)
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @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 forString.format
(@see java.lang.String.format).- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] toStringFormat[IterableOps[A, CC, C]] performed by method StringFormat in scala.Predef.
- Definition Classes
- StringFormat
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.12.16) Use
formatString.format(value)
instead ofvalue.formatted(formatString)
, or use thef""
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 iterable collection is known to have a finite size.
Tests whether this iterable collection is known to have a finite size. All strict collections are known to have finite size. For a non-strict collection such as
Stream
, the predicate returnstrue
if all elements have been computed. It returnsfalse
if the stream is not yet evaluated to the end. Non-empty Iterators usually returnfalse
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
returnstrue
. However, checkinghasDefiniteSize
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 IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).isEmpty
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.isEmpty instead
- def map[B](f: (A) => B): IterableOnce[B]
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).map(f)
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @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
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).max(ord)
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.max instead
- def maxBy[B](f: (A) => B)(implicit cmp: math.Ordering[B]): A
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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.
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- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.maxBy(...) instead
- def min(implicit ord: math.Ordering[A]): A
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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.
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- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.min instead
- def minBy[B](f: (A) => B)(implicit cmp: math.Ordering[B]): A
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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.
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- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.minBy(...) instead
- def mkString: String
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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.
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- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.mkString instead
- def mkString(sep: String): String
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).mkString(sep)
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.mkString instead
- def mkString(start: String, sep: String, end: String): String
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).mkString(start, sep, end)
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.mkString instead
- def nonEmpty: Boolean
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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.
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- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.nonEmpty instead
- def product(implicit num: math.Numeric[A]): A
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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.
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- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.product instead
- def reduce(f: (A, A) => A): A
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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.
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- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.reduce(...) instead
- def reduceLeft(f: (A, A) => A): A
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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.
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- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.reduceLeft(...) instead
- def reduceLeftOption(f: (A, A) => A): Option[A]
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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.
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- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.reduceLeftOption(...) instead
- def reduceOption(f: (A, A) => A): Option[A]
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).reduceOption(f)
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.reduceOption(...) instead
- def reduceRight(f: (A, A) => A): A
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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.
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- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @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 IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).reduceRightOption(f)
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.reduceRightOption(...) instead
- final def repr: C
- 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 sameElements[B >: A](that: IterableOnce[B]): Boolean
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.sameElements instead
- def size: Int
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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.
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- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.size instead
- def sum(implicit num: math.Numeric[A]): A
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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.
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- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- 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 IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).to(factory)
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(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 IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).toArray(arg0)
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @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 IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).toBuffer
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.to(ArrayBuffer) instead
- def toIndexedSeq: IndexedSeq[A]
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).toIndexedSeq
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.toIndexedSeq instead
- final def toIterable: Iterable[A]
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).toIterable
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use .iterator.to(Iterable) instead
- def toIterator: Iterator[A]
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).toIterator
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @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: immutable.List[A]
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).toList
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.to(List) instead
- def toMap[K, V](implicit ev: <:<[A, (K, V)]): immutable.Map[K, V]
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).toMap(ev)
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.to(Map) instead
- def toSeq: immutable.Seq[A]
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).toSeq
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use .iterator.to(Seq) instead
- def toSet[B >: A]: immutable.Set[B]
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).toSet
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use .iterator.to(Set) instead
- def toStream: immutable.Stream[A]
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).toStream
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use .iterator.to(LazyList) instead
- final def toStream: immutable.Stream[A]
- Definition Classes
- IterableOnceOps
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use .to(LazyList) instead of .toStream
- final def toTraversable: Traversable[A]
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).toTraversable
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use .iterator.to(Iterable) instead
- final def toTraversable: Traversable[A]
Converts this iterable collection to an unspecified Iterable.
Converts this iterable collection to an unspecified Iterable. Will return the same collection if this instance is already Iterable.
- returns
An Iterable containing all elements of this iterable collection.
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) toTraversable is internal and will be made protected; its name is similar to
toList
ortoSeq
, but it doesn't copy non-immutable collections
- def toVector: immutable.Vector[A]
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).toVector
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use .iterator.to(Vector) 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.
- 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 IterableOps[A, CC, C] 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:(iterableOps: IterableOnceExtensionMethods[A]).withFilter(f)
- Definition Classes
- IterableOnceExtensionMethods
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .iterator.withFilter(...) instead
- def →[B](y: B): (IterableOps[A, CC, C], B)
- Implicit
- This member is added by an implicit conversion from IterableOps[A, CC, C] toArrowAssoc[IterableOps[A, CC, C]] performed by method ArrowAssoc in scala.Predef.
- 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.
This is the documentation for the Scala standard library.
Package structure
The scala package contains core types like
Int
,Float
,Array
orOption
which are accessible in all Scala compilation units without explicit qualification or imports.Notable packages include:
scala.collection
and its sub-packages contain Scala's collections frameworkscala.collection.immutable
- Immutable, sequential data-structures such asVector
,List
,Range
,HashMap
orHashSet
scala.collection.mutable
- Mutable, sequential data-structures such asArrayBuffer
,StringBuilder
,HashMap
orHashSet
scala.collection.concurrent
- Mutable, concurrent data-structures such asTrieMap
scala.concurrent
- Primitives for concurrent programming such asFutures
andPromises
scala.io
- Input and output operationsscala.math
- Basic math functions and additional numeric types likeBigInt
andBigDecimal
scala.sys
- Interaction with other processes and the operating systemscala.util.matching
- Regular expressionsOther packages exist. See the complete list on the right.
Additional parts of the standard library are shipped as separate libraries. These include:
scala.reflect
- Scala's reflection API (scala-reflect.jar)scala.xml
- XML parsing, manipulation, and serialization (scala-xml.jar)scala.collection.parallel
- Parallel collections (scala-parallel-collections.jar)scala.util.parsing
- Parser combinators (scala-parser-combinators.jar)scala.swing
- A convenient wrapper around Java's GUI framework called Swing (scala-swing.jar)Automatic imports
Identifiers in the scala package and the
scala.Predef
object are always in scope by default.Some of these identifiers are type aliases provided as shortcuts to commonly used classes. For example,
List
is an alias forscala.collection.immutable.List
.Other aliases refer to classes provided by the underlying platform. For example, on the JVM,
String
is an alias forjava.lang.String
.