Scala Library
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scala/Option.scala
]
sealed abstract
class
Option[+A]
extends
ProductOption
are either instances of case class Some
or it is case
object None
.Method Summary | |
def
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elements
: Iterator[A]
An singleton iterator returning the option's value if it is nonempty
or the empty iterator if the option is empty.
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def
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filter
(p : (A) => Boolean) : Option[A]
If the option is nonempty and the given predicate
p
yields false on its value, return None .
Otherwise return the option value itself. |
def
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flatMap
[B](f : (A) => Option[B]) : Option[B]
If the option is nonempty, return a function applied to its value.
Otherwise return None.
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def
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foreach
(f : (A) => Unit) : Unit
Apply the given procedure
f to the option's value,
if it is nonempty. Do nothing if it is empty. |
abstract def
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get
: A
get the value of this option.
@requires that the option is nonEmpty.
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def
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get [B >: A](default : B) : B |
def
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getOrElse
[B >: A](default : => B) : B
If the option is nonempty return its value,
otherwise return the result of evaluating a default expression.
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def
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isDefined
: Boolean
True if the option is a
Some (...) false otherwise. |
abstract def
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isEmpty
: Boolean
True if the option is the
None value, false otherwise. |
def
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map
[B](f : (A) => B) : Option[B]
If the option is nonempty, return a function applied to its value,
wrapped in a Some i.e.
Some(f(this.get)) .
Otherwise return None . |
def
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orElse
[B >: A](alternative : => Option[B]) : Option[B]
If the option is nonempty return it,
otherwise return the result of evaluating an alternative expression.
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def
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toLeft
[X](right : => X) : Either[A, X] with Product
An
Either that is a Right with the given argument
right if this is empty, or a Left if this is nonempty with the
option's value. |
def
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toList
: List[A]
A singleton list containing the option's value if it is nonempty
or the empty list if the option is empty.
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def
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toRight
[X](left : => X) : Either[X, A] with Product
An
Either that is a Left with the given argument
left if this is empty, or a Right if this is nonempty with the
option's value. |
Methods inherited from Product | |
productElement (abstract), productArity (abstract), productPrefix |
Methods inherited from AnyRef | |
getClass, hashCode, equals, clone, toString, notify, notifyAll, wait, wait, wait, finalize, ==, !=, eq, ne, synchronized |
Methods inherited from Any | |
==, !=, isInstanceOf, asInstanceOf |
Method Details |
abstract
def
isEmpty : Boolean
None
value, false otherwise.
def
isDefined : Boolean
Some
(...) false otherwise.abstract
def
get : A
def
get[B >: A](default : B) : B
getOrElse
insteaddefault -
the default expression.Some(f(this.get))
.
Otherwise return None
.f -
the function to applyf -
the function to applyp
yields false
on its value, return None
.
Otherwise return the option value itself.p -
the predicate used for testing.f
to the option's value,
if it is nonempty. Do nothing if it is empty.f -
the procedure to apply.alternative -
the alternative expression.Either
that is a Left
with the given argument
left
if this is empty, or a Right
if this is nonempty with the
option's value.Either
that is a Right
with the given argument
right
if this is empty, or a Left
if this is nonempty with the
option's value.
Scala Library
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