sealed abstract class Option[+A] extends Product with Serializable
Represents optional values. Instances of Option
are either an instance of scala.Some or the object None
.
The most idiomatic way to use an scala.Option instance is to treat it
as a collection or monad and use map
,flatMap
, filter
, or
foreach
:
val name: Option[String] = request getParameter "name" val upper = name map { _.trim } filter { _.length != 0 } map { _.toUpperCase } println(upper getOrElse "")
Note that this is equivalent to
val upper = for { name <- request getParameter "name" trimmed <- Some(name.trim) upper <- Some(trimmed.toUpperCase) if trimmed.length != 0 } yield upper println(upper getOrElse "")
Because of how for comprehension works, if None
is returned
from request.getParameter
, the entire expression results in
None
This allows for sophisticated chaining of scala.Option values without having to check for the existence of a value.
A less-idiomatic way to use scala.Option values is via pattern matching:
val nameMaybe = request getParameter "name" nameMaybe match { case Some(name) => println(name.trim.toUppercase) case None => println("No name value") }
- Self Type
- Option[A]
- Annotations
- @SerialVersionUID()
- Source
- Option.scala
- Version
1.1, 16/01/2007
- Note
Many of the methods in here are duplicative with those in the Traversable hierarchy, but they are duplicated for a reason: the implicit conversion tends to leave one with an Iterable in situations where one could have retained an Option.
- Alphabetic
- By Inheritance
- Option
- Serializable
- Serializable
- Product
- Equals
- AnyRef
- Any
- by option2Iterable
- by any2stringadd
- by StringFormat
- by Ensuring
- by ArrowAssoc
- Hide All
- Show All
- Public
- All
Type Members
-
class
WithFilter extends AnyRef
We need a whole WithFilter class to honor the "doesn't create a new collection" contract even though it seems unlikely to matter much in a collection with max size 1.
Abstract Value Members
-
abstract
def
canEqual(that: Any): Boolean
A method that should be called from every well-designed equals method that is open to be overridden in a subclass.
A method that should be called from every well-designed equals method that is open to be overridden in a subclass. See Programming in Scala, Chapter 28 for discussion and design.
- that
the value being probed for possible equality
- returns
true if this instance can possibly equal
that
, otherwise false
- Definition Classes
- Equals
-
abstract
def
get: A
Returns the option's value.
Returns the option's value.
- Exceptions thrown
java.util.NoSuchElementException
if the option is empty.- Note
The option must be nonempty.
-
abstract
def
isEmpty: Boolean
Returns true if the option is
None
, false otherwise. -
abstract
def
productArity: Int
The size of this product.
-
abstract
def
productElement(n: Int): Any
The nth element of this product, 0-based.
The nth element of this product, 0-based. In other words, for a product
A(x1, ..., xk)
, returnsx(n+1)
where0 <= n < k
.- n
the index of the element to return
- returns
the element
n
elements after the first element
- Definition Classes
- Product
- Exceptions thrown
Concrete Value Members
-
final
def
!=(arg0: Any): Boolean
Test two objects for inequality.
Test two objects for inequality.
- returns
true
if !(this == that), false otherwise.
- Definition Classes
- 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
-
def
+(other: String): String
- Implicit
- This member is added by an implicit conversion from Option[A] to any2stringadd[Option[A]] performed by method any2stringadd in scala.Predef.
- Definition Classes
- any2stringadd
-
final
def
++[B >: A](suffix: collection.Iterable[B]): collection.Iterable[B]
Alias for
concat
Alias for
concat
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
- Annotations
- @inline()
-
def
->[B](y: B): (Option[A], B)
- Implicit
- This member is added by an implicit conversion from Option[A] to ArrowAssoc[Option[A]] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
- Annotations
- @inline()
-
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(b: collection.mutable.StringBuilder): collection.mutable.StringBuilder
Appends all elements of this iterable collection to a string builder.
Appends all elements of this iterable collection to a string builder. The written text consists of the string representations (w.r.t. the method
toString
) of all elements of this iterable collection without any separator string.Example:
scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = new StringBuilder() b: StringBuilder = scala> val h = a.addString(b) h: StringBuilder = 1234
- b
the string builder to which elements are appended.
- returns
the string builder
b
to which elements were appended.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
def
addString(b: collection.mutable.StringBuilder, sep: String): collection.mutable.StringBuilder
Appends all elements of this iterable collection to a string builder using a separator string.
Appends all elements of this iterable collection to a string builder using a separator string. The written text consists of the string representations (w.r.t. the method
toString
) of all elements of this iterable collection, separated by the stringsep
.Example:
scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = new StringBuilder() b: StringBuilder = scala> a.addString(b, ", ") res0: StringBuilder = 1, 2, 3, 4
- b
the string builder to which elements are appended.
- sep
the separator string.
- returns
the string builder
b
to which elements were appended.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
def
addString(b: collection.mutable.StringBuilder, start: String, sep: String, end: String): b.type
Appends all elements of this iterable collection to a string builder using start, end, and separator strings.
Appends all elements of this iterable collection to a string builder using start, end, and separator strings. The written text begins with the string
start
and ends with the stringend
. Inside, the string representations (w.r.t. the methodtoString
) of all elements of this iterable collection are separated by the stringsep
.Example:
scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = new StringBuilder() b: StringBuilder = scala> a.addString(b , "List(" , ", " , ")") res5: StringBuilder = List(1, 2, 3, 4)
- b
the string builder to which elements are appended.
- start
the starting string.
- sep
the separator string.
- end
the ending string.
- returns
the string builder
b
to which elements were appended.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
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
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).It is recommended to overwrite this method even if the default implementation returns the correct name, to avoid the implementation using reflection.
- returns
a string representation which starts the result of
toString
applied to this iterable collection. By default the string prefix is the simple name of the collection class iterable collection.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
def
clone(): AnyRef
Create a copy of the receiver object.
-
final
def
collect[B](pf: PartialFunction[A, B]): Option[B]
Returns a scala.Some containing the result of applying
pf
to this scala.Option's contained value, if this option is nonempty andpf
is defined for that value.Returns a scala.Some containing the result of applying
pf
to this scala.Option's contained value, if this option is nonempty andpf
is defined for that value. ReturnsNone
otherwise.- pf
the partial function.
- returns
the result of applying
pf
to this scala.Option's value (if possible), orNone
.
- Annotations
- @inline()
// Returns Some(HTTP) because the partial function covers the case. Some("http") collect {case "http" => "HTTP"} // Returns None because the partial function doesn't cover the case. Some("ftp") collect {case "http" => "HTTP"} // Returns None because the option is empty. There is no value to pass to the partial function. None collect {case value => value}
Example: -
def
collectFirst[B](pf: PartialFunction[A, B]): Option[B]
Finds the first element of the iterable collection for which the given partial function is defined, and applies the partial function to it.
Finds the first element of the iterable collection for which the given partial function is defined, and applies the partial function to it.
Note: may not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- pf
the partial function
- returns
an option value containing pf applied to the first value for which it is defined, or
None
if none exists.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)
Example: -
def
concat[B >: A](suffix: collection.Iterable[B]): collection.Iterable[B]
Returns a new iterable collection containing the elements from the left hand operand followed by the elements from the right hand operand.
Returns a new iterable collection containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the iterable collection is the most specific superclass encompassing the element types of the two operands.
- B
the element type of the returned collection.
- suffix
the traversable to append.
- returns
a new iterable collection which contains all elements of this iterable collection followed by all elements of
suffix
.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
final
def
contains[A1 >: A](elem: A1): Boolean
Tests whether the option contains a given value as an element.
Tests whether the option contains a given value as an element.
- elem
the element to test.
- returns
true
if the option has an element that is equal (as determined by==
) toelem
,false
otherwise.
// Returns true because Some instance contains string "something" which equals "something". Some("something") contains "something" // Returns false because "something" != "anything". Some("something") contains "anything" // Returns false when method called on None. None contains "anything"
Example: -
def
copyToArray(xs: Array[A], start: Int, len: Int): Unit
[use case]
[use case]- xs
the array to fill.
- start
the starting index.
- len
the maximal number of elements to copy.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
def
copyToArray(xs: Array[A], start: Int): Unit
[use case]
[use case]- xs
the array to fill.
- start
the starting index.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
def
count(p: (A) ⇒ Boolean): Int
Counts the number of elements in the iterable collection which satisfy a predicate.
Counts the number of elements in the iterable collection which satisfy a predicate.
- p
the predicate used to test elements.
- returns
the number of elements satisfying the predicate
p
.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
def
drop(n: Int): collection.Iterable[A]
Selects all elements except first n ones.
Selects all elements except first n ones.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- n
the number of elements to drop from this iterable collection.
- returns
a iterable collection consisting of all elements of this iterable collection except the first
n
ones, or else the empty iterable collection, if this iterable collection has less thann
elements. Ifn
is negative, don't drop any elements.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps → IterableOnceOps
- Note
Reuse: $consumesAndProducesIterator
-
def
dropRight(n: Int): collection.Iterable[A]
The rest of the collection without its
n
last elements.The rest of the collection without its
n
last elements. For linear, immutable collections this should avoid making a copy.- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
def
dropWhile(p: (A) ⇒ Boolean): collection.Iterable[A]
Drops longest prefix of elements that satisfy a predicate.
Drops longest prefix of elements that satisfy a predicate.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- p
The predicate used to test elements.
- returns
the longest suffix of this iterable collection whose first element does not satisfy the predicate
p
.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps → IterableOnceOps
- Note
Reuse: $consumesAndProducesIterator
-
def
ensuring(cond: (Option[A]) ⇒ Boolean, msg: ⇒ Any): Option[A]
- Implicit
- This member is added by an implicit conversion from Option[A] to Ensuring[Option[A]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
def
ensuring(cond: (Option[A]) ⇒ Boolean): Option[A]
- Implicit
- This member is added by an implicit conversion from Option[A] to Ensuring[Option[A]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
def
ensuring(cond: Boolean, msg: ⇒ Any): Option[A]
- Implicit
- This member is added by an implicit conversion from Option[A] to Ensuring[Option[A]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
def
ensuring(cond: Boolean): Option[A]
- Implicit
- This member is added by an implicit conversion from Option[A] to Ensuring[Option[A]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
final
def
eq(arg0: AnyRef): Boolean
Tests whether the argument (
that
) is a reference to the receiver object (this
).Tests whether the argument (
that
) is a reference to the receiver object (this
).The
eq
method implements an equivalence relation on non-null instances 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(arg0: Any): Boolean
The equality method for reference types.
-
final
def
exists(p: (A) ⇒ Boolean): Boolean
Returns true if this option is nonempty and the predicate
p
returns true when applied to this scala.Option's value.Returns true if this option is nonempty and the predicate
p
returns true when applied to this scala.Option's value. Otherwise, returns false.- p
the predicate to test
- Annotations
- @inline()
-
final
def
filter(p: (A) ⇒ Boolean): Option[A]
Returns this scala.Option if it is nonempty and applying the predicate
p
to this scala.Option's value returns true.Returns this scala.Option if it is nonempty and applying the predicate
p
to this scala.Option's value returns true. Otherwise, returnNone
.- p
the predicate used for testing.
- Annotations
- @inline()
-
final
def
filterNot(p: (A) ⇒ Boolean): Option[A]
Returns this scala.Option if it is nonempty and applying the predicate
p
to this scala.Option's value returns false.Returns this scala.Option if it is nonempty and applying the predicate
p
to this scala.Option's value returns false. Otherwise, returnNone
.- p
the predicate used for testing.
- Annotations
- @inline()
-
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. -
def
find(p: (A) ⇒ Boolean): Option[A]
Finds the first element of the iterable collection satisfying a predicate, if any.
Finds the first element of the iterable collection satisfying a predicate, if any.
Note: may not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- p
the predicate used to test elements.
- returns
an option value containing the first element in the iterable collection that satisfies
p
, orNone
if none exists.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
final
def
flatMap[B](f: (A) ⇒ Option[B]): Option[B]
Returns the result of applying
f
to this scala.Option's value if this scala.Option is nonempty.Returns the result of applying
f
to this scala.Option's value if this scala.Option is nonempty. ReturnsNone
if this scala.Option is empty. Slightly different frommap
in thatf
is expected to return an scala.Option (which could beNone
).- f
the function to apply
- Annotations
- @inline()
- See also
map
foreach
- def flatten[B](implicit ev: <:<[A, Option[B]]): Option[B]
-
final
def
fold[B](ifEmpty: ⇒ B)(f: (A) ⇒ B): B
Returns the result of applying
f
to this scala.Option's value if the scala.Option is nonempty.Returns the result of applying
f
to this scala.Option's value if the scala.Option is nonempty. Otherwise, evaluates expressionifEmpty
.- ifEmpty
the expression to evaluate if empty.
- f
the function to apply if nonempty.
- Annotations
- @inline()
- Note
This is equivalent to
scala.Option map f getOrElse ifEmpty
.
-
def
foldLeft[B](z: B)(op: (B, A) ⇒ B): B
Applies a binary operator to a start value and all elements of this iterable collection, going left to right.
Applies a binary operator to a start value and all elements of this iterable collection, going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
- 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 iterable collection, going left to right with the start valuez
on the left:op(...op(z, x_1), x_2, ..., x_n)
where
x1, ..., xn
are the elements of this iterable collection. Returnsz
if this iterable collection is empty.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
def
foldRight[B](z: B)(op: (A, B) ⇒ B): B
Applies a binary operator to all elements of this iterable collection and a start value, going right to left.
Applies a binary operator to all elements of this iterable collection and a start value, going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
- 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 iterable collection, going right to left with the start valuez
on the right:op(x_1, op(x_2, ... op(x_n, z)...))
where
x1, ..., xn
are the elements of this iterable collection. Returnsz
if this iterable collection is empty.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
final
def
forall(p: (A) ⇒ Boolean): Boolean
Returns true if this option is empty or the predicate
p
returns true when applied to this scala.Option's value.Returns true if this option is empty or the predicate
p
returns true when applied to this scala.Option's value.- p
the predicate to test
- Annotations
- @inline()
-
final
def
foreach[U](f: (A) ⇒ U): Unit
Apply the given procedure
f
to the option's value, if it is nonempty.Apply the given procedure
f
to the option's value, if it is nonempty. Otherwise, do nothing.- f
the procedure to apply.
- Annotations
- @inline()
- See also
map
flatMap
-
def
formatted(fmtstr: String): String
Returns string formatted according to given
format
string.Returns string formatted according to given
format
string. Format strings are as forString.format
(@see java.lang.String.format).- Implicit
- This member is added by an implicit conversion from Option[A] to StringFormat[Option[A]] performed by method StringFormat in scala.Predef.
- Definition Classes
- StringFormat
- Annotations
- @inline()
-
final
def
getClass(): Class[_]
Returns the runtime class representation of the object.
-
final
def
getOrElse[B >: A](default: ⇒ B): B
Returns the option's value if the option is nonempty, otherwise return the result of evaluating
default
.Returns the option's value if the option is nonempty, otherwise return the result of evaluating
default
.- default
the default expression.
- Annotations
- @inline()
-
def
groupBy[K](f: (A) ⇒ K): Map[K, collection.Iterable[A]]
Partitions this iterable collection into a map of iterable collections according to some discriminator function.
Partitions this iterable collection into a map of iterable collections according to some discriminator function.
Note: When applied to a view or a lazy collection it will always force the elements.
- K
the type of keys returned by the discriminator function.
- f
the discriminator function.
- returns
A map from keys to iterable collections such that the following invariant holds:
(xs groupBy f)(k) = xs filter (x => f(x) == k)
That is, every key
k
is bound to a iterable collection of those elementsx
for whichf(x)
equalsk
.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
def
groupMap[K, B](key: (A) ⇒ K)(f: (A) ⇒ B): Map[K, collection.Iterable[B]]
Partitions this iterable collection into a map of iterable collections according to a discriminator function
key
.Partitions this iterable collection into a map of iterable collections according to a discriminator function
key
. Each element in a group is transformed into a value of typeB
using thevalue
function.It is equivalent to
groupBy(key).mapValues(_.map(f))
, but more efficient.case class User(name: String, age: Int) def namesByAge(users: Seq[User]): Map[Int, Seq[String]] = users.groupMap(_.age)(_.name)
- 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
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
def
groupMapReduce[K, B](key: (A) ⇒ K)(f: (A) ⇒ B)(reduce: (B, B) ⇒ B): Map[K, B]
Partitions this iterable collection into a map according to a discriminator function
key
.Partitions this iterable collection into a map according to a discriminator function
key
. All the values that have the same discriminator are then transformed by thevalue
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)(_ + _)
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
def
grouped(size: Int): collection.Iterator[collection.Iterable[A]]
Partitions elements in fixed size iterable collections.
Partitions elements in fixed size iterable collections.
- size
the number of elements per group
- returns
An iterator producing iterable collections of size
size
, except the last will be less than sizesize
if the elements don't divide evenly.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
- See also
scala.collection.Iterator, method
grouped
-
def
hashCode(): Int
The hashCode method for reference types.
-
def
head: A
Selects the first element of this iterable collection.
Selects the first element of this iterable collection.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
the first element of this iterable collection.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
- Exceptions thrown
NoSuchElementException
if the iterable collection is empty.
-
def
headOption: Option[A]
Optionally selects the first element.
Optionally selects the first element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
the first element of this iterable collection if it is nonempty,
None
if it is empty.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
def
init: collection.Iterable[A]
The initial part of the collection without its last element.
The initial part of the collection without its last element.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
def
inits: collection.Iterator[collection.Iterable[A]]
Iterates over the inits of this iterable collection.
Iterates over the inits of this iterable collection. The first value will be this iterable collection and the final one will be an empty iterable collection, with the intervening values the results of successive applications of
init
.- returns
an iterator over all the inits of this iterable collection
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)
Example: -
def
isDefined: Boolean
Returns true if the option is an instance of scala.Some, false otherwise.
-
final
def
isInstanceOf[T0]: Boolean
Test whether the dynamic type of the receiver object is
T0
.Test whether the dynamic type of the receiver object is
T0
.Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression
1.isInstanceOf[String]
will returnfalse
, while the expressionList(1).isInstanceOf[List[String]]
will returntrue
. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.- returns
true
if the receiver object is an instance of erasure of typeT0
;false
otherwise.
- Definition Classes
- Any
-
def
iterableFactory: IterableFactory[[X]collection.Iterable[X]]
- returns
The companion object of this iterable collection, providing various factory methods.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- Iterable → IterableOps
-
def
iterator: Iterator[A]
Returns a singleton iterator returning the scala.Option's value if it is nonempty, or an empty iterator if the option is empty.
-
def
knownSize: Int
The number of elements in this iterable collection, if it can be cheaply computed, -1 otherwise.
The number of elements in this iterable collection, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
def
last: A
Selects the last element.
Selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
The last element of this iterable collection.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
- Exceptions thrown
NoSuchElementException
If the iterable collection is empty.
-
def
lastOption: Option[A]
Optionally selects the last element.
Optionally selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
the last element of this iterable collection$ if it is nonempty,
None
if it is empty.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
final
def
map[B](f: (A) ⇒ B): Option[B]
Returns a scala.Some containing the result of applying
f
to this scala.Option's value if this scala.Option is nonempty.Returns a scala.Some containing the result of applying
f
to this scala.Option's value if this scala.Option is nonempty. Otherwise returnNone
.- f
the function to apply
- Annotations
- @inline()
- Note
This is similar to
flatMap
except here,f
does not need to wrap its result in an scala.Option.- See also
flatMap
foreach
-
def
max: A
[use case] Finds the largest element.
[use case]Finds the largest element.
- returns
the largest element of this option.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this option is empty.
Full Signaturedef max[B >: A](implicit ord: math.Ordering[B]): A
-
def
maxBy[B](f: (A) ⇒ B): A
[use case] Finds the first element which yields the largest value measured by function f.
[use case]Finds the first element which yields the largest value measured by function f.
- B
The result type of the function f.
- f
The measuring function.
- returns
the first element of this option with the largest value measured by function f.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this option is empty.
Full Signaturedef maxBy[B](f: (A) ⇒ B)(implicit cmp: math.Ordering[B]): A
-
def
min: A
[use case] Finds the smallest element.
[use case]Finds the smallest element.
- returns
the smallest element of this option
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this option is empty.
Full Signaturedef min[B >: A](implicit ord: math.Ordering[B]): A
-
def
minBy[B](f: (A) ⇒ B): A
[use case] Finds the first element which yields the smallest value measured by function f.
[use case]Finds the first element which yields the smallest value measured by function f.
- B
The result type of the function f.
- f
The measuring function.
- returns
the first element of this option with the smallest value measured by function f.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this option is empty.
Full Signaturedef minBy[B](f: (A) ⇒ B)(implicit cmp: math.Ordering[B]): A
-
def
mkString: String
Displays all elements of this iterable collection in a string.
Displays all elements of this iterable collection in a string.
- returns
a string representation of this iterable collection. In the resulting string the string representations (w.r.t. the method
toString
) of all elements of this iterable collection follow each other without any separator string.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
def
mkString(sep: String): String
Displays all elements of this iterable collection in a string using a separator string.
Displays all elements of this iterable collection in a string using a separator string.
- sep
the separator string.
- returns
a string representation of this iterable collection. In the resulting string the string representations (w.r.t. the method
toString
) of all elements of this iterable collection are separated by the stringsep
.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
List(1, 2, 3).mkString("|") = "1|2|3"
Example: -
def
mkString(start: String, sep: String, end: String): String
Displays all elements of this iterable collection in a string using start, end, and separator strings.
Displays all elements of this iterable collection in a string using start, end, and separator strings.
- start
the starting string.
- sep
the separator string.
- end
the ending string.
- returns
a string representation of this iterable collection. The resulting string begins with the string
start
and ends with the stringend
. Inside, the string representations (w.r.t. the methodtoString
) of all elements of this iterable collection are separated by the stringsep
.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- 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
-
final
def
nonEmpty: Boolean
Returns false if the option is
None
, true otherwise.Returns false if the option is
None
, true otherwise.- Note
Implemented here to avoid the implicit conversion to Iterable.
-
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
-
final
def
orElse[B >: A](alternative: ⇒ Option[B]): Option[B]
Returns this scala.Option if it is nonempty, otherwise return the result of evaluating
alternative
.Returns this scala.Option if it is nonempty, otherwise return the result of evaluating
alternative
.- alternative
the alternative expression.
- Annotations
- @inline()
-
final
def
orNull[A1 >: A](implicit ev: <:<[Null, A1]): A1
Returns the option's value if it is nonempty, or
null
if it is empty.Returns the option's value if it is nonempty, or
null
if it is empty. Although the use of null is discouraged, code written to use scala.Option must often interface with code that expects and returns nulls.- Annotations
- @inline()
val initialText: Option[String] = getInitialText val textField = new JComponent(initialText.orNull,20)
Example: -
def
partition(p: (A) ⇒ Boolean): (collection.Iterable[A], collection.Iterable[A])
A pair of, first, all elements that satisfy prediacte
p
and, second, all elements that do not.A pair of, first, all elements that satisfy prediacte
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
inBuildable
, which requires only a single traversal.- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
def
product: A
[use case] Multiplies up the elements of this collection.
[use case]Multiplies up the elements of this collection.
- returns
the product of all elements in this option of numbers of type
Int
. Instead ofInt
, any other typeT
with an implicitNumeric[T]
implementation can be used as element type of the option and as result type ofproduct
. Examples of such types are:Long
,Float
,Double
,BigInt
.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
Full Signaturedef product[B >: A](implicit num: math.Numeric[B]): B
-
def
productIterator: Iterator[Any]
An iterator over all the elements of this product.
An iterator over all the elements of this product.
- returns
in the default implementation, an
Iterator[Any]
- Definition Classes
- Product
-
def
productPrefix: String
A string used in the
toString
methods of derived classes.A string used in the
toString
methods of derived classes. Implementations may override this method to prepend a string prefix to the result oftoString
methods.- returns
in the default implementation, the empty string
- Definition Classes
- Product
-
def
reduce[B >: A](op: (B, B) ⇒ B): B
Reduces the elements of this iterable collection using the specified associative binary operator.
Reduces the elements of this iterable collection 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 iterable collection is nonempty.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this iterable collection is empty.
-
def
reduceLeft[B >: A](op: (B, A) ⇒ B): B
Applies a binary operator to all elements of this iterable collection, going left to right.
Applies a binary operator to all elements of this iterable collection, going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
- B
the result type of the binary operator.
- op
the binary operator.
- returns
the result of inserting
op
between consecutive elements of this iterable collection, going left to right:op( op( ... op(x_1, x_2) ..., x_{n-1}), x_n)
where
x1, ..., xn
are the elements of this iterable collection.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this iterable collection is empty.
-
def
reduceLeftOption[B >: A](op: (B, A) ⇒ B): Option[B]
Optionally applies a binary operator to all elements of this iterable collection, going left to right.
Optionally applies a binary operator to all elements of this iterable collection, going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
- B
the result type of the binary operator.
- op
the binary operator.
- returns
an option value containing the result of
reduceLeft(op)
if this iterable collection is nonempty,None
otherwise.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
def
reduceOption[B >: A](op: (B, B) ⇒ B): Option[B]
Reduces the elements of this iterable collection, if any, using the specified associative binary operator.
Reduces the elements of this iterable collection, 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.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
def
reduceRight[B >: A](op: (A, B) ⇒ B): B
Applies a binary operator to all elements of this iterable collection, going right to left.
Applies a binary operator to all elements of this iterable collection, going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
- B
the result type of the binary operator.
- op
the binary operator.
- returns
the result of inserting
op
between consecutive elements of this iterable collection, going right to left:op(x_1, op(x_2, ..., op(x_{n-1}, x_n)...))
where
x1, ..., xn
are the elements of this iterable collection.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
- Exceptions thrown
UnsupportedOperationException
if this iterable collection is empty.
-
def
reduceRightOption[B >: A](op: (A, B) ⇒ B): Option[B]
Optionally applies a binary operator to all elements of this iterable collection, going right to left.
Optionally applies a binary operator to all elements of this iterable collection, going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
- B
the result type of the binary operator.
- op
the binary operator.
- returns
an option value containing the result of
reduceRight(op)
if this iterable collection is nonempty,None
otherwise.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
def
scan[B >: A](z: B)(op: (B, B) ⇒ B): collection.Iterable[B]
Computes a prefix scan of the elements of the collection.
Computes a prefix scan of the elements of the collection.
Note: The neutral element
z
may be applied more than once.- B
element type of the resulting collection
- z
neutral element for the operator
op
- op
the associative operator for the scan
- returns
a new iterable collection containing the prefix scan of the elements in this iterable collection
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
def
scanLeft[B](z: B)(op: (B, A) ⇒ B): collection.Iterable[B]
Produces a iterable collection containing cumulative results of applying the operator going left to right, including the initial value.
Produces a iterable collection containing cumulative results of applying the operator going left to right, including the initial value.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- B
the type of the elements in the resulting collection
- z
the initial value
- op
the binary operator applied to the intermediate result and the element
- returns
collection with intermediate results
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps → IterableOnceOps
- Note
Reuse: $consumesAndProducesIterator
-
def
scanRight[B](z: B)(op: (A, B) ⇒ B): collection.Iterable[B]
Produces a collection containing cumulative results of applying the operator going right to left.
Produces a collection containing cumulative results of applying the operator going right to left. The head of the collection is the last cumulative result.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
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
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
def
size: Int
The size of this iterable collection.
The size of this iterable collection.
Note: will not terminate for infinite-sized collections.
- returns
the number of elements in this iterable collection.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
def
slice(from: Int, until: Int): collection.Iterable[A]
Selects an interval of elements.
Selects an interval of elements. The returned iterable collection is made up of all elements
x
which satisfy the invariant:from <= indexOf(x) < until
Note: might return different results for different runs, unless the underlying collection type is ordered.
- from
the lowest index to include from this iterable collection.
- until
the lowest index to EXCLUDE from this iterable collection.
- returns
a iterable collection containing the elements greater than or equal to index
from
extending up to (but not including) indexuntil
of this iterable collection.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps → IterableOnceOps
- Note
Reuse: $consumesAndProducesIterator
-
def
sliding(size: Int, step: Int): collection.Iterator[collection.Iterable[A]]
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
- size
the number of elements per group
- step
the distance between the first elements of successive groups
- returns
An iterator producing iterable collections of size
size
, except the last element (which may be the only element) will be truncated if there are fewer thansize
elements remaining to be grouped.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
- See also
scala.collection.Iterator, method
sliding
-
def
sliding(size: Int): collection.Iterator[collection.Iterable[A]]
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in
grouped
.) The "sliding window" step is set to one.Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in
grouped
.) The "sliding window" step is set to one.- size
the number of elements per group
- returns
An iterator producing iterable collections of size
size
, except the last element (which may be the only element) will be truncated if there are fewer thansize
elements remaining to be grouped.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
- See also
scala.collection.Iterator, method
sliding
-
def
span(p: (A) ⇒ Boolean): (collection.Iterable[A], collection.Iterable[A])
Splits this iterable collection into a prefix/suffix pair according to a predicate.
Splits this iterable collection into a prefix/suffix pair according to a predicate.
Note:
c span p
is equivalent to (but possibly more efficient than)(c takeWhile p, c dropWhile p)
, provided the evaluation of the predicatep
does not cause any side-effects.Note: might return different results for different runs, unless the underlying collection type is ordered.
- p
the test predicate
- returns
a pair consisting of the longest prefix of this iterable collection whose elements all satisfy
p
, and the rest of this iterable collection.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps → IterableOnceOps
- Note
Reuse: $consumesOneAndProducesTwoIterators
-
def
splitAt(n: Int): (collection.Iterable[A], collection.Iterable[A])
Splits this iterable collection into two at a given position.
Splits this iterable collection into two at a given position. Note:
c splitAt n
is equivalent to (but possibly more efficient than)(c take n, c drop n)
.Note: might return different results for different runs, unless the underlying collection type is ordered.
- n
the position at which to split.
- returns
a pair of iterable collections consisting of the first
n
elements of this iterable collection, and the other elements.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
def
sum: A
[use case] Sums up the elements of this collection.
[use case]Sums up the elements of this collection.
- returns
the sum of all elements in this option of numbers of type
Int
. Instead ofInt
, any other typeT
with an implicitNumeric[T]
implementation can be used as element type of the option and as result type ofsum
. Examples of such types are:Long
,Float
,Double
,BigInt
.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
Full Signaturedef sum[B >: A](implicit num: math.Numeric[B]): B
-
final
def
synchronized[T0](arg0: ⇒ T0): T0
- Definition Classes
- AnyRef
-
def
tail: collection.Iterable[A]
The rest of the collection without its first element.
The rest of the collection without its first element.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
def
tails: collection.Iterator[collection.Iterable[A]]
Iterates over the tails of this iterable collection.
Iterates over the tails of this iterable collection. The first value will be this iterable collection and the final one will be an empty iterable collection, with the intervening values the results of successive applications of
tail
.- returns
an iterator over all the tails of this iterable collection
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)
Example: -
def
take(n: Int): collection.Iterable[A]
Selects first n elements.
Selects first n elements.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- n
the number of elements to take from this iterable collection.
- returns
a iterable collection consisting only of the first
n
elements of this iterable collection, or else the whole iterable collection, if it has less thann
elements. Ifn
is negative, returns an empty iterable collection.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps → IterableOnceOps
- Note
Reuse: $consumesAndProducesIterator
-
def
takeRight(n: Int): collection.Iterable[A]
A collection containing the last
n
elements of this collection.A collection containing the last
n
elements of this collection.- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
def
takeWhile(p: (A) ⇒ Boolean): collection.Iterable[A]
Takes longest prefix of elements that satisfy a predicate.
Takes longest prefix of elements that satisfy a predicate.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- p
The predicate used to test elements.
- returns
the longest prefix of this iterable collection whose elements all satisfy the predicate
p
.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps → IterableOnceOps
- Note
Reuse: $consumesAndProducesIterator
-
def
to[C1](factory: Factory[A, 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]
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
def
toArray[B >: A](implicit arg0: ClassTag[B]): Array[B]
Convert collection to array.
Convert collection to array.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
def
toIndexedSeq: collection.immutable.IndexedSeq[A]
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
final
def
toIterable: collection.Iterable[A]
- returns
This collection as an
Iterable[A]
. No new collection will be built ifthis
is already anIterable[A]
.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- Iterable → IterableOps
-
final
def
toLeft[X](right: ⇒ X): Either[A, X]
Returns a scala.util.Right containing the given argument
right
if this is empty, or a scala.util.Left containing this scala.Option's value if this scala.Option is nonempty.Returns a scala.util.Right containing the given argument
right
if this is empty, or a scala.util.Left containing this scala.Option's value if this scala.Option is nonempty.- right
the expression to evaluate and return if this is empty
- Annotations
- @inline()
- See also
toRight
-
def
toList: List[A]
Returns a singleton list containing the scala.Option's value if it is nonempty, or the empty list if the scala.Option is empty.
-
def
toMap[K, V](implicit ev: <:<[A, (K, V)]): Map[K, V]
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
final
def
toRight[X](left: ⇒ X): Either[X, A]
Returns a scala.util.Left containing the given argument
left
if this scala.Option is empty, or a scala.util.Right containing this scala.Option's value if this is nonempty.Returns a scala.util.Left containing the given argument
left
if this scala.Option is empty, or a scala.util.Right containing this scala.Option's value if this is nonempty.- left
the expression to evaluate and return if this is empty
- Annotations
- @inline()
- See also
toLeft
-
def
toSeq: collection.immutable.Seq[A]
- returns
This collection as a
Seq[A]
. This is equivalent toto(Seq)
but might be faster.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
def
toSet[B >: A]: Set[B]
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
def
toString(): String
Creates a String representation of this object.
Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.
- returns
a String representation of the object.
- Definition Classes
- AnyRef → Any
-
def
toVector: collection.immutable.Vector[A]
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
-
def
transpose[B](implicit asIterable: (A) ⇒ collection.Iterable[B]): collection.Iterable[collection.Iterable[B]]
Transposes this iterable collection of iterable collections into a iterable collection of iterable collections.
Transposes this iterable collection of iterable collections into a iterable collection of iterable collections.
The resulting collection's type will be guided by the static type of iterable collection. For example:
val xs = List( Set(1, 2, 3), Set(4, 5, 6)).transpose // xs == List( // List(1, 4), // List(2, 5), // List(3, 6)) val ys = Vector( List(1, 2, 3), List(4, 5, 6)).transpose // ys == Vector( // Vector(1, 4), // Vector(2, 5), // Vector(3, 6))
- B
the type of the elements of each iterable collection.
- asIterable
an implicit conversion which asserts that the element type of this iterable collection is an
Iterable
.- returns
a two-dimensional iterable collection of iterable collections which has as nth row the nth column of this iterable collection.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
- Exceptions thrown
IllegalArgumentException
if all collections in this iterable collection are not of the same size.
-
def
unzip[A1, A2](implicit asPair: (A) ⇒ (A1, A2)): (collection.Iterable[A1], collection.Iterable[A2])
Converts this iterable collection of pairs into two collections of the first and second half of each pair.
Converts this iterable collection of pairs into two collections of the first and second half of each pair.
val xs = `Iterable`( (1, "one"), (2, "two"), (3, "three")).unzip // xs == (`Iterable`(1, 2, 3), // `Iterable`(one, two, three))
- A1
the type of the first half of the element pairs
- A2
the type of the second half of the element pairs
- asPair
an implicit conversion which asserts that the element type of this iterable collection is a pair.
- returns
a pair of iterable collections, containing the first, respectively second half of each element pair of this iterable collection.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
def
unzip3[A1, A2, A3](implicit asTriple: (A) ⇒ (A1, A2, A3)): (collection.Iterable[A1], collection.Iterable[A2], collection.Iterable[A3])
Converts this iterable collection of triples into three collections of the first, second, and third element of each triple.
Converts this iterable collection of triples into three collections of the first, second, and third element of each triple.
val xs = `Iterable`( (1, "one", '1'), (2, "two", '2'), (3, "three", '3')).unzip3 // xs == (`Iterable`(1, 2, 3), // `Iterable`(one, two, three), // `Iterable`(1, 2, 3))
- A1
the type of the first member of the element triples
- A2
the type of the second member of the element triples
- A3
the type of the third member of the element triples
- asTriple
an implicit conversion which asserts that the element type of this iterable collection is a triple.
- returns
a triple of iterable collections, containing the first, second, respectively third member of each element triple of this iterable collection.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
def
view: View[A]
A view over the elements of this collection.
A view over the elements of this collection.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
final
def
wait(): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
final
def
wait(arg0: Long, arg1: Int): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
- final def wait(arg0: Long): Unit
-
final
def
withFilter(p: (A) ⇒ Boolean): WithFilter
Necessary to keep scala.Option from being implicitly converted to scala.collection.Iterable in
for
comprehensions.Necessary to keep scala.Option from being implicitly converted to scala.collection.Iterable in
for
comprehensions.- Annotations
- @inline()
-
def
zip[B](that: collection.Iterable[B]): collection.Iterable[(A, B)]
Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs.
Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs. If one of the two collections is longer than the other, its remaining elements are ignored.
- B
the type of the second half of the returned pairs
- that
The iterable providing the second half of each result pair
- returns
a new iterable collection containing pairs consisting of corresponding elements of this iterable collection and
that
. The length of the returned collection is the minimum of the lengths of this iterable collection andthat
.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
def
zipAll[A1 >: A, B](that: collection.Iterable[B], thisElem: A1, thatElem: B): collection.Iterable[(A1, B)]
Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs.
Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.
- that
the iterable providing the second half of each result pair
- thisElem
the element to be used to fill up the result if this iterable collection is shorter than
that
.- thatElem
the element to be used to fill up the result if
that
is shorter than this iterable collection.- returns
a new collection of type
That
containing pairs consisting of corresponding elements of this iterable collection andthat
. The length of the returned collection is the maximum of the lengths of this iterable collection andthat
. If this iterable collection is shorter thanthat
,thisElem
values are used to pad the result. Ifthat
is shorter than this iterable collection,thatElem
values are used to pad the result.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
-
def
zipWithIndex: collection.Iterable[(A, Int)]
Zips this iterable collection with its indices.
Zips this iterable collection with its indices.
- returns
A new iterable collection containing pairs consisting of all elements of this iterable collection paired with their index. Indices start at
0
.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps → IterableOnceOps
List("a", "b", "c").zipWithIndex == List(("a", 0), ("b", 1), ("c", 2))
- Note
Reuse: $consumesAndProducesIterator
Example: -
def
→[B](y: B): (Option[A], B)
- Implicit
- This member is added by an implicit conversion from Option[A] to ArrowAssoc[Option[A]] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
Shadowed Implicit Value Members
-
def
collect[B](pf: PartialFunction[A, B]): collection.Iterable[B]
Builds a new iterable collection by applying a partial function to all elements of this iterable collection on which the function is defined.
Builds a new iterable collection by applying a partial function to all elements of this iterable collection on which the function is defined.
- B
the element type of the returned iterable collection.
- pf
the partial function which filters and maps the iterable collection.
- returns
a new iterable collection resulting from applying the given partial function
pf
to each element on which it is defined and collecting the results. The order of the elements is preserved.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(option: Iterable[A]).collect(pf)
- Definition Classes
- IterableOps → IterableOnceOps
- Note
Reuse: $consumesAndProducesIterator
-
def
exists(p: (A) ⇒ Boolean): Boolean
Tests whether a predicate holds for at least one element of this iterable collection.
Tests whether a predicate holds for at least one element of this iterable collection.
Note: may not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
true
if the given predicatep
is satisfied by at least one element of this iterable collection, otherwisefalse
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(option: Iterable[A]).exists(p)
- Definition Classes
- IterableOnceOps
-
def
filter(pred: (A) ⇒ Boolean): collection.Iterable[A]
Selects all elements of this iterable collection which satisfy a predicate.
Selects all elements of this iterable collection which satisfy a predicate.
- returns
a new iterator consisting of all elements of this iterable collection that satisfy the given predicate
p
. The order of the elements is preserved.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(option: Iterable[A]).filter(pred)
- Definition Classes
- IterableOps → IterableOnceOps
-
def
filterNot(pred: (A) ⇒ Boolean): collection.Iterable[A]
Selects all elements of this iterable collection which do not satisfy a predicate.
Selects all elements of this iterable collection which do not satisfy a predicate.
- pred
the predicate used to test elements.
- returns
a new iterable collection consisting of all elements of this iterable collection that do not satisfy the given predicate
pred
. Their order may not be preserved.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(option: Iterable[A]).filterNot(pred)
- Definition Classes
- IterableOps → IterableOnceOps
-
def
flatMap[B](f: (A) ⇒ collection.IterableOnce[B]): collection.Iterable[B]
Builds a new iterable collection by applying a function to all elements of this iterable collection and using the elements of the resulting collections.
Builds a new iterable collection by applying a function to all elements of this iterable collection and using the elements of the resulting collections.
For example:
def getWords(lines: Seq[String]): Seq[String] = lines flatMap (line => line split "\\W+")
The type of the resulting collection is guided by the static type of iterable collection. This might cause unexpected results sometimes. For example:
// lettersOf will return a Seq[Char] of likely repeated letters, instead of a Set def lettersOf(words: Seq[String]) = words flatMap (word => word.toSet) // lettersOf will return a Set[Char], not a Seq def lettersOf(words: Seq[String]) = words.toSet flatMap (word => word.toSeq) // xs will be an Iterable[Int] val xs = Map("a" -> List(11,111), "b" -> List(22,222)).flatMap(_._2) // ys will be a Map[Int, Int] val ys = Map("a" -> List(1 -> 11,1 -> 111), "b" -> List(2 -> 22,2 -> 222)).flatMap(_._2)
- B
the element type of the returned collection.
- f
the function to apply to each element.
- returns
a new iterable collection resulting from applying the given collection-valued function
f
to each element of this iterable collection and concatenating the results.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(option: Iterable[A]).flatMap(f)
- Definition Classes
- IterableOps → IterableOnceOps
- Note
Reuse: $consumesAndProducesIterator
-
def
flatten[B](implicit asIterable: (A) ⇒ collection.IterableOnce[B]): collection.Iterable[B]
Converts this iterable collection of traversable collections into a iterable collection formed by the elements of these traversable collections.
Converts this iterable collection of traversable collections into a iterable collection formed by the elements of these traversable collections.
The resulting collection's type will be guided by the type of iterable collection. For example:
val xs = List( Set(1, 2, 3), Set(1, 2, 3) ).flatten // xs == List(1, 2, 3, 1, 2, 3) val ys = Set( List(1, 2, 3), List(3, 2, 1) ).flatten // ys == Set(1, 2, 3)
- B
the type of the elements of each traversable collection.
- asIterable
an implicit conversion which asserts that the element type of this iterable collection is a
GenTraversable
.- returns
a new iterable collection resulting from concatenating all element iterable collections.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(option: Iterable[A]).flatten(asIterable)
- Definition Classes
- IterableOps → IterableOnceOps
- Note
Reuse: $consumesAndProducesIterator
-
def
forall(p: (A) ⇒ Boolean): Boolean
Tests whether a predicate holds for all elements of this iterable collection.
Tests whether a predicate holds for all elements of this iterable collection.
Note: may not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
true
if this iterable collection is empty or the given predicatep
holds for all elements of this iterable collection, otherwisefalse
.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(option: Iterable[A]).forall(p)
- Definition Classes
- IterableOnceOps
-
def
foreach[U](f: (A) ⇒ U): Unit
Apply
f
to each element for its side effects Note: [U] parameter needed to help scalac's type inference.Apply
f
to each element for its side effects Note: [U] parameter needed to help scalac's type inference.- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(option: Iterable[A]).foreach(f)
- Definition Classes
- IterableOnceOps
-
def
isEmpty: Boolean
Tests whether the iterable collection is empty.
Tests whether the iterable collection is empty.
Note: Implementations in subclasses that are not repeatedly traversable must take care not to consume any elements when
isEmpty
is called.- returns
true
if the iterable collection contains no elements,false
otherwise.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(option: Iterable[A]).isEmpty
- Definition Classes
- IterableOnceOps
-
def
iterator(): collection.Iterator[A]
Iterator can be used only once
Iterator can be used only once
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(option: Iterable[A]).iterator()
- Definition Classes
- IterableOnce
-
def
map[B](f: (A) ⇒ B): collection.Iterable[B]
Builds a new iterable collection by applying a function to all elements of this iterable collection.
Builds a new iterable collection by applying a function to all elements of this iterable collection.
- B
the element type of the returned iterable collection.
- f
the function to apply to each element.
- returns
a new iterable collection resulting from applying the given function
f
to each element of this iterable collection and collecting the results.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(option: Iterable[A]).map(f)
- Definition Classes
- IterableOps → IterableOnceOps
- Note
Reuse: $consumesAndProducesIterator
-
def
nonEmpty: Boolean
Tests whether the iterable collection is not empty.
Tests whether the iterable collection is not empty.
- returns
true
if the iterable collection contains at least one element,false
otherwise.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(option: Iterable[A]).nonEmpty
- Definition Classes
- IterableOnceOps
- Annotations
- @deprecatedOverriding( message = ... , since = "2.13.0" )
-
def
toList: collection.immutable.List[A]
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(option: Iterable[A]).toList
- Definition Classes
- IterableOnceOps
-
def
toString(): String
Converts this iterable collection to a string.
Converts this iterable collection to a string.
- returns
a string representation of this collection. By default this string consists of the
className
of this iterable collection, followed by all elements separated by commas and enclosed in parentheses.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(option: Iterable[A]).toString()
- Definition Classes
- IterableOps → Any
-
def
withFilter(p: (A) ⇒ Boolean): collection.WithFilter[A, collection.Iterable]
Creates a non-strict filter of this iterable collection.
Creates a non-strict filter of this iterable collection.
Note: the difference between
c filter p
andc withFilter p
is that the former creates a new collection, whereas the latter only restricts the domain of subsequentmap
,flatMap
,foreach
, andwithFilter
operations.Note: might return different results for different runs, unless the underlying collection type is ordered.
- p
the predicate used to test elements.
- returns
an object of class
WithFilter
, which supportsmap
,flatMap
,foreach
, andwithFilter
operations. All these operations apply to those elements of this iterable collection which satisfy the predicatep
.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(option: Iterable[A]).withFilter(p)
- Definition Classes
- IterableOps
Deprecated Value Members
-
final
def
/:[B](z: B)(op: (B, A) ⇒ B): B
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use foldLeft instead of /:
-
final
def
:\[B](z: B)(op: (A, B) ⇒ B): B
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use foldRight instead of :\
-
final
def
hasDefiniteSize: Boolean
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use .knownSize >=0 instead of .hasDefiniteSize
-
final
def
stringPrefix: String
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use className instead of stringPrefix
-
final
def
toBuffer[B >: A]: Buffer[B]
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use ArrayBuffer.from(it) instead of it.toBuffer
-
final
def
toIterator: collection.Iterator[A]
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use .iterator() instead of .toIterator
-
final
def
toStream: collection.immutable.Stream[A]
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOnceOps
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use Stream.from(it) instead of it.toStream
-
final
def
view(from: Int, until: Int): View[A]
A view over a slice of the elements of this collection.
A view over a slice of the elements of this collection.
- Implicit
- This member is added by an implicit conversion from Option[A] to Iterable[A] performed by method option2Iterable in scala.Option.
- Definition Classes
- IterableOps
- Annotations
- @deprecated @inline()
- 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
.