object Empty extends Stream[Nothing]
- Source
- Stream.scala
- Alphabetic
- By Inheritance
- Empty
- Stream
- Serializable
- LinearSeq
- LinearSeqOps
- LinearSeq
- LinearSeqOps
- AbstractSeq
- Seq
- SeqOps
- Iterable
- AbstractSeq
- Seq
- Equals
- SeqOps
- PartialFunction
- Function1
- AbstractIterable
- Iterable
- IterableFactoryDefaults
- IterableOps
- IterableOnceOps
- IterableOnce
- AnyRef
- Any
- Hide All
- Show All
- Public
- Protected
Value Members
- final def !=(arg0: Any): Boolean
Test two objects for inequality.
Test two objects for inequality.
- returns
true
if !(this == that), false otherwise.
- Definition Classes
- AnyRef → Any
- final def ##: Int
Equivalent to
x.hashCode
except for boxed numeric types 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
- AnyRef → Any
- final def ++[B >: Nothing](suffix: IterableOnce[B]): Stream[B]
Alias for
concat
Alias for
concat
- Definition Classes
- IterableOps
- Annotations
- @inline()
- final def ++:[B >: Nothing](prefix: IterableOnce[B]): Stream[B]
Alias for
prependedAll
Alias for
prependedAll
- Definition Classes
- SeqOps → IterableOps
- Annotations
- @inline()
- final def +:[B >: Nothing](elem: B): Stream[B]
Alias for
prepended
. - final def :+[B >: Nothing](elem: B): Stream[B]
Alias for
appended
- final def :++[B >: Nothing](suffix: IterableOnce[B]): Stream[B]
Alias for
appendedAll
- final def ==(arg0: Any): Boolean
The expression
x == that
is equivalent toif (x eq null) that eq null else x.equals(that)
.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
- AnyRef → Any
- def addString(sb: mutable.StringBuilder, start: String, sep: String, end: String): sb.type
Appends all elements of this immutable sequence to a string builder using start, end, and separator strings.
Appends all elements of this immutable sequence 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 immutable sequence are separated by the stringsep
.Undefined elements are represented with
"_"
, an undefined tail is represented with"<not computed>"
, and cycles are represented with"<cycle>"
.- sb
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
- Stream → IterableOnceOps
- final def addString(b: mutable.StringBuilder): b.type
Appends all elements of this immutable sequence to a string builder.
Appends all elements of this immutable sequence to a string builder. The written text consists of the string representations (w.r.t. the method
toString
) of all elements of this immutable sequence 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 immutable sequence to a string builder using a separator string.
Appends all elements of this immutable sequence 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 immutable sequence, 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 andThen[C](k: PartialFunction[Nothing, C]): PartialFunction[Int, C]
Composes this partial function with another partial function that gets applied to results of this partial function.
Composes this partial function with another partial function that gets applied to results of this partial function.
Note that calling isDefinedAt on the resulting partial function may apply the first partial function and execute its side effect. For efficiency, it is recommended to call applyOrElse instead of isDefinedAt or apply.
- C
the result type of the transformation function.
- k
the transformation function
- returns
a partial function with the domain of this partial function narrowed by other partial function, which maps arguments
x
tok(this(x))
.
- Definition Classes
- PartialFunction
- def andThen[C](k: (Nothing) => C): PartialFunction[Int, C]
Composes this partial function with a transformation function that gets applied to results of this partial function.
Composes this partial function with a transformation function that gets applied to results of this partial function.
If the runtime type of the function is a
PartialFunction
then the otherandThen
method is used (note its cautions).- C
the result type of the transformation function.
- k
the transformation function
- returns
a partial function with the domain of this partial function, possibly narrowed by the specified function, which maps arguments
x
tok(this(x))
.
- Definition Classes
- PartialFunction → Function1
- def appended[B >: Nothing](elem: B): Stream[B]
A copy of this immutable sequence with an element appended.
A copy of this immutable sequence with an element appended.
Note: will not terminate for infinite-sized collections.
Example:
scala> val a = List(1) a: List[Int] = List(1) scala> val b = a :+ 2 b: List[Int] = List(1, 2) scala> println(a) List(1)
- B
the element type of the returned immutable sequence.
- elem
the appended element
- returns
a new immutable sequence consisting of all elements of this immutable sequence followed by
value
.
- Definition Classes
- SeqOps
- def appendedAll[B >: Nothing](suffix: IterableOnce[B]): Stream[B]
Returns a new immutable sequence containing the elements from the left hand operand followed by the elements from the right hand operand.
Returns a new immutable sequence containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the immutable sequence is the most specific superclass encompassing the element types of the two operands.
- B
the element type of the returned collection.
- suffix
the iterable to append.
- returns
a new collection of type
CC[B]
which contains all elements of this immutable sequence followed by all elements ofsuffix
.
- Definition Classes
- SeqOps
- def apply(n: Int): Nothing
Get the element at the specified index.
Get the element at the specified index. This operation is provided for convenience in
Seq
. It should not be assumed to be efficient unless you have anIndexedSeq
.- Definition Classes
- LinearSeqOps → SeqOps
- Annotations
- @throws(cause = scala.this.throws.<init>$default$1[IndexOutOfBoundsException])
- def applyOrElse[A1 <: Int, B1 >: Nothing](x: A1, default: (A1) => B1): B1
Applies this partial function to the given argument when it is contained in the function domain.
Applies this partial function to the given argument when it is contained in the function domain. Applies fallback function where this partial function is not defined.
Note that expression
pf.applyOrElse(x, default)
is equivalent toif(pf isDefinedAt x) pf(x) else default(x)
except that
applyOrElse
method can be implemented more efficiently. For all partial function literals the compiler generates anapplyOrElse
implementation which avoids double evaluation of pattern matchers and guards. This makesapplyOrElse
the basis for the efficient implementation for many operations and scenarios, such as:- combining partial functions into
orElse
/andThen
chains does not lead to excessiveapply
/isDefinedAt
evaluation lift
andunlift
do not evaluate source functions twice on each invocationrunWith
allows efficient imperative-style combining of partial functions with conditionally applied actions
For non-literal partial function classes with nontrivial
isDefinedAt
method it is recommended to overrideapplyOrElse
with custom implementation that avoids doubleisDefinedAt
evaluation. This may result in better performance and more predictable behavior w.r.t. side effects.- x
the function argument
- default
the fallback function
- returns
the result of this function or fallback function application.
- Definition Classes
- PartialFunction
- combining partial functions into
- final def asInstanceOf[T0]: T0
Cast the receiver object to be of type
T0
.Cast the receiver object to be of type
T0
.Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression
1.asInstanceOf[String]
will throw aClassCastException
at runtime, while the expressionList(1).asInstanceOf[List[String]]
will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.- returns
the receiver object.
- Definition Classes
- Any
- Exceptions thrown
ClassCastException
if the receiver object is not an instance of the erasure of typeT0
.
- def canEqual(that: Any): Boolean
A method that should be called from every well-designed equals method that is open to be overridden in a subclass.
A method that should be called from every well-designed equals method that is open to be overridden in a subclass. See Programming in Scala, Chapter 28 for discussion and design.
- that
the value being probed for possible equality
- returns
true if this instance can possibly equal
that
, otherwise false
- def className: String
Defines the prefix of this object's
toString
representation.Defines the prefix of this object's
toString
representation.It is recommended to return the name of the concrete collection type, but not implementation subclasses. For example, for
ListMap
this method should return"ListMap"
, not"Map"
(the supertype) or"Node"
(an implementation subclass).The default implementation returns "Iterable". It is overridden for the basic collection kinds "Seq", "IndexedSeq", "LinearSeq", "Buffer", "Set", "Map", "SortedSet", "SortedMap" and "View".
- returns
a string representation which starts the result of
toString
applied to this immutable sequence. By default the string prefix is the simple name of the collection class immutable sequence.
- def clone(): AnyRef
Create a copy of the receiver object.
Create a copy of the receiver object.
The default implementation of the
clone
method is platform dependent.- returns
a copy of the receiver object.
- final def coll: Empty.this.type
- returns
This collection as a
C
.
- Attributes
- protected
- Definition Classes
- Iterable → IterableOps
- final def collect[B](pf: PartialFunction[Nothing, B]): Stream[B]
Builds a new immutable sequence by applying a partial function to all elements of this immutable sequence on which the function is defined.
Builds a new immutable sequence by applying a partial function to all elements of this immutable sequence on which the function is defined.
- B
the element type of the returned immutable sequence.
- pf
the partial function which filters and maps the immutable sequence.
- returns
a new immutable sequence 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
- Stream → IterableOps → IterableOnceOps
- Annotations
- @tailrec()
- final def collectFirst[B](pf: PartialFunction[Nothing, B]): Option[B]
Finds the first element of the immutable sequence for which the given partial function is defined, and applies the partial function to it.
Finds the first element of the immutable sequence for which the given partial function is defined, and applies the partial function to it.
Note: may not terminate for infinite-sized collections.
- 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
- Stream → IterableOnceOps
- Annotations
- @tailrec()
Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)
Example: - def combinations(n: Int): Iterator[Stream[Nothing]]
Iterates over combinations of elements.
Iterates over combinations of elements.
A combination of length
n
is a sequence ofn
elements selected in order of their first index in this sequence.For example,
"xyx"
has two combinations of length 2. Thex
is selected first:"xx"
,"xy"
. The sequence"yx"
is not returned as a combination because it is subsumed by"xy"
.If there is more than one way to generate the same combination, only one will be returned.
For example, the result
"xy"
arbitrarily selected one of thex
elements.As a further illustration,
"xyxx"
has three different ways to generate"xy"
because there are three elementsx
to choose from. Moreover, there are three unordered pairs"xx"
but only one is returned.It is not specified which of these equal combinations is returned. It is an implementation detail that should not be relied on. For example, the combination
"xx"
does not necessarily contain the firstx
in this sequence. This behavior is observable if the elements compare equal but are not identical.As a consequence,
"xyx".combinations(3).next()
is"xxy"
: the combination does not reflect the order of the original sequence, but the order in which elements were selected, by "first index"; the order of eachx
element is also arbitrary.Note: Even when applied to a view or a lazy collection it will always force the elements.
- returns
An Iterator which traverses the n-element combinations of this immutable sequence.
- Definition Classes
- SeqOps
Seq('a', 'b', 'b', 'b', 'c').combinations(2).foreach(println) // List(a, b) // List(a, c) // List(b, b) // List(b, c) Seq('b', 'a', 'b').combinations(2).foreach(println) // List(b, b) // List(b, a)
Example: - def compose[R](k: PartialFunction[R, Int]): PartialFunction[R, Nothing]
Composes another partial function
k
with this partial function so that this partial function gets applied to results ofk
.Composes another partial function
k
with this partial function so that this partial function gets applied to results ofk
.Note that calling isDefinedAt on the resulting partial function may apply the first partial function and execute its side effect. For efficiency, it is recommended to call applyOrElse instead of isDefinedAt or apply.
- R
the parameter type of the transformation function.
- k
the transformation function
- returns
a partial function with the domain of other partial function narrowed by this partial function, which maps arguments
x
tothis(k(x))
.
- Definition Classes
- PartialFunction
- def compose[A](g: (A) => Int): (A) => Nothing
Composes two instances of Function1 in a new Function1, with this function applied last.
Composes two instances of Function1 in a new Function1, with this function applied last.
- A
the type to which function
g
can be applied- g
a function A => T1
- returns
a new function
f
such thatf(x) == apply(g(x))
- Definition Classes
- Function1
- Annotations
- @unspecialized()
- final def concat[B >: Nothing](suffix: IterableOnce[B]): Stream[B]
Returns a new immutable sequence containing the elements from the left hand operand followed by the elements from the right hand operand.
Returns a new immutable sequence containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the immutable sequence is the most specific superclass encompassing the element types of the two operands.
- B
the element type of the returned collection.
- suffix
the traversable to append.
- returns
a new immutable sequence which contains all elements of this immutable sequence followed by all elements of
suffix
.
- Definition Classes
- SeqOps → IterableOps
- Annotations
- @inline()
- def contains[A1 >: Nothing](elem: A1): Boolean
Tests whether this immutable sequence contains a given value as an element.
Tests whether this immutable sequence contains a given value as an element.
Note: may not terminate for infinite-sized collections.
- elem
the element to test.
- returns
true
if this immutable sequence has an element that is equal (as determined by==
) toelem
,false
otherwise.
- Definition Classes
- LinearSeqOps → SeqOps
- def containsSlice[B >: Nothing](that: collection.Seq[B]): Boolean
Tests whether this immutable sequence contains a given sequence as a slice.
Tests whether this immutable sequence contains a given sequence as a slice.
Note: may not terminate for infinite-sized collections.
- that
the sequence to test
- returns
true
if this immutable sequence contains a slice with the same elements asthat
, otherwisefalse
.
- Definition Classes
- SeqOps
- def copyToArray[B >: Nothing](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 immutable sequence.Copying will stop once either all the elements of this immutable sequence 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 >: Nothing](xs: Array[B], start: Int): Int
Copy elements to an array, returning the number of elements written.
Copy elements to an array, returning the number of elements written.
Fills the given array
xs
starting at indexstart
with values of this immutable sequence.Copying will stop once either all the elements of this immutable sequence 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 >: Nothing](xs: Array[B]): Int
Copy elements to an array, returning the number of elements written.
Copy elements to an array, returning the number of elements written.
Fills the given array
xs
starting at indexstart
with values of this immutable sequence.Copying will stop once either all the elements of this immutable sequence have been copied, or the end of the array is reached.
- B
the type of the elements of the array.
- xs
the array to fill.
- returns
the number of elements written to the array
- Definition Classes
- IterableOnceOps
- Annotations
- @deprecatedOverriding()
- Note
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
- def corresponds[B](that: collection.Seq[B])(p: (Nothing, B) => Boolean): Boolean
Tests whether every element of this immutable sequence relates to the corresponding element of another sequence by satisfying a test predicate.
Tests whether every element of this immutable sequence relates to the corresponding element of another sequence by satisfying a test predicate.
- B
the type of the elements of
that
- that
the other sequence
- p
the test predicate, which relates elements from both sequences
- returns
true
if both sequences have the same length andp(x, y)
istrue
for all corresponding elementsx
of this immutable sequence andy
ofthat
, otherwisefalse
.
- Definition Classes
- SeqOps
- def corresponds[B](that: IterableOnce[B])(p: (Nothing, 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: (Nothing) => Boolean): Int
Counts the number of elements in the immutable sequence which satisfy a predicate.
Counts the number of elements in the immutable sequence 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 diff[B >: Nothing](that: collection.Seq[B]): Stream[Nothing]
Computes the multiset difference between this immutable sequence and another sequence.
Computes the multiset difference between this immutable sequence and another sequence.
- that
the sequence of elements to remove
- returns
a new immutable sequence which contains all elements of this immutable sequence except some of occurrences of elements that also appear in
that
. If an element valuex
appears n times inthat
, then the first n occurrences ofx
will not form part of the result, but any following occurrences will.
- Definition Classes
- SeqOps
- def distinct: Stream[Nothing]
Selects all the elements of this immutable sequence ignoring the duplicates.
Selects all the elements of this immutable sequence ignoring the duplicates.
- returns
a new immutable sequence consisting of all the elements of this immutable sequence without duplicates.
- Definition Classes
- SeqOps
- def distinctBy[B](f: (Nothing) => B): Stream[Nothing]
Selects all the elements of this immutable sequence ignoring the duplicates as determined by
==
after applying the transforming functionf
.Selects all the elements of this immutable sequence ignoring the duplicates as determined by
==
after applying the transforming functionf
.- B
the type of the elements after being transformed by
f
- f
The transforming function whose result is used to determine the uniqueness of each element
- returns
a new immutable sequence consisting of all the elements of this immutable sequence without duplicates.
- Definition Classes
- SeqOps
- def drop(n: Int): Stream[Nothing]
Selects all elements except first n ones.
Selects all elements except first n ones.
- n
the number of elements to drop from this immutable sequence.
- returns
a immutable sequence consisting of all elements of this immutable sequence except the first
n
ones, or else the empty immutable sequence, if this immutable sequence has less thann
elements. Ifn
is negative, don't drop any elements.
- Definition Classes
- IterableOps → IterableOnceOps
- def dropRight(n: Int): Stream[Nothing]
Selects all elements except last n ones.
Selects all elements except last n ones.
- n
the number of elements to drop from this immutable sequence.
- returns
a immutable sequence consisting of all elements of this immutable sequence except the last
n
ones, or else the empty immutable sequence, if this immutable sequence has less thann
elements. Ifn
is negative, don't drop any elements.
- Definition Classes
- IterableOps
- def dropWhile(p: (Nothing) => Boolean): Stream[Nothing]
Drops longest prefix of elements that satisfy a predicate.
Drops longest prefix of elements that satisfy a predicate.
- p
The predicate used to test elements.
- returns
the longest suffix of this immutable sequence whose first element does not satisfy the predicate
p
.
- Definition Classes
- IterableOps → IterableOnceOps
- def elementWise: ElementWiseExtractor[Int, Nothing]
Returns an extractor object with a
unapplySeq
method, which extracts each element of a sequence data.Returns an extractor object with a
unapplySeq
method, which extracts each element of a sequence data.- Definition Classes
- PartialFunction
val firstChar: String => Option[Char] = _.headOption Seq("foo", "bar", "baz") match { case firstChar.unlift.elementWise(c0, c1, c2) => println(s"$c0, $c1, $c2") // Output: f, b, b }
Example: - def empty: Stream[Nothing]
The empty iterable of the same type as this iterable
The empty iterable of the same type as this iterable
- returns
an empty iterable of type
C
.
- Definition Classes
- IterableFactoryDefaults → IterableOps
- def endsWith[B >: Nothing](that: collection.Iterable[B]): Boolean
Tests whether this immutable sequence ends with the given sequence.
Tests whether this immutable sequence ends with the given sequence.
Note: will not terminate for infinite-sized collections.
- that
the sequence to test
- returns
true
if this immutable sequence hasthat
as a suffix,false
otherwise.
- Definition Classes
- SeqOps
- final def eq(arg0: AnyRef): Boolean
Tests whether the argument (
that
) is a reference to the receiver object (this
).Tests whether the argument (
that
) is a reference to the receiver object (this
).The
eq
method implements an equivalence relation on non-null instances ofAnyRef
, and has three additional properties:- It is consistent: for any non-null instances
x
andy
of typeAnyRef
, multiple invocations ofx.eq(y)
consistently returnstrue
or consistently returnsfalse
. - For any non-null instance
x
of typeAnyRef
,x.eq(null)
andnull.eq(x)
returnsfalse
. null.eq(null)
returnstrue
.
When overriding the
equals
orhashCode
methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2
), they should be equal to each other (o1 == o2
) and they should hash to the same value (o1.hashCode == o2.hashCode
).- returns
true
if the argument is a reference to the receiver object;false
otherwise.
- Definition Classes
- AnyRef
- It is consistent: for any non-null instances
- def equals(o: Any): Boolean
The universal equality method defined in
AnyRef
. - def exists(p: (Nothing) => Boolean): Boolean
Tests whether a predicate holds for at least one element of this immutable sequence.
Tests whether a predicate holds for at least one element of this immutable sequence.
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 immutable sequence, otherwisefalse
- Definition Classes
- LinearSeqOps → IterableOnceOps
- def filter(pred: (Nothing) => Boolean): Stream[Nothing]
Selects all elements of this immutable sequence which satisfy a predicate.
Selects all elements of this immutable sequence which satisfy a predicate.
- returns
a new immutable sequence consisting of all elements of this immutable sequence that satisfy the given predicate
p
. The order of the elements is preserved.
- Definition Classes
- Stream → IterableOps → IterableOnceOps
- def filterNot(pred: (Nothing) => Boolean): Stream[Nothing]
Selects all elements of this immutable sequence which do not satisfy a predicate.
Selects all elements of this immutable sequence which do not satisfy a predicate.
- pred
the predicate used to test elements.
- returns
a new immutable sequence consisting of all elements of this immutable sequence that do not satisfy the given predicate
pred
. Their order may not be preserved.
- Definition Classes
- Stream → IterableOps → IterableOnceOps
- def finalize(): Unit
Called by the garbage collector on the receiver object when there are no more references to the object.
Called by the garbage collector on the receiver object when there are no more references to the object.
The details of when and if the
finalize
method is invoked, as well as the interaction betweenfinalize
and non-local returns and exceptions, are all platform dependent.- Attributes
- protected[lang]
- Definition Classes
- AnyRef
- Annotations
- @throws(classOf[java.lang.Throwable])
- Note
not specified by SLS as a member of AnyRef
- final def find(p: (Nothing) => Boolean): Option[Nothing]
Finds the first element of the immutable sequence satisfying a predicate, if any.
Finds the first element of the immutable sequence satisfying a predicate, if any.
Note: may not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
an option value containing the first element in the immutable sequence that satisfies
p
, orNone
if none exists.
- Definition Classes
- Stream → LinearSeqOps → IterableOnceOps
- Annotations
- @tailrec()
- def findLast(p: (Nothing) => Boolean): Option[Nothing]
Finds the last element of the immutable sequence satisfying a predicate, if any.
Finds the last element of the immutable sequence satisfying a predicate, if any.
Note: will not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
an option value containing the last element in the immutable sequence that satisfies
p
, orNone
if none exists.
- Definition Classes
- LinearSeqOps → SeqOps
- final def flatMap[B](f: (Nothing) => IterableOnce[B]): Stream[B]
Builds a new immutable sequence by applying a function to all elements of this immutable sequence and using the elements of the resulting collections.
Builds a new immutable sequence by applying a function to all elements of this immutable sequence 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 immutable sequence. 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 immutable sequence resulting from applying the given collection-valued function
f
to each element of this immutable sequence and concatenating the results.
- Definition Classes
- Stream → IterableOps → IterableOnceOps
- def flatten[B](implicit asIterable: (Nothing) => IterableOnce[B]): Stream[B]
Converts this immutable sequence of traversable collections into a immutable sequence formed by the elements of these traversable collections.
Converts this immutable sequence of traversable collections into a immutable sequence formed by the elements of these traversable collections.
The resulting collection's type will be guided by the type of immutable sequence. For example:
val xs = List( Set(1, 2, 3), Set(1, 2, 3) ).flatten // xs == List(1, 2, 3, 1, 2, 3) val ys = Set( List(1, 2, 3), List(3, 2, 1) ).flatten // ys == Set(1, 2, 3)
- B
the type of the elements of each traversable collection.
- asIterable
an implicit conversion which asserts that the element type of this immutable sequence is a
GenTraversable
.- returns
a new immutable sequence resulting from concatenating all element immutable sequences.
- Definition Classes
- IterableOps → IterableOnceOps
- def fold[A1 >: Nothing](z: A1)(op: (A1, A1) => A1): A1
Folds the elements of this immutable sequence using the specified associative binary operator.
Folds the elements of this immutable sequence using the specified associative binary operator. The default implementation in
IterableOnce
is equivalent tofoldLeft
but may be overridden for more efficient traversal orders.The order in which operations are performed on elements is unspecified and may be nondeterministic.
Note: will not terminate for infinite-sized collections.
- A1
a type parameter for the binary operator, a supertype of
A
.- z
a neutral element for the fold operation; may be added to the result an arbitrary number of times, and must not change the result (e.g.,
Nil
for list concatenation, 0 for addition, or 1 for multiplication).- op
a binary operator that must be associative.
- returns
the result of applying the fold operator
op
between all the elements andz
, orz
if this immutable sequence is empty.
- Definition Classes
- IterableOnceOps
- final def foldLeft[B](z: B)(op: (B, Nothing) => B): B
Stream specialization of foldLeft which allows GC to collect along the way.
Stream specialization of foldLeft which allows GC to collect along the way.
- B
The type of value being accumulated.
- z
The initial value seeded into the function
op
.- op
The operation to perform on successive elements of the
Stream
.- returns
The accumulated value from successive applications of
op
.
- Definition Classes
- Stream → LinearSeqOps → IterableOnceOps
- Annotations
- @tailrec()
- def foldRight[B](z: B)(op: (Nothing, B) => B): B
Applies a binary operator to all elements of this immutable sequence and a start value, going right to left.
Applies a binary operator to all elements of this immutable sequence and a start value, going right to left.
Note: will not terminate for infinite-sized collections.
- B
the result type of the binary operator.
- z
the start value.
- op
the binary operator.
- returns
the result of inserting
op
between consecutive elements of this immutable sequence, going right to left with the start valuez
on the right:op(x1, op(x2, ... op(xn, z)...))
wherex1, ..., xn
are the elements of this immutable sequence. Returnsz
if this immutable sequence is empty.
- Definition Classes
- IterableOnceOps
- def forall(p: (Nothing) => Boolean): Boolean
Tests whether a predicate holds for all elements of this immutable sequence.
Tests whether a predicate holds for all elements of this immutable sequence.
Note: may not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
true
if this immutable sequence is empty or the given predicatep
holds for all elements of this immutable sequence, otherwisefalse
.
- Definition Classes
- LinearSeqOps → IterableOnceOps
- def force: Empty.this.type
Forces evaluation of the whole
Stream
and returns it.Forces evaluation of the whole
Stream
and returns it.- returns
The fully realized
Stream
.
- final def foreach[U](f: (Nothing) => U): Unit
Apply the given function
f
to each element of this linear sequence (while respecting the order of the elements).Apply the given function
f
to each element of this linear sequence (while respecting the order of the elements).- f
The treatment to apply to each element.
- Definition Classes
- Stream → LinearSeqOps → IterableOnceOps
- Annotations
- @tailrec()
- Note
Overridden here as final to trigger tail-call optimization, which replaces 'this' with 'tail' at each iteration. This is absolutely necessary for allowing the GC to collect the underlying Stream as elements are consumed.
,This function will force the realization of the entire Stream unless the
f
throws an exception.
- def fromSpecific(coll: IterableOnce[Nothing]): Stream[Nothing]
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
- Definition Classes
- IterableFactoryDefaults → IterableOps
- Note
When implementing a custom collection type and refining
,C
to the new type, this method needs to be overridden (the compiler will issue an error otherwise). In the common case 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.
- final def getClass(): Class[_ <: AnyRef]
Returns the runtime class representation of the object.
- def groupBy[K](f: (Nothing) => K): Map[K, Stream[Nothing]]
Partitions this immutable sequence into a map of immutable sequences according to some discriminator function.
Partitions this immutable sequence into a map of immutable sequences 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 immutable sequences 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 immutable sequence of those elementsx
for whichf(x)
equalsk
.
- Definition Classes
- IterableOps
- def groupMap[K, B](key: (Nothing) => K)(f: (Nothing) => B): Map[K, Stream[B]]
Partitions this immutable sequence into a map of immutable sequences according to a discriminator function
key
.Partitions this immutable sequence into a map of immutable sequences 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
- Definition Classes
- IterableOps
- def groupMapReduce[K, B](key: (Nothing) => K)(f: (Nothing) => B)(reduce: (B, B) => B): Map[K, B]
Partitions this immutable sequence into a map according to a discriminator function
key
.Partitions this immutable sequence 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.
- Definition Classes
- IterableOps
- def grouped(size: Int): Iterator[Stream[Nothing]]
Partitions elements in fixed size immutable sequences.
Partitions elements in fixed size immutable sequences.
- size
the number of elements per group
- returns
An iterator producing immutable sequences of size
size
, except the last will be less than sizesize
if the elements don't divide evenly.
- Definition Classes
- IterableOps
- See also
scala.collection.Iterator, method
grouped
- def hashCode(): Int
The hashCode method for reference types.
- def head: Nothing
<invalid inheritdoc annotation>
<invalid inheritdoc annotation>
Note: *Must* be overridden in subclasses. The default implementation is inherited from IterableOps.
- Definition Classes
- Empty → LinearSeqOps → IterableOps
- def headOption: Option[Nothing]
Optionally selects the first element.
Optionally selects the first element.
- returns
the first element of this immutable sequence if it is nonempty,
None
if it is empty.
- Definition Classes
- LinearSeqOps → IterableOps
- def indexOf[B >: Nothing](elem: B): Int
Finds index of first occurrence of some value in this immutable sequence.
Finds index of first occurrence of some value in this immutable sequence.
- B
the type of the element
elem
.- elem
the element value to search for.
- returns
the index
>= 0
of the first element of this immutable sequence that is equal (as determined by==
) toelem
, or-1
, if none exists.
- Definition Classes
- SeqOps
- Annotations
- @deprecatedOverriding()
- def indexOf[B >: Nothing](elem: B, from: Int): Int
Finds index of first occurrence of some value in this immutable sequence after or at some start index.
Finds index of first occurrence of some value in this immutable sequence after or at some start index.
- B
the type of the element
elem
.- elem
the element value to search for.
- from
the start index
- returns
the index
>= from
of the first element of this immutable sequence that is equal (as determined by==
) toelem
, or-1
, if none exists.
- Definition Classes
- SeqOps
- def indexOfSlice[B >: Nothing](that: collection.Seq[B]): Int
Finds first index where this immutable sequence contains a given sequence as a slice.
Finds first index where this immutable sequence contains a given sequence as a slice.
Note: may not terminate for infinite-sized collections.
- that
the sequence to test
- returns
the first index
>= 0
such that the elements of this immutable sequence starting at this index match the elements of sequencethat
, or-1
if no such subsequence exists.
- Definition Classes
- SeqOps
- Annotations
- @deprecatedOverriding()
- def indexOfSlice[B >: Nothing](that: collection.Seq[B], from: Int): Int
Finds first index after or at a start index where this immutable sequence contains a given sequence as a slice.
Finds first index after or at a start index where this immutable sequence contains a given sequence as a slice.
Note: may not terminate for infinite-sized collections.
- that
the sequence to test
- from
the start index
- returns
the first index
>= from
such that the elements of this immutable sequence starting at this index match the elements of sequencethat
, or-1
if no such subsequence exists.
- Definition Classes
- SeqOps
- def indexWhere(p: (Nothing) => Boolean, from: Int): Int
Finds index of the first element satisfying some predicate after or at some start index.
Finds index of the first element satisfying some predicate after or at some start index.
Note: may not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- from
the start index
- returns
the index
>= from
of the first element of this immutable sequence that satisfies the predicatep
, or-1
, if none exists.
- Definition Classes
- LinearSeqOps → SeqOps
- def indexWhere(p: (Nothing) => Boolean): Int
Finds index of the first element satisfying some predicate.
Finds index of the first element satisfying some predicate.
Note: may not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
the index
>= 0
of the first element of this immutable sequence that satisfies the predicatep
, or-1
, if none exists.
- Definition Classes
- SeqOps
- Annotations
- @deprecatedOverriding()
- def indices: Range
Produces the range of all indices of this sequence.
Produces the range of all indices of this sequence.
Note: Even when applied to a view or a lazy collection it will always force the elements.
- returns
a
Range
value from0
to one less than the length of this immutable sequence.
- Definition Classes
- SeqOps
- def init: Stream[Nothing]
The initial part of the collection without its last element.
The initial part of the collection without its last element.
Note: Even when applied to a view or a lazy collection it will always force the elements.
- Definition Classes
- IterableOps
- def inits: Iterator[Stream[Nothing]]
Iterates over the inits of this immutable sequence.
Iterates over the inits of this immutable sequence. The first value will be this immutable sequence and the final one will be an empty immutable sequence, 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 immutable sequence
- Definition Classes
- IterableOps
List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)
Example: - def intersect[B >: Nothing](that: collection.Seq[B]): Stream[Nothing]
Computes the multiset intersection between this immutable sequence and another sequence.
Computes the multiset intersection between this immutable sequence and another sequence.
- that
the sequence of elements to intersect with.
- returns
a new immutable sequence which contains all elements of this immutable sequence which also appear in
that
. If an element valuex
appears n times inthat
, then the first n occurrences ofx
will be retained in the result, but any following occurrences will be omitted.
- Definition Classes
- SeqOps
- def isDefinedAt(x: Int): Boolean
Tests whether this immutable sequence contains given index.
Tests whether this immutable sequence contains given index.
The implementations of methods
apply
andisDefinedAt
turn aSeq[A]
into aPartialFunction[Int, A]
.- returns
true
if this immutable sequence contains an element at positionidx
,false
otherwise.
- Definition Classes
- LinearSeqOps → SeqOps
- def isEmpty: Boolean
<invalid inheritdoc annotation>
<invalid inheritdoc annotation>
Note: *Must* be overridden in subclasses. The default implementation that is inherited from SeqOps uses
lengthCompare
, which is defined here to useisEmpty
.- Definition Classes
- Empty → LinearSeqOps → SeqOps → IterableOnceOps
- final def isInstanceOf[T0]: Boolean
Test whether the dynamic type of the receiver object has the same erasure as
T0
.Test whether the dynamic type of the receiver object has the same erasure as
T0
.Depending on what
T0
is, the test is done in one of the below ways:T0
is a non-parameterized class type, e.g.BigDecimal
: this method 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 immutable sequence can be repeatedly traversed.
Tests whether this immutable sequence can be repeatedly traversed. Always true for Iterables and false for Iterators unless overridden.
- returns
true
if it is repeatedly traversable,false
otherwise.
- Definition Classes
- IterableOps → IterableOnceOps
- def iterableFactory: SeqFactory[Stream]
The companion object of this immutable sequence, providing various factory methods.
The companion object of this immutable sequence, providing various factory methods.
- def iterator: Iterator[Nothing]
Iterator can be used only once
Iterator can be used only once
- Definition Classes
- LinearSeqOps → IterableOnce
- def knownSize: Int
- returns
The number of elements in this immutable sequence, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.
- Definition Classes
- Empty → IterableOnce
- def last: Nothing
Selects the last element.
Selects the last element.
- returns
The last element of this immutable sequence.
- Definition Classes
- LinearSeqOps → IterableOps
- Exceptions thrown
NoSuchElementException
If the immutable sequence is empty.
- def lastIndexOf[B >: Nothing](elem: B, end: Int = length - 1): Int
Finds index of last occurrence of some value in this immutable sequence before or at a given end index.
Finds index of last occurrence of some value in this immutable sequence before or at a given end index.
Note: will not terminate for infinite-sized collections.
- B
the type of the element
elem
.- elem
the element value to search for.
- end
the end index.
- returns
the index
<= end
of the last element of this immutable sequence that is equal (as determined by==
) toelem
, or-1
, if none exists.
- Definition Classes
- SeqOps
- def lastIndexOfSlice[B >: Nothing](that: collection.Seq[B]): Int
Finds last index where this immutable sequence contains a given sequence as a slice.
Finds last index where this immutable sequence contains a given sequence as a slice.
Note: will not terminate for infinite-sized collections.
- that
the sequence to test
- returns
the last index such that the elements of this immutable sequence starting at this index match the elements of sequence
that
, or-1
if no such subsequence exists.
- Definition Classes
- SeqOps
- Annotations
- @deprecatedOverriding()
- def lastIndexOfSlice[B >: Nothing](that: collection.Seq[B], end: Int): Int
Finds last index before or at a given end index where this immutable sequence contains a given sequence as a slice.
Finds last index before or at a given end index where this immutable sequence contains a given sequence as a slice.
Note: will not terminate for infinite-sized collections.
- that
the sequence to test
- end
the end index
- returns
the last index
<= end
such that the elements of this immutable sequence starting at this index match the elements of sequencethat
, or-1
if no such subsequence exists.
- Definition Classes
- SeqOps
- def lastIndexWhere(p: (Nothing) => Boolean, end: Int): Int
Finds index of last element satisfying some predicate before or at given end index.
Finds index of last element satisfying some predicate before or at given end index.
Note: will not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
the index
<= end
of the last element of this immutable sequence that satisfies the predicatep
, or-1
, if none exists.
- Definition Classes
- LinearSeqOps → SeqOps
- def lastIndexWhere(p: (Nothing) => Boolean): Int
Finds index of last element satisfying some predicate.
Finds index of last element satisfying some predicate.
Note: will not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
the index of the last element of this immutable sequence that satisfies the predicate
p
, or-1
, if none exists.
- Definition Classes
- SeqOps
- Annotations
- @deprecatedOverriding()
- def lastOption: Option[Nothing]
Optionally selects the last element.
Optionally selects the last element.
- returns
the last element of this immutable sequence$ if it is nonempty,
None
if it is empty.
- Definition Classes
- IterableOps
- def lazyAppendedAll[B >: Nothing](suffix: => IterableOnce[B]): Stream[B]
The stream resulting from the concatenation of this stream with the argument stream.
The stream resulting from the concatenation of this stream with the argument stream.
- suffix
The collection that gets appended to this stream
- returns
The stream containing elements of this stream and the iterable object.
- Definition Classes
- Stream
- def lazyZip[B](that: collection.Iterable[B]): LazyZip2[Nothing, B, Empty.this.type]
Analogous to
zip
except that the elements in each collection are not consumed until a strict operation is invoked on the returnedLazyZip2
decorator.Analogous to
zip
except that the elements in each collection are not consumed until a strict operation is invoked on the returnedLazyZip2
decorator.Calls to
lazyZip
can be chained to support higher arities (up to 4) without incurring the expense of constructing and deconstructing intermediary tuples.val xs = List(1, 2, 3) val res = (xs lazyZip xs lazyZip xs lazyZip xs).map((a, b, c, d) => a + b + c + d) // res == List(4, 8, 12)
- B
the type of the second element in each eventual pair
- that
the iterable providing the second element of each eventual pair
- returns
a decorator
LazyZip2
that allows strict operations to be performed on the lazily evaluated pairs or chained calls tolazyZip
. Implicit conversion toIterable[(A, B)]
is also supported.
- Definition Classes
- Iterable
- def length: Int
The length (number of elements) of the immutable sequence.
The length (number of elements) of the immutable sequence.
size
is an alias forlength
inSeq
collections.- Definition Classes
- LinearSeqOps → SeqOps
- def lengthCompare(that: collection.Iterable[_]): Int
Compares the length of this immutable sequence to the size of another
Iterable
.Compares the length of this immutable sequence to the size of another
Iterable
.- that
the
Iterable
whose size is compared with this immutable sequence's length.- returns
A value
x
wherex < 0 if this.length < that.size x == 0 if this.length == that.size x > 0 if this.length > that.size
The method as implemented here does not call
length
orsize
directly; its running time isO(this.length min that.size)
instead ofO(this.length + that.size)
. The method should be overridden if computingsize
is cheap andknownSize
returns-1
.
- Definition Classes
- LinearSeqOps → SeqOps
- def lengthCompare(len: Int): Int
Compares the length of this immutable sequence to a test value.
Compares the length of this immutable sequence to a test value.
- len
the test value that gets compared with the length.
- returns
A value
x
wherex < 0 if this.length < len x == 0 if this.length == len x > 0 if this.length > len
The method as implemented here does not call
length
directly; its running time isO(length min len)
instead ofO(length)
. The method should be overridden if computinglength
is cheap andknownSize
returns-1
.
- Definition Classes
- LinearSeqOps → SeqOps
- See also
- final def lengthIs: SizeCompareOps
Returns a value class containing operations for comparing the length of this immutable sequence to a test value.
Returns a value class containing operations for comparing the length of this immutable sequence to a test value.
These operations are implemented in terms of
lengthCompare(Int)
, and allow the following more readable usages:this.lengthIs < len // this.lengthCompare(len) < 0 this.lengthIs <= len // this.lengthCompare(len) <= 0 this.lengthIs == len // this.lengthCompare(len) == 0 this.lengthIs != len // this.lengthCompare(len) != 0 this.lengthIs >= len // this.lengthCompare(len) >= 0 this.lengthIs > len // this.lengthCompare(len) > 0
- def lift: (Int) => Option[Nothing]
Turns this partial function into a plain function returning an
Option
result.Turns this partial function into a plain function returning an
Option
result.- returns
a function that takes an argument
x
toSome(this(x))
ifthis
is defined forx
, and toNone
otherwise.
- Definition Classes
- PartialFunction
- See also
Function.unlift
- final def map[B](f: (Nothing) => B): Stream[B]
Builds a new immutable sequence by applying a function to all elements of this immutable sequence.
Builds a new immutable sequence by applying a function to all elements of this immutable sequence.
- B
the element type of the returned immutable sequence.
- f
the function to apply to each element.
- returns
a new immutable sequence resulting from applying the given function
f
to each element of this immutable sequence and collecting the results.
- Definition Classes
- Stream → IterableOps → IterableOnceOps
- def max[B >: Nothing](implicit ord: math.Ordering[B]): Nothing
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 immutable sequence with respect to the ordering
ord
.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this immutable sequence is empty.
- def maxBy[B](f: (Nothing) => B)(implicit cmp: math.Ordering[B]): Nothing
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.
- cmp
An ordering to be used for comparing elements.
- returns
the first element of this immutable sequence with the largest value measured by function f with respect to the ordering
cmp
.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this immutable sequence is empty.
- def maxByOption[B](f: (Nothing) => B)(implicit cmp: math.Ordering[B]): Option[Nothing]
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.
- cmp
An ordering to be used for comparing elements.
- returns
an option value containing the first element of this immutable sequence with the largest value measured by function f with respect to the ordering
cmp
.
- Definition Classes
- IterableOnceOps
- def maxOption[B >: Nothing](implicit ord: math.Ordering[B]): Option[Nothing]
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 immutable sequence with respect to the ordering
ord
.
- Definition Classes
- IterableOnceOps
- def min[B >: Nothing](implicit ord: math.Ordering[B]): Nothing
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 immutable sequence with respect to the ordering
ord
.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this immutable sequence is empty.
- def minBy[B](f: (Nothing) => B)(implicit cmp: math.Ordering[B]): Nothing
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.
- cmp
An ordering to be used for comparing elements.
- returns
the first element of this immutable sequence with the smallest value measured by function f with respect to the ordering
cmp
.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this immutable sequence is empty.
- def minByOption[B](f: (Nothing) => B)(implicit cmp: math.Ordering[B]): Option[Nothing]
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.
- cmp
An ordering to be used for comparing elements.
- returns
an option value containing the first element of this immutable sequence with the smallest value measured by function f with respect to the ordering
cmp
.
- Definition Classes
- IterableOnceOps
- def minOption[B >: Nothing](implicit ord: math.Ordering[B]): Option[Nothing]
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 immutable sequence with respect to the ordering
ord
.
- Definition Classes
- IterableOnceOps
- final def mkString: String
Displays all elements of this immutable sequence in a string.
Displays all elements of this immutable sequence in a string.
Delegates to addString, which can be overridden.
- returns
a string representation of this immutable sequence. In the resulting string the string representations (w.r.t. the method
toString
) of all elements of this immutable sequence follow each other without any separator string.
- Definition Classes
- IterableOnceOps
- Annotations
- @inline()
- final def mkString(sep: String): String
Displays all elements of this immutable sequence in a string using a separator string.
Displays all elements of this immutable sequence in a string using a separator string.
Delegates to addString, which can be overridden.
- sep
the separator string.
- returns
a string representation of this immutable sequence. In the resulting string the string representations (w.r.t. the method
toString
) of all elements of this immutable sequence 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 immutable sequence in a string using start, end, and separator strings.
Displays all elements of this immutable sequence 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 immutable sequence. 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 immutable sequence are separated by the stringsep
.
- Definition Classes
- IterableOnceOps
List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
Example: - final def ne(arg0: AnyRef): Boolean
Equivalent to
!(this eq that)
.Equivalent to
!(this eq that)
.- returns
true
if the argument is not a reference to the receiver object;false
otherwise.
- Definition Classes
- AnyRef
- def newSpecificBuilder: Builder[Nothing, Stream[Nothing]]
- 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
- Definition Classes
- IterableFactoryDefaults → IterableOps
- Note
When implementing a custom collection type and refining
,C
to the new type, this method needs to be overridden (the compiler will issue an error otherwise). In the common case 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.
- def nonEmpty: Boolean
Tests whether the immutable sequence is not empty.
Tests whether the immutable sequence is not empty.
- returns
true
if the immutable sequence contains at least one element,false
otherwise.
- Definition Classes
- IterableOnceOps
- Annotations
- @deprecatedOverriding()
- final def notify(): Unit
Wakes up a single thread that is waiting on the receiver object's monitor.
Wakes up a single thread that is waiting on the receiver object's monitor.
- Definition Classes
- AnyRef
- Annotations
- @native()
- Note
not specified by SLS as a member of AnyRef
- final def notifyAll(): Unit
Wakes up all threads that are waiting on the receiver object's monitor.
Wakes up all threads that are waiting on the receiver object's monitor.
- Definition Classes
- AnyRef
- Annotations
- @native()
- Note
not specified by SLS as a member of AnyRef
- def occCounts[B](sq: collection.Seq[B]): mutable.Map[B, Int]
- Attributes
- protected[collection]
- Definition Classes
- SeqOps
- def orElse[A1 <: Int, B1 >: Nothing](that: PartialFunction[A1, B1]): PartialFunction[A1, B1]
Composes this partial function with a fallback partial function which gets applied where this partial function is not defined.
Composes this partial function with a fallback partial function which gets applied where this partial function is not defined.
- A1
the argument type of the fallback function
- B1
the result type of the fallback function
- that
the fallback function
- returns
a partial function which has as domain the union of the domains of this partial function and
that
. The resulting partial function takesx
tothis(x)
wherethis
is defined, and tothat(x)
where it is not.
- Definition Classes
- PartialFunction
- def padTo[B >: Nothing](len: Int, elem: B): Stream[B]
A copy of this immutable sequence with an element value appended until a given target length is reached.
A copy of this immutable sequence with an element value appended until a given target length is reached.
- B
the element type of the returned immutable sequence.
- len
the target length
- elem
the padding value
- returns
a new immutable sequence consisting of all elements of this immutable sequence followed by the minimal number of occurrences of
elem
so that the resulting collection has a length of at leastlen
.
- Definition Classes
- SeqOps
- def partition(p: (Nothing) => Boolean): (Stream[Nothing], Stream[Nothing])
A pair of, first, all elements that satisfy predicate
p
and, second, all elements that do not.A pair of, first, all elements that satisfy predicate
p
and, second, all elements that do not. Interesting because it splits a collection in two.The default implementation provided here needs to traverse the collection twice. Strict collections have an overridden version of
partition
inStrictOptimizedIterableOps
, which requires only a single traversal.- Definition Classes
- Stream → IterableOps
- def partitionMap[A1, A2](f: (Nothing) => Either[A1, A2]): (Stream[A1], Stream[A2])
Applies a function
f
to each element of the immutable sequence and returns a pair of immutable sequences: 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 immutable sequence and returns a pair of immutable sequences: 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 = `immutable.Seq`(1, "one", 2, "two", 3, "three") partitionMap { case i: Int => Left(i) case s: String => Right(s) } // xs == (`immutable.Seq`(1, 2, 3), // `immutable.Seq`(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 immutable sequence to an scala.util.Either
- returns
a pair of immutable sequences: the first one made of those values returned by
f
that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.
- Definition Classes
- IterableOps
- def patch[B >: Nothing](from: Int, other: IterableOnce[B], replaced: Int): Stream[B]
Produces a new immutable sequence where a slice of elements in this immutable sequence is replaced by another sequence.
Produces a new immutable sequence where a slice of elements in this immutable sequence is replaced by another sequence.
Patching at negative indices is the same as patching starting at 0. Patching at indices at or larger than the length of the original immutable sequence appends the patch to the end. If more values are replaced than actually exist, the excess is ignored.
- B
the element type of the returned immutable sequence.
- from
the index of the first replaced element
- other
the replacement sequence
- replaced
the number of elements to drop in the original immutable sequence
- returns
a new immutable sequence consisting of all elements of this immutable sequence except that
replaced
elements starting fromfrom
are replaced by all the elements ofother
.
- Definition Classes
- SeqOps
- def permutations: Iterator[Stream[Nothing]]
Iterates over distinct permutations of elements.
Iterates over distinct permutations of elements.
Note: Even when applied to a view or a lazy collection it will always force the elements.
- returns
An Iterator which traverses the distinct permutations of this immutable sequence.
- Definition Classes
- SeqOps
Seq('a', 'b', 'b').permutations.foreach(println) // List(a, b, b) // List(b, a, b) // List(b, b, a)
Example: - final def prepended[B >: Nothing](elem: B): Stream[B]
A copy of the immutable sequence with an element prepended.
A copy of the immutable sequence with an element prepended.
Also, the original immutable sequence is not modified, so you will want to capture the result.
Example:
scala> val x = List(1) x: List[Int] = List(1) scala> val y = 2 +: x y: List[Int] = List(2, 1) scala> println(x) List(1)
- B
the element type of the returned immutable sequence.
- elem
the prepended element
- returns
a new immutable sequence consisting of
value
followed by all elements of this immutable sequence.
- def prependedAll[B >: Nothing](prefix: IterableOnce[B]): Stream[B]
As with
:++
, returns a new collection containing the elements from the left operand followed by the elements from the right operand.As with
:++
, returns a new collection containing the elements from the left operand followed by the elements from the right operand.It differs from
:++
in that the right operand determines the type of the resulting collection rather than the left one. Mnemonic: the COLon is on the side of the new COLlection type.- B
the element type of the returned collection.
- prefix
the iterable to prepend.
- returns
a new immutable sequence which contains all elements of
prefix
followed by all the elements of this immutable sequence.
- Definition Classes
- SeqOps
- def product[B >: Nothing](implicit num: math.Numeric[B]): B
Multiplies up the elements of this collection.
Multiplies up the elements of this collection.
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 immutable sequence with respect to the
*
operator innum
.
- Definition Classes
- IterableOnceOps
- def reduce[B >: Nothing](op: (B, B) => B): B
Reduces the elements of this immutable sequence using the specified associative binary operator.
Reduces the elements of this immutable sequence using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
- B
A type parameter for the binary operator, a supertype of
A
.- op
A binary operator that must be associative.
- returns
The result of applying reduce operator
op
between all the elements if the immutable sequence is nonempty.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this immutable sequence is empty.
- final def reduceLeft[B >: Nothing](f: (B, Nothing) => B): B
Stream specialization of reduceLeft which allows GC to collect along the way.
Stream specialization of reduceLeft which allows GC to collect along the way.
- B
The type of value being accumulated.
- f
The operation to perform on successive elements of the
Stream
.- returns
The accumulated value from successive applications of
f
.
- Definition Classes
- Stream → IterableOnceOps
- def reduceLeftOption[B >: Nothing](op: (B, Nothing) => B): Option[B]
Optionally applies a binary operator to all elements of this immutable sequence, going left to right.
Optionally applies a binary operator to all elements of this immutable sequence, going left to right.
Note: will not terminate for infinite-sized collections.
- B
the result type of the binary operator.
- op
the binary operator.
- returns
an option value containing the result of
reduceLeft(op)
if this immutable sequence is nonempty,None
otherwise.
- Definition Classes
- IterableOnceOps
- def reduceOption[B >: Nothing](op: (B, B) => B): Option[B]
Reduces the elements of this immutable sequence, if any, using the specified associative binary operator.
Reduces the elements of this immutable sequence, if any, using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
- B
A type parameter for the binary operator, a supertype of
A
.- op
A binary operator that must be associative.
- returns
An option value containing result of applying reduce operator
op
between all the elements if the collection is nonempty, andNone
otherwise.
- Definition Classes
- IterableOnceOps
- def reduceRight[B >: Nothing](op: (Nothing, B) => B): B
Applies a binary operator to all elements of this immutable sequence, going right to left.
Applies a binary operator to all elements of this immutable sequence, going right to left.
Note: will not terminate for infinite-sized collections.
- B
the result type of the binary operator.
- op
the binary operator.
- returns
the result of inserting
op
between consecutive elements of this immutable sequence, going right to left:op(x1, op(x2, ..., op(xn-1, xn)...))
wherex1, ..., xn
are the elements of this immutable sequence.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this immutable sequence is empty.
- def reduceRightOption[B >: Nothing](op: (Nothing, B) => B): Option[B]
Optionally applies a binary operator to all elements of this immutable sequence, going right to left.
Optionally applies a binary operator to all elements of this immutable sequence, going right to left.
Note: will not terminate for infinite-sized collections.
- B
the result type of the binary operator.
- op
the binary operator.
- returns
an option value containing the result of
reduceRight(op)
if this immutable sequence is nonempty,None
otherwise.
- Definition Classes
- IterableOnceOps
- def reverse: Stream[Nothing]
Returns new immutable sequence with elements in reversed order.
Returns new immutable sequence with elements in reversed order.
Note: will not terminate for infinite-sized collections.
Note: Even when applied to a view or a lazy collection it will always force the elements.
- returns
A new immutable sequence with all elements of this immutable sequence in reversed order.
- Definition Classes
- SeqOps
- def reverseIterator: Iterator[Nothing]
An iterator yielding elements in reversed order.
An iterator yielding elements in reversed order.
Note: will not terminate for infinite-sized collections.
Note:
xs.reverseIterator
is the same asxs.reverse.iterator
but might be more efficient.- returns
an iterator yielding the elements of this immutable sequence in reversed order
- Definition Classes
- SeqOps
- def reversed: collection.Iterable[Nothing]
- Attributes
- protected
- Definition Classes
- IterableOnceOps
- def runWith[U](action: (Nothing) => U): (Int) => Boolean
Composes this partial function with an action function which gets applied to results of this partial function.
Composes this partial function with an action function which gets applied to results of this partial function. The action function is invoked only for its side effects; its result is ignored.
Note that expression
pf.runWith(action)(x)
is equivalent toif(pf isDefinedAt x) { action(pf(x)); true } else false
except that
runWith
is implemented viaapplyOrElse
and thus potentially more efficient. UsingrunWith
avoids double evaluation of pattern matchers and guards for partial function literals.- action
the action function
- returns
a function which maps arguments
x
toisDefinedAt(x)
. The resulting function runsaction(this(x))
wherethis
is defined.
- Definition Classes
- PartialFunction
- See also
applyOrElse
.
- def sameElements[B >: Nothing](that: IterableOnce[B]): Boolean
Are the elements of this collection the same (and in the same order) as those of
that
?Are the elements of this collection the same (and in the same order) as those of
that
?- Definition Classes
- LinearSeqOps → SeqOps
- def scan[B >: Nothing](z: B)(op: (B, B) => B): Stream[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 immutable sequence containing the prefix scan of the elements in this immutable sequence
- Definition Classes
- IterableOps
- def scanLeft[B](z: B)(op: (B, Nothing) => B): Stream[B]
Produces a immutable sequence containing cumulative results of applying the operator going left to right, including the initial value.
Produces a immutable sequence containing cumulative results of applying the operator going left to right, including the initial value.
Note: will not terminate for infinite-sized collections.
- 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
- Stream → IterableOps → IterableOnceOps
- def scanRight[B](z: B)(op: (Nothing, B) => B): Stream[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: Even when applied to a view or a lazy collection it will always force the elements.
Example:
List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)
- B
the type of the elements in the resulting collection
- z
the initial value
- op
the binary operator applied to the intermediate result and the element
- returns
collection with intermediate results
- Definition Classes
- IterableOps
- def search[B >: Nothing](elem: B, from: Int, to: Int)(implicit ord: Ordering[B]): SearchResult
Search within an interval in this sorted sequence for a specific element.
Search within an interval in this sorted sequence for a specific element. If this sequence is an
IndexedSeq
, a binary search is used. Otherwise, a linear search is used.The sequence should be sorted with the same
Ordering
before calling; otherwise, the results are undefined.- elem
the element to find.
- from
the index where the search starts.
- to
the index following where the search ends.
- ord
the ordering to be used to compare elements.
- returns
a
Found
value containing the index corresponding to the element in the sequence, or theInsertionPoint
where the element would be inserted if the element is not in the sequence.
- Definition Classes
- SeqOps
- Note
if
to <= from
, the search space is empty, and anInsertionPoint
atfrom
is returned- See also
scala.collection.SeqOps, method
sorted
- def search[B >: Nothing](elem: B)(implicit ord: Ordering[B]): SearchResult
Search this sorted sequence for a specific element.
Search this sorted sequence for a specific element. If the sequence is an
IndexedSeq
, a binary search is used. Otherwise, a linear search is used.The sequence should be sorted with the same
Ordering
before calling; otherwise, the results are undefined.- elem
the element to find.
- ord
the ordering to be used to compare elements.
- returns
a
Found
value containing the index corresponding to the element in the sequence, or theInsertionPoint
where the element would be inserted if the element is not in the sequence.
- Definition Classes
- SeqOps
- See also
scala.collection.SeqOps, method
sorted
- def segmentLength(p: (Nothing) => Boolean, from: Int): Int
Computes the length of the longest segment that starts from some index and whose elements all satisfy some predicate.
Computes the length of the longest segment that starts from some index and whose elements all satisfy some predicate.
Note: may not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- from
the index where the search starts.
- returns
the length of the longest segment of this immutable sequence starting from index
from
such that every element of the segment satisfies the predicatep
.
- Definition Classes
- LinearSeqOps → SeqOps
- final def segmentLength(p: (Nothing) => Boolean): Int
Computes the length of the longest segment that starts from the first element and whose elements all satisfy some predicate.
Computes the length of the longest segment that starts from the first element and whose elements all satisfy some predicate.
Note: may not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
the length of the longest segment of this immutable sequence that starts from the first element such that every element of the segment satisfies the predicate
p
.
- Definition Classes
- SeqOps
- final def size: Int
The size of this immutable sequence.
The size of this immutable sequence.
Note: will not terminate for infinite-sized collections.
- returns
the number of elements in this immutable sequence.
- Definition Classes
- SeqOps → IterableOnceOps
- final def sizeCompare(that: collection.Iterable[_]): Int
Compares the size of this immutable sequence to the size of another
Iterable
.Compares the size of this immutable sequence to the size of another
Iterable
.- that
the
Iterable
whose size is compared with this immutable sequence'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
.
- Definition Classes
- SeqOps → IterableOps
- final def sizeCompare(otherSize: Int): Int
Compares the size of this immutable sequence to a test value.
Compares the size of this immutable sequence 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
.
- Definition Classes
- SeqOps → IterableOps
- See also
- final def sizeIs: SizeCompareOps
Returns a value class containing operations for comparing the size of this immutable sequence to a test value.
Returns a value class containing operations for comparing the size of this immutable sequence to a test value.
These operations are implemented in terms of
sizeCompare(Int)
, and allow the following more readable usages:this.sizeIs < size // this.sizeCompare(size) < 0 this.sizeIs <= size // this.sizeCompare(size) <= 0 this.sizeIs == size // this.sizeCompare(size) == 0 this.sizeIs != size // this.sizeCompare(size) != 0 this.sizeIs >= size // this.sizeCompare(size) >= 0 this.sizeIs > size // this.sizeCompare(size) > 0
- Definition Classes
- IterableOps
- Annotations
- @inline()
- def slice(from: Int, until: Int): Stream[Nothing]
Selects an interval of elements.
Selects an interval of elements. The returned immutable sequence is made up of all elements
x
which satisfy the invariant:from <= indexOf(x) < until
- from
the lowest index to include from this immutable sequence.
- until
the lowest index to EXCLUDE from this immutable sequence.
- returns
a immutable sequence containing the elements greater than or equal to index
from
extending up to (but not including) indexuntil
of this immutable sequence.
- Definition Classes
- IterableOps → IterableOnceOps
- def sliding(size: Int, step: Int): Iterator[Stream[Nothing]]
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 immutable sequences 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.
- Definition Classes
- IterableOps
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[Stream[Nothing]]
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 immutable sequences 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.
- Definition Classes
- IterableOps
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 sortBy[B](f: (Nothing) => B)(implicit ord: Ordering[B]): Stream[Nothing]
Sorts this immutable sequence according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.
Sorts this immutable sequence according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.
Note: will not terminate for infinite-sized collections.
Note: Even when applied to a view or a lazy collection it will always force the elements.
The sort is stable. That is, elements that are equal (as determined by
ord.compare
) appear in the same order in the sorted sequence as in the original.- B
the target type of the transformation
f
, and the type where the orderingord
is defined.- f
the transformation function mapping elements to some other domain
B
.- ord
the ordering assumed on domain
B
.- returns
a immutable sequence consisting of the elements of this immutable sequence sorted according to the ordering where
x < y
iford.lt(f(x), f(y))
.
- Definition Classes
- SeqOps
val words = "The quick brown fox jumped over the lazy dog".split(' ') // this works because scala.Ordering will implicitly provide an Ordering[Tuple2[Int, Char]] words.sortBy(x => (x.length, x.head)) res0: Array[String] = Array(The, dog, fox, the, lazy, over, brown, quick, jumped)
- See also
Example: - def sortWith(lt: (Nothing, Nothing) => Boolean): Stream[Nothing]
Sorts this immutable sequence according to a comparison function.
Sorts this immutable sequence according to a comparison function.
Note: will not terminate for infinite-sized collections.
Note: Even when applied to a view or a lazy collection it will always force the elements.
The sort is stable. That is, elements that are equal (as determined by
lt
) appear in the same order in the sorted sequence as in the original.- lt
the comparison function which tests whether its first argument precedes its second argument in the desired ordering.
- returns
a immutable sequence consisting of the elements of this immutable sequence sorted according to the comparison function
lt
.
- Definition Classes
- SeqOps
List("Steve", "Tom", "John", "Bob").sortWith(_.compareTo(_) < 0) = List("Bob", "John", "Steve", "Tom")
Example: - def sorted[B >: Nothing](implicit ord: Ordering[B]): Stream[Nothing]
Sorts this immutable sequence according to an Ordering.
Sorts this immutable sequence according to an Ordering.
The sort is stable. That is, elements that are equal (as determined by
ord.compare
) appear in the same order in the sorted sequence as in the original.- ord
the ordering to be used to compare elements.
- returns
a immutable sequence consisting of the elements of this immutable sequence sorted according to the ordering
ord
.
- Definition Classes
- SeqOps
- See also
scala.math.Ordering Note: Even when applied to a view or a lazy collection it will always force the elements.
- def span(p: (Nothing) => Boolean): (Stream[Nothing], Stream[Nothing])
Splits this immutable sequence into a prefix/suffix pair according to a predicate.
Splits this immutable sequence 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.- p
the test predicate
- returns
a pair consisting of the longest prefix of this immutable sequence whose elements all satisfy
p
, and the rest of this immutable sequence.
- Definition Classes
- IterableOps → IterableOnceOps
- def splitAt(n: Int): (Stream[Nothing], Stream[Nothing])
Splits this immutable sequence into a prefix/suffix pair at a given position.
Splits this immutable sequence into a prefix/suffix pair at a given position.
Note:
c splitAt n
is equivalent to (but possibly more efficient than)(c take n, c drop n)
.- n
the position at which to split.
- returns
a pair of immutable sequences consisting of the first
n
elements of this immutable sequence, and the other elements.
- Definition Classes
- IterableOps → IterableOnceOps
- def startsWith[B >: Nothing](that: IterableOnce[B], offset: Int = 0): Boolean
Tests whether this immutable sequence contains the given sequence at a given index.
Tests whether this immutable sequence contains the given sequence at a given index.
Note: If the both the receiver object
this
and the argumentthat
are infinite sequences this method may not terminate.- that
the sequence to test
- offset
the index where the sequence is searched.
- returns
true
if the sequencethat
is contained in this immutable sequence at indexoffset
, otherwisefalse
.
- Definition Classes
- SeqOps
- def stepper[S <: Stepper[_]](implicit shape: StepperShape[Nothing, 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 stringPrefix: String
- def sum[B >: Nothing](implicit num: math.Numeric[B]): B
Sums up the elements of this collection.
Sums up the elements of this collection.
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 immutable sequence with respect to the
+
operator innum
.
- Definition Classes
- IterableOnceOps
- final def synchronized[T0](arg0: => T0): T0
Executes the code in
body
with an exclusive lock onthis
.Executes the code in
body
with an exclusive lock onthis
.- returns
the result of
body
- Definition Classes
- AnyRef
- def tail: Stream[Nothing]
<invalid inheritdoc annotation>
<invalid inheritdoc annotation>
Note: *Must* be overridden in subclasses. The default implementation is inherited from IterableOps.
- Definition Classes
- Empty → Stream → LinearSeqOps → IterableOps
- def tailDefined: Boolean
- def tails: Iterator[Stream[Nothing]]
Iterates over the tails of this immutable sequence.
Iterates over the tails of this immutable sequence. The first value will be this immutable sequence and the final one will be an empty immutable sequence, with the intervening values the results of successive applications of
tail
.- returns
an iterator over all the tails of this immutable sequence
- Definition Classes
- LinearSeqOps → IterableOps
List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)
Example: - def take(n: Int): Stream[Nothing]
Selects the first n elements.
Selects the first n elements.
- n
the number of elements to take from this immutable sequence.
- returns
a immutable sequence consisting only of the first
n
elements of this immutable sequence, or else the whole immutable sequence, if it has less thann
elements. Ifn
is negative, returns an empty immutable sequence.
- Definition Classes
- Stream → IterableOps → IterableOnceOps
- def takeRight(n: Int): Stream[Nothing]
Selects the last n elements.
Selects the last n elements.
- n
the number of elements to take from this immutable sequence.
- returns
a immutable sequence consisting only of the last
n
elements of this immutable sequence, or else the whole immutable sequence, if it has less thann
elements. Ifn
is negative, returns an empty immutable sequence.
- Definition Classes
- IterableOps
- def takeWhile(p: (Nothing) => Boolean): Stream[Nothing]
Takes longest prefix of elements that satisfy a predicate.
Takes longest prefix of elements that satisfy a predicate.
- p
The predicate used to test elements.
- returns
the longest prefix of this immutable sequence whose elements all satisfy the predicate
p
.
- Definition Classes
- IterableOps → IterableOnceOps
- def tapEach[U](f: (Nothing) => U): Stream[Nothing]
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 immutable sequence
- returns
The same logical collection as this
- Definition Classes
- IterableOps → IterableOnceOps
- def to[C1](factory: Factory[Nothing, C1]): C1
Given a collection factory
factory
, convert this collection to the appropriate representation for the current element typeA
.Given a collection factory
factory
, convert this 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 >: Nothing](implicit arg0: ClassTag[B]): Array[B]
Convert collection to array.
Convert collection to array.
Implementation note: DO NOT call Array.from from this method.
- Definition Classes
- IterableOnceOps
- final def toBuffer[B >: Nothing]: Buffer[B]
- Definition Classes
- IterableOnceOps
- Annotations
- @inline()
- def toIndexedSeq: IndexedSeq[Nothing]
- Definition Classes
- IterableOnceOps
- def toList: List[Nothing]
- Definition Classes
- IterableOnceOps
- def toMap[K, V](implicit ev: <:<[Nothing, (K, V)]): Map[K, V]
- Definition Classes
- IterableOnceOps
- final def toSeq: Empty.this.type
- returns
This collection as a
Seq[A]
. This is equivalent toto(Seq)
but might be faster.
- Definition Classes
- Seq → IterableOnceOps
- def toSet[B >: Nothing]: Set[B]
- Definition Classes
- IterableOnceOps
- def toString(): String
- returns
a string representation of this collection. Undefined elements are represented with
"_"
, an undefined tail is represented with"<not computed>"
, and cycles are represented with"<cycle>"
Examples:"Stream(_, <not computed>)"
, a non-empty stream, whose head has not been evaluated ;"Stream(_, 1, _, <not computed>)"
, a stream with at least three elements, the second one has been evaluated ;"Stream(1, 2, 3, <cycle>)"
, an infinite stream that contains a cycle at the fourth element.
- def toVector: Vector[Nothing]
- Definition Classes
- IterableOnceOps
- def transpose[B](implicit asIterable: (Nothing) => collection.Iterable[B]): Stream[Stream[B]]
Transposes this immutable sequence of iterable collections into a immutable sequence of immutable sequences.
Transposes this immutable sequence of iterable collections into a immutable sequence of immutable sequences.
The resulting collection's type will be guided by the static type of immutable sequence. 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 immutable sequence is an
Iterable
.- returns
a two-dimensional immutable sequence of immutable sequences which has as nth row the nth column of this immutable sequence.
- Definition Classes
- IterableOps
- Exceptions thrown
IllegalArgumentException
if all collections in this immutable sequence are not of the same size.
- def unapply(a: Int): Option[Nothing]
Tries to extract a
B
from anA
in a pattern matching expression.Tries to extract a
B
from anA
in a pattern matching expression.- Definition Classes
- PartialFunction
- def unzip[A1, A2](implicit asPair: (Nothing) => (A1, A2)): (Stream[A1], Stream[A2])
Converts this immutable sequence of pairs into two collections of the first and second half of each pair.
Converts this immutable sequence of pairs into two collections of the first and second half of each pair.
val xs = `immutable.Seq`( (1, "one"), (2, "two"), (3, "three")).unzip // xs == (`immutable.Seq`(1, 2, 3), // `immutable.Seq`(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 immutable sequence is a pair.
- returns
a pair of immutable sequences, containing the first, respectively second half of each element pair of this immutable sequence.
- Definition Classes
- IterableOps
- def unzip3[A1, A2, A3](implicit asTriple: (Nothing) => (A1, A2, A3)): (Stream[A1], Stream[A2], Stream[A3])
Converts this immutable sequence of triples into three collections of the first, second, and third element of each triple.
Converts this immutable sequence of triples into three collections of the first, second, and third element of each triple.
val xs = `immutable.Seq`( (1, "one", '1'), (2, "two", '2'), (3, "three", '3')).unzip3 // xs == (`immutable.Seq`(1, 2, 3), // `immutable.Seq`(one, two, three), // `immutable.Seq`(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 immutable sequence is a triple.
- returns
a triple of immutable sequences, containing the first, second, respectively third member of each element triple of this immutable sequence.
- Definition Classes
- IterableOps
- def updated[B >: Nothing](index: Int, elem: B): Stream[B]
A copy of this immutable sequence with one single replaced element.
A copy of this immutable sequence with one single replaced element.
- B
the element type of the returned immutable sequence.
- index
the position of the replacement
- elem
the replacing element
- returns
a new immutable sequence which is a copy of this immutable sequence with the element at position
index
replaced byelem
.
- Definition Classes
- SeqOps
- Exceptions thrown
IndexOutOfBoundsException
ifindex
does not satisfy0 <= index < length
. In case of a lazy collection this exception may be thrown at a later time or not at all (if the end of the collection is never evaluated).
- def view: SeqView[Nothing]
A view over the elements of this collection.
A view over the elements of this collection.
- Definition Classes
- SeqOps → IterableOps
- final def wait(): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.
- Definition Classes
- AnyRef
- Annotations
- @throws(classOf[java.lang.InterruptedException])
- Note
not specified by SLS as a member of AnyRef
- final def wait(arg0: Long, arg1: Int): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-
- Definition Classes
- AnyRef
- Annotations
- @throws(classOf[java.lang.InterruptedException])
- Note
not specified by SLS as a member of AnyRef
- final def wait(arg0: Long): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.
- final def withFilter(p: (Nothing) => Boolean): collection.WithFilter[Nothing, Stream]
A
collection.WithFilter
which allows GC of the head of stream during processingA
collection.WithFilter
which allows GC of the head of stream during processing- 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 immutable sequence which satisfy the predicatep
.
- Definition Classes
- Stream → IterableOps
- def writeReplace(): AnyRef
- Attributes
- protected[this]
- Definition Classes
- Stream
- final def zip[B](that: IterableOnce[B]): Stream[(Nothing, B)]
Returns a immutable sequence formed from this immutable sequence and another iterable collection by combining corresponding elements in pairs.
Returns a immutable sequence formed from this immutable sequence 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 immutable sequence containing pairs consisting of corresponding elements of this immutable sequence and
that
. The length of the returned collection is the minimum of the lengths of this immutable sequence andthat
.
- Definition Classes
- Stream → IterableOps
- def zipAll[A1 >: Nothing, B](that: collection.Iterable[B], thisElem: A1, thatElem: B): Stream[(A1, B)]
Returns a immutable sequence formed from this immutable sequence and another iterable collection by combining corresponding elements in pairs.
Returns a immutable sequence formed from this immutable sequence 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 immutable sequence is shorter than
that
.- thatElem
the element to be used to fill up the result if
that
is shorter than this immutable sequence.- returns
a new collection of type
That
containing pairs consisting of corresponding elements of this immutable sequence andthat
. The length of the returned collection is the maximum of the lengths of this immutable sequence andthat
. If this immutable sequence is shorter thanthat
,thisElem
values are used to pad the result. Ifthat
is shorter than this immutable sequence,thatElem
values are used to pad the result.
- Definition Classes
- IterableOps
- final def zipWithIndex: Stream[(Nothing, Int)]
Zips this immutable sequence with its indices.
Zips this immutable sequence with its indices.
- returns
A new immutable sequence containing pairs consisting of all elements of this immutable sequence paired with their index. Indices start at
0
.
- Definition Classes
- Stream → IterableOps → IterableOnceOps
List("a", "b", "c").zipWithIndex == List(("a", 0), ("b", 1), ("c", 2))
Example:
Deprecated Value Members
- final def /:[B](z: B)(op: (B, Nothing) => B): B
- Definition Classes
- IterableOnceOps
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use foldLeft instead of /:
- final def :\[B](z: B)(op: (Nothing, 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, Nothing) => B, combop: (B, B) => B): B
- Definition Classes
- IterableOnceOps
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0)
aggregate
is not relevant for sequential collections. UsefoldLeft(z)(seqop)
instead.
- final def append[B >: Nothing](rest: => IterableOnce[B]): Stream[B]
The stream resulting from the concatenation of this stream with the argument stream.
The stream resulting from the concatenation of this stream with the argument stream.
- rest
The collection that gets appended to this stream
- returns
The stream containing elements of this stream and the iterable object.
- Definition Classes
- Stream
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) The
append
operation has been renamedlazyAppendedAll
- def companion: IterableFactory[[_]Stream[_]]
- Definition Classes
- IterableOps
- Annotations
- @deprecated @deprecatedOverriding() @inline()
- Deprecated
(Since version 2.13.0) Use iterableFactory instead
- final def copyToBuffer[B >: Nothing](dest: Buffer[B]): Unit
- Definition Classes
- IterableOnceOps
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use
dest ++= coll
instead
- def hasDefiniteSize: Boolean
Tests whether this immutable sequence is known to have a finite size.
Tests whether this immutable sequence 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
- Stream → 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
- final def prefixLength(p: (Nothing) => Boolean): Int
Returns the length of the longest prefix whose elements all satisfy some predicate.
Returns the length of the longest prefix whose elements all satisfy some predicate.
Note: may not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
the length of the longest prefix of this immutable sequence such that every element of the segment satisfies the predicate
p
.
- Definition Classes
- SeqOps
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use segmentLength instead of prefixLength
- def print(sep: String): Unit
Prints elements of this stream one by one, separated by
sep
.Prints elements of this stream one by one, separated by
sep
.- sep
The separator string printed between consecutive elements.
- Definition Classes
- Stream
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use print(stream.force.mkString(sep)) instead
- def print(): Unit
Prints elements of this stream one by one, separated by commas.
Prints elements of this stream one by one, separated by commas.
- Definition Classes
- Stream
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use print(stream.force.mkString(", ")) instead
- final def repr: Stream[Nothing]
- Definition Classes
- IterableOps
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use coll instead of repr in a collection implementation, use the collection value itself from the outside
- def reverseMap[B](f: (Nothing) => B): Stream[B]
- Definition Classes
- SeqOps
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .reverseIterator.map(f).to(...) instead of .reverseMap(f)
- def seq: Empty.this.type
- Definition Classes
- Iterable
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Iterable.seq always returns the iterable itself
- final def toIterable: Empty.this.type
- returns
This collection as an
Iterable[A]
. No new collection will be built ifthis
is already anIterable[A]
.
- Definition Classes
- Iterable → IterableOps
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.7) toIterable is internal and will be made protected; its name is similar to
toList
ortoSeq
, but it doesn't copy non-immutable collections
- final def toIterator: Iterator[Nothing]
- Definition Classes
- IterableOnceOps
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use .iterator instead of .toIterator
- final def toStream: Stream[Nothing]
- Definition Classes
- IterableOnceOps
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use .to(LazyList) instead of .toStream
- final def toTraversable: collection.Traversable[Nothing]
Converts this immutable sequence to an unspecified Iterable.
Converts this immutable sequence to an unspecified Iterable. Will return the same collection if this instance is already Iterable.
- returns
An Iterable containing all elements of this immutable sequence.
- Definition Classes
- IterableOps
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) toTraversable is internal and will be made protected; its name is similar to
toList
ortoSeq
, but it doesn't copy non-immutable collections
- final def union[B >: Nothing](that: collection.Seq[B]): Stream[B]
Produces a new sequence which contains all elements of this immutable sequence and also all elements of a given sequence.
Produces a new sequence which contains all elements of this immutable sequence and also all elements of a given sequence.
xs union ys
is equivalent toxs ++ ys
.- B
the element type of the returned immutable sequence.
- that
the sequence to add.
- returns
a new collection which contains all elements of this immutable sequence followed by all elements of
that
.
- Definition Classes
- SeqOps
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use
concat
instead
- def view(from: Int, until: Int): View[Nothing]
A view over a slice of the elements of this collection.
A view over a slice of the elements of this collection.
- Definition Classes
- IterableOps
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use .view.slice(from, until) instead of .view(from, until)
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
.