LazyList

Companion object LazyList

final class LazyList[+A] extends AbstractSeq[A] with LinearSeq[A] with LinearSeqOps[A, LazyList, LazyList[A]] with IterableFactoryDefaults[A, LazyList] with Serializable

This class implements an immutable linked list. We call it "lazy" because it computes its elements only when they are needed.

Elements are memoized; that is, the value of each element is computed at most once.

Elements are computed in-order and are never skipped. In other words, accessing the tail causes the head to be computed first.

How lazy is a LazyList? When you have a value of type LazyList, you don't know yet whether the list is empty or not. If you learn that it is non-empty, then you also know that the head has been computed. But the tail is itself a LazyList, whose emptiness-or-not might remain undetermined.

A LazyList may be infinite. For example, LazyList.from(0) contains all of the natural numbers 0, 1, 2, and so on. For infinite sequences, some methods (such as count, sum, max or min) will not terminate.

Here is an example:

import scala.math.BigInt
object Main extends App {
  val fibs: LazyList[BigInt] =
    BigInt(0) #:: BigInt(1) #:: fibs.zip(fibs.tail).map{ n => n._1 + n._2 }
  fibs.take(5).foreach(println)
}

// prints
//
// 0
// 1
// 1
// 2
// 3

To illustrate, let's add some output to the definition fibs, so we see what's going on.

import scala.math.BigInt
object Main extends App {
  val fibs: LazyList[BigInt] =
    BigInt(0) #:: BigInt(1) #::
      fibs.zip(fibs.tail).map{ n =>
        println(s"Adding ${n._1} and ${n._2}")
        n._1 + n._2
      }
  fibs.take(5).foreach(println)
  fibs.take(6).foreach(println)
}

// prints
//
// 0
// 1
// Adding 0 and 1
// 1
// Adding 1 and 1
// 2
// Adding 1 and 2
// 3

// And then prints
//
// 0
// 1
// 1
// 2
// 3
// Adding 2 and 3
// 5

Note that the definition of fibs uses val not def. The memoization of the LazyList requires us to have somewhere to store the information and a val allows us to do that.

Further remarks about the semantics of LazyList:

Though the LazyList changes as it is accessed, this does not contradict its immutability. Once the values are memoized they do not change. Values that have yet to be memoized still "exist", they simply haven't been computed yet.
One must be cautious of memoization; it can eat up memory if you're not careful. That's because memoization of the LazyList creates a structure much like scala.collection.immutable.List. As long as something is holding on to the head, the head holds on to the tail, and so on recursively. If, on the other hand, there is nothing holding on to the head (e.g. if we used def to define the LazyList) then once it is no longer being used directly, it disappears.
Note that some operations, including drop, dropWhile, flatMap or collect may process a large number of intermediate elements before returning.

Here's another example. Let's start with the natural numbers and iterate over them.

// We'll start with a silly iteration
def loop(s: String, i: Int, iter: Iterator[Int]): Unit = {
  // Stop after 200,000
  if (i < 200001) {
    if (i % 50000 == 0) println(s + i)
    loop(s, iter.next(), iter)
  }
}

// Our first LazyList definition will be a val definition
val lazylist1: LazyList[Int] = {
  def loop(v: Int): LazyList[Int] = v #:: loop(v + 1)
  loop(0)
}

// Because lazylist1 is a val, everything that the iterator produces is held
// by virtue of the fact that the head of the LazyList is held in lazylist1
val it1 = lazylist1.iterator
loop("Iterator1: ", it1.next(), it1)

// We can redefine this LazyList such that all we have is the Iterator left
// and allow the LazyList to be garbage collected as required.  Using a def
// to provide the LazyList ensures that no val is holding onto the head as
// is the case with lazylist1
def lazylist2: LazyList[Int] = {
  def loop(v: Int): LazyList[Int] = v #:: loop(v + 1)
  loop(0)
}
val it2 = lazylist2.iterator
loop("Iterator2: ", it2.next(), it2)

// And, of course, we don't actually need a LazyList at all for such a simple
// problem.  There's no reason to use a LazyList if you don't actually need
// one.
val it3 = new Iterator[Int] {
  var i = -1
  def hasNext = true
  def next(): Int = { i += 1; i }
}
loop("Iterator3: ", it3.next(), it3)

In the fibs example earlier, the fact that tail works at all is of interest. fibs has an initial (0, 1, LazyList(...)), so tail is deterministic. If we defined fibs such that only 0 were concretely known, then the act of determining tail would require the evaluation of tail, so the computation would be unable to progress, as in this code:

// The first time we try to access the tail we're going to need more
// information which will require us to recurse, which will require us to
// recurse, which...
lazy val sov: LazyList[Vector[Int]] = Vector(0) #:: sov.zip(sov.tail).map { n => n._1 ++ n._2 }

The definition of fibs above creates a larger number of objects than necessary depending on how you might want to implement it. The following implementation provides a more "cost effective" implementation due to the fact that it has a more direct route to the numbers themselves:

lazy val fib: LazyList[Int] = {
  def loop(h: Int, n: Int): LazyList[Int] = h #:: loop(n, h + n)
  loop(1, 1)
}

The head, the tail and whether the list is empty or not can be initially unknown. Once any of those are evaluated, they are all known, though if the tail is built with #:: or #:::, it's content still isn't evaluated. Instead, evaluating the tails content is deferred until the tails empty status, head or tail is evaluated.

Delaying the evaluation of whether a LazyList is empty or not until it's needed allows LazyList to not eagerly evaluate any elements on a call to filter.

Only when it's further evaluated (which may be never!) any of the elements gets forced.

for example:

def tailWithSideEffect: LazyList[Nothing] = {
  println("getting empty LazyList")
  LazyList.empty
}

val emptyTail = tailWithSideEffect // prints "getting empty LazyList"

val suspended = 1 #:: tailWithSideEffect // doesn't print anything
val tail = suspended.tail // although the tail is evaluated, *still* nothing is yet printed
val filtered = tail.filter(_ => false) // still nothing is printed
filtered.isEmpty // prints "getting empty LazyList"

A: the type of the elements contained in this lazy list.

Annotations: @SerialVersionUID()
Source: LazyList.scala
See also: "Scala's Collection Library overview" section on LazyLists for more information.

Linear Supertypes

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

Type Hierarchy

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LazyList
Serializable
LinearSeq
LinearSeqOps
LinearSeq
LinearSeqOps
AbstractSeq
Seq
SeqOps
Iterable
AbstractSeq
Seq
Equals
SeqOps
PartialFunction
Function1
AbstractIterable
Iterable
IterableFactoryDefaults
IterableOps
IterableOnceOps
IterableOnce
AnyRef
Any

Implicitly

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

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Value Members

final def !=(arg0: Any): Boolean
Test two objects for inequality.
Test two objects for inequality.
returns
true if !(this == that), false otherwise.
Definition Classes
AnyRef → Any
final def ##: Int
Equivalent to x.hashCode except for boxed numeric types and null.
Equivalent to x.hashCode except for boxed numeric types and null. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For null returns a hashcode where null.hashCode throws a NullPointerException.
returns
a hash value consistent with ==
Definition Classes
AnyRef → Any
def #::[B >: A](elem: => B): LazyList[B]
Construct a LazyList consisting of a given first element followed by elements from another LazyList.
Construct a LazyList consisting of a given first element followed by elements from another LazyList.
Implicit
This member is added by an implicit conversion from LazyList[A] toDeferrer[A] performed by method toDeferrer in scala.collection.immutable.LazyList.
Definition Classes
Deferrer
def #:::[B >: A](prefix: LazyList[B]): LazyList[B]
Construct a LazyList consisting of the concatenation of the given LazyList and another LazyList.
Construct a LazyList consisting of the concatenation of the given LazyList and another LazyList.
Implicit
This member is added by an implicit conversion from LazyList[A] toDeferrer[A] performed by method toDeferrer in scala.collection.immutable.LazyList.
Definition Classes
Deferrer
def +(other: String): String
Implicit
This member is added by an implicit conversion from LazyList[A] toany2stringadd[LazyList[A]] performed by method any2stringadd in scala.Predef.
Definition Classes
any2stringadd
final def ++[B >: A](suffix: IterableOnce[B]): LazyList[B]
Alias for concat
Alias for concat
Definition Classes
IterableOps
Annotations
@inline()
final def ++:[B >: A](prefix: IterableOnce[B]): LazyList[B]
Alias for prependedAll
Alias for prependedAll
Definition Classes
SeqOps → IterableOps
Annotations
@inline()
final def +:[B >: A](elem: B): LazyList[B]
Alias for prepended.
Alias for prepended.
Note that :-ending operators are right associative (see example). A mnemonic for +: vs. :+ is: the COLon goes on the COLlection side.
Definition Classes
SeqOps
Annotations
@inline()
def ->[B](y: B): (LazyList[A], B)
Implicit
This member is added by an implicit conversion from LazyList[A] toArrowAssoc[LazyList[A]] performed by method ArrowAssoc in scala.Predef.This conversion will take place only if A is a subclass of Option[Nothing] (A <: Option[Nothing]).
Definition Classes
ArrowAssoc
Annotations
@inline()
final def :+[B >: A](elem: B): LazyList[B]
Alias for appended
Alias for appended
Note that :-ending operators are right associative (see example). A mnemonic for +: vs. :+ is: the COLon goes on the COLlection side.
Definition Classes
SeqOps
Annotations
@inline()
final def :++[B >: A](suffix: IterableOnce[B]): LazyList[B]
Alias for appendedAll
Alias for appendedAll
Definition Classes
SeqOps
Annotations
@inline()
final def ==(arg0: Any): Boolean
The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).
The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).
returns
true if the receiver object is equivalent to the argument; false otherwise.
Definition Classes
AnyRef → Any
def addString(sb: mutable.StringBuilder, start: String, sep: String, end: String): mutable.StringBuilder
Appends all elements of this lazy list to a string builder using start, end, and separator strings.
Appends all elements of this lazy list to a string builder using start, end, and separator strings. The written text begins with the string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this lazy list are separated by the string sep.
An undefined state is represented with "<not computed>" and cycles are represented with "<cycle>".
This method evaluates all elements of the collection.
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
LazyList → IterableOnceOps
final def addString(b: mutable.StringBuilder): mutable.StringBuilder
Appends all elements of this collection to a string builder.
Appends all elements of this collection to a string builder. The written text consists of the string representations (w.r.t. the method toString) of all elements of this collection without any separator string.
Example:
```
scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

scala> val h = a.addString(b)
h: StringBuilder = 1234
```
b
the string builder to which elements are appended.
returns
the string builder b to which elements were appended.
Definition Classes
IterableOnceOps
Annotations
@inline()
final def addString(b: mutable.StringBuilder, sep: String): mutable.StringBuilder
Appends all elements of this collection to a string builder using a separator string.
Appends all elements of this 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 collection, separated by the string sep.
Example:
```
scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

scala> a.addString(b, ", ")
res0: StringBuilder = 1, 2, 3, 4
```
b
the string builder to which elements are appended.
sep
the separator string.
returns
the string builder b to which elements were appended.
Definition Classes
IterableOnceOps
Annotations
@inline()
def andThen[C](k: PartialFunction[A, C]): PartialFunction[Int, C]
Composes this partial function with another partial function that gets applied to results of this partial function.
Composes this partial function with another partial function that gets applied to results of this partial function.
Note that calling isDefinedAt on the resulting partial function may apply the first partial function and execute its side effect. It is highly recommended to call applyOrElse instead of isDefinedAt / apply for efficiency.
C
the result type of the transformation function.
k
the transformation function
returns
a partial function with the domain of this partial function narrowed by other partial function, which maps arguments x to k(this(x)).
Definition Classes
PartialFunction
def andThen[C](k: (A) => C): PartialFunction[Int, C]
Composes this partial function with a transformation function that gets applied to results of this partial function.
Composes this partial function with a transformation function that gets applied to results of this partial function.
If the runtime type of the function is a PartialFunction then the other andThen method is used (note its cautions).
C
the result type of the transformation function.
k
the transformation function
returns
a partial function with the domain of this partial function, possibly narrowed by the specified function, which maps arguments x to k(this(x)).
Definition Classes
PartialFunction → Function1
def appended[B >: A](elem: B): LazyList[B]
A copy of this lazy list with an element appended.
A copy of this lazy list 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)
```
This method preserves laziness; elements are only evaluated individually as needed.
Note: Repeated chaining of calls to append methods (appended, appendedAll, lazyAppendedAll) without forcing any of the intermediate resulting lazy lists may overflow the stack when the final result is forced.
B
the element type of the returned lazy list.
elem
the appended element
returns
a new lazy list consisting of all elements of this lazy list followed by value.
Definition Classes
LazyList → SeqOps
def appendedAll[B >: A](suffix: IterableOnce[B]): LazyList[B]
Returns a new lazy list containing the elements from the left hand operand followed by the elements from the right hand operand.
Returns a new lazy list containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the lazy list is the most specific superclass encompassing the element types of the two operands.
This method preserves laziness; elements are only evaluated individually as needed.
Note: Repeated chaining of calls to append methods (appended, appendedAll, lazyAppendedAll) without forcing any of the intermediate resulting lazy lists may overflow the stack when the final result is forced.
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 lazy list followed by all elements of suffix.
Definition Classes
LazyList → SeqOps
def apply(n: Int): A
Get the element at the specified index.
Get the element at the specified index. This operation is provided for convenience in Seq. It should not be assumed to be efficient unless you have an IndexedSeq.
Definition Classes
LinearSeqOps → SeqOps
Annotations
@throws(cause = scala.this.throws.<init>$default$1[IndexOutOfBoundsException])
def applyOrElse[A1 <: Int, B1 >: A](x: A1, default: (A1) => B1): B1
Applies this partial function to the given argument when it is contained in the function domain.
Applies this partial function to the given argument when it is contained in the function domain. Applies fallback function where this partial function is not defined.
Note that expression pf.applyOrElse(x, default) is equivalent to
```
if(pf isDefinedAt x) pf(x) else default(x)
```
except that applyOrElse method can be implemented more efficiently. For all partial function literals the compiler generates an applyOrElse implementation which avoids double evaluation of pattern matchers and guards. This makes applyOrElse the basis for the efficient implementation for many operations and scenarios, such as:
- combining partial functions into orElse/andThen chains does not lead to excessive apply/isDefinedAt evaluation
- lift and unlift do not evaluate source functions twice on each invocation
- runWith allows efficient imperative-style combining of partial functions with conditionally applied actions
For non-literal partial function classes with nontrivial isDefinedAt method it is recommended to override applyOrElse with custom implementation that avoids double isDefinedAt evaluation. This may result in better performance and more predictable behavior w.r.t. side effects.
x
the function argument
default
the fallback function
returns
the result of this function or fallback function application.
Definition Classes
PartialFunction
final def asInstanceOf[T0]: T0
Cast the receiver object to be of type T0.
Cast the receiver object to be of type T0.
Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression 1.asInstanceOf[String] will throw a ClassCastException at runtime, while the expression List(1).asInstanceOf[List[String]] will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.
returns
the receiver object.
Definition Classes
Any
Exceptions thrown
ClassCastException if the receiver object is not an instance of the erasure of type T0.
def canEqual(that: Any): Boolean
Method called from equality methods, so that user-defined subclasses can refuse to be equal to other collections of the same kind.
Method called from equality methods, so that user-defined subclasses can refuse to be equal to other collections of the same kind.
that
The object with which this sequence should be compared
returns
true, if this sequence can possibly equal that, false otherwise. The test takes into consideration only the run-time types of objects but ignores their elements.
Definition Classes
Seq → Equals
def className: String
Defines the prefix of this object's toString representation.
Defines the prefix of this object's toString representation.
It is recommended to return the name of the concrete collection type, but not implementation subclasses. For example, for ListMap this method should return "ListMap", not "Map" (the supertype) or "Node" (an implementation subclass).
The default implementation returns "Iterable". It is overridden for the basic collection kinds "Seq", "IndexedSeq", "LinearSeq", "Buffer", "Set", "Map", "SortedSet", "SortedMap" and "View".
returns
a string representation which starts the result of toString applied to this lazy list. By default the string prefix is the simple name of the collection class lazy list.
Attributes
protected[this]
Definition Classes
LazyList → Iterable
def clone(): AnyRef
Create a copy of the receiver object.
Create a copy of the receiver object.
The default implementation of the clone method is platform dependent.
returns
a copy of the receiver object.
Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.CloneNotSupportedException]) @native()
Note
not specified by SLS as a member of AnyRef
final def coll: LazyList.this.type
returns
This collection as a C.
Attributes
protected
Definition Classes
Iterable → IterableOps
def collect[B](pf: PartialFunction[A, B]): LazyList[B]
Builds a new lazy list by applying a partial function to all elements of this lazy list on which the function is defined.
Builds a new lazy list by applying a partial function to all elements of this lazy list on which the function is defined.
This method preserves laziness; elements are only evaluated individually as needed.
B
the element type of the returned lazy list.
pf
the partial function which filters and maps the lazy list.
returns
a new lazy list resulting from applying the given partial function pf to each element on which it is defined and collecting the results. The order of the elements is preserved.
Definition Classes
LazyList → IterableOps → IterableOnceOps
def collectFirst[B](pf: PartialFunction[A, B]): Option[B]
Finds the first element of the lazy list for which the given partial function is defined, and applies the partial function to it.
Finds the first element of the lazy list for which the given partial function is defined, and applies the partial function to it.
Note: may not terminate for infinite-sized collections.
This method does not evaluate any elements further than the first element for which the partial function is defined.
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
LazyList → IterableOnceOps
Annotations
@tailrec()
def combinations(n: Int): Iterator[LazyList[A]]
Iterates over combinations.
Iterates over combinations. A _combination_ of length n is a subsequence of the original sequence, with the elements taken in order. Thus, "xy" and "yy" are both length-2 combinations of "xyy", but "yx" is not. If there is more than one way to generate the same subsequence, only one will be returned.
For example, "xyyy" has three different ways to generate "xy" depending on whether the first, second, or third "y" is selected. However, since all are identical, only one will be chosen. Which of the three will be taken is an implementation detail that is not defined.
Note: Even when applied to a view or a lazy collection it will always force the elements.
returns
An Iterator which traverses the possible n-element combinations of this sequence.
Definition Classes
SeqOps
Example:
1. "abbbc".combinations(2) = Iterator(ab, ac, bb, bc)
def compose[R](k: PartialFunction[R, Int]): PartialFunction[R, A]
Composes another partial function k with this partial function so that this partial function gets applied to results of k.
Composes another partial function k with this partial function so that this partial function gets applied to results of k.
Note that calling isDefinedAt on the resulting partial function may apply the first partial function and execute its side effect. It is highly recommended to call applyOrElse instead of isDefinedAt / apply for efficiency.
R
the parameter type of the transformation function.
k
the transformation function
returns
a partial function with the domain of other partial function narrowed by this partial function, which maps arguments x to this(k(x)).
Definition Classes
PartialFunction
def compose[A](g: (A) => Int): (A) => A
Composes two instances of Function1 in a new Function1, with this function applied last.
Composes two instances of Function1 in a new Function1, with this function applied last.
A
the type to which function g can be applied
g
a function A => T1
returns
a new function f such that f(x) == apply(g(x))
Definition Classes
Function1
Annotations
@unspecialized()
final def concat[B >: A](suffix: IterableOnce[B]): LazyList[B]
Returns a new sequence containing the elements from the left hand operand followed by the elements from the right hand operand.
Returns a new sequence containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the 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 sequence which contains all elements of this sequence followed by all elements of suffix.
Definition Classes
SeqOps → IterableOps
Annotations
@inline()
def contains[A1 >: A](elem: A1): Boolean
Tests whether this sequence contains a given value as an element.
Tests whether this 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 sequence has an element that is equal (as determined by ==) to elem, false otherwise.
Definition Classes
LinearSeqOps → SeqOps
def containsSlice[B](that: collection.Seq[B]): Boolean
Tests whether this sequence contains a given sequence as a slice.
Tests whether this 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 sequence contains a slice with the same elements as that, otherwise false.
Definition Classes
SeqOps
def copyToArray[B >: A](xs: Array[B], start: Int, len: Int): Int
Copy elements to an array, returning the number of elements written.
Copy elements to an array, returning the number of elements written.
Fills the given array xs starting at index start with at most len elements of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached, or len elements have been copied.
B
the type of the elements of the array.
xs
the array to fill.
start
the starting index of xs.
len
the maximal number of elements to copy.
returns
the number of elements written to the array
Definition Classes
IterableOnceOps
Note
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change. Note: will not terminate for infinite-sized collections.
def copyToArray[B >: A](xs: Array[B], start: Int): Int
Copy elements to an array, returning the number of elements written.
Copy elements to an array, returning the number of elements written.
Fills the given array xs starting at index start with values of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.
B
the type of the elements of the array.
xs
the array to fill.
start
the starting index of xs.
returns
the number of elements written to the array Note: will not terminate for infinite-sized collections.
Definition Classes
IterableOnceOps
def copyToArray[B >: A](xs: Array[B]): Int
Copy elements to an array, returning the number of elements written.
Copy elements to an array, returning the number of elements written.
Fills the given array xs starting at index start with values of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.
B
the type of the elements of the array.
xs
the array to fill.
returns
the number of elements written to the array Note: will not terminate for infinite-sized collections.
Definition Classes
IterableOnceOps
def corresponds[B](that: collection.Seq[B])(p: (A, B) => Boolean): Boolean
Tests whether every element of this sequence relates to the corresponding element of another sequence by satisfying a test predicate.
Tests whether every element of this 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 and p(x, y) is true for all corresponding elements x of this sequence and y of that, otherwise false.
Definition Classes
SeqOps
def corresponds[B](that: IterableOnce[B])(p: (A, B) => Boolean): Boolean
Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.
Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.
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 and p(x, y) is true for all corresponding elements x of this iterator and y of that, otherwise false
Definition Classes
IterableOnceOps
def count(p: (A) => Boolean): Int
Counts the number of elements in the collection which satisfy a predicate.
Counts the number of elements in the collection which satisfy a predicate.
Note: will not terminate for infinite-sized collections.
p
the predicate used to test elements.
returns
the number of elements satisfying the predicate p.
Definition Classes
IterableOnceOps
def diff[B >: A](that: collection.Seq[B]): LazyList[A]
Computes the multiset difference between this lazy list and another sequence.
Computes the multiset difference between this lazy list and another sequence.
This method preserves laziness; elements are only evaluated individually as needed.
that
the sequence of elements to remove
returns
a new lazy list which contains all elements of this lazy list except some of occurrences of elements that also appear in that. If an element value x appears n times in that, then the first n occurrences of x will not form part of the result, but any following occurrences will.
Definition Classes
LazyList → SeqOps
def distinct: LazyList[A]
Selects all the elements of this sequence ignoring the duplicates.
Selects all the elements of this sequence ignoring the duplicates.
returns
a new sequence consisting of all the elements of this sequence without duplicates.
Definition Classes
SeqOps
def distinctBy[B](f: (A) => B): LazyList[A]
Selects all the elements of this sequence ignoring the duplicates as determined by == after applying the transforming function f.
Selects all the elements of this sequence ignoring the duplicates as determined by == after applying the transforming function f.
B
the type of the elements after being transformed by f
f
The transforming function whose result is used to determine the uniqueness of each element
returns
a new sequence consisting of all the elements of this sequence without duplicates.
Definition Classes
SeqOps
def drop(n: Int): LazyList[A]
Selects all elements except first n ones.
Selects all elements except first n ones.
This method does not evaluate anything until an operation is performed on the result (e.g. calling head or tail, or checking if it is empty). Additionally, it preserves laziness for all except the first n elements.
n
the number of elements to drop from this lazy list.
returns
a lazy list consisting of all elements of this lazy list except the first n ones, or else the empty lazy list, if this lazy list has less than n elements. If n is negative, don't drop any elements.
Definition Classes
LazyList → IterableOps → IterableOnceOps
def dropRight(n: Int): LazyList[A]
Selects all elements except last n ones.
Selects all elements except last n ones.
This method does not evaluate anything until an operation is performed on the result (e.g. calling head or tail, or checking if it is empty).
n
the number of elements to drop from this lazy list.
returns
a lazy list consisting of all elements of this lazy list except the last n ones, or else the empty lazy list, if this lazy list has less than n elements. If n is negative, don't drop any elements.
Definition Classes
LazyList → IterableOps
def dropWhile(p: (A) => Boolean): LazyList[A]
Drops longest prefix of elements that satisfy a predicate.
Drops longest prefix of elements that satisfy a predicate.
This method does not evaluate anything until an operation is performed on the result (e.g. calling head or tail, or checking if it is empty). Additionally, it preserves laziness for all elements after the predicate returns false.
p
The predicate used to test elements.
returns
the longest suffix of this lazy list whose first element does not satisfy the predicate p.
Definition Classes
LazyList → IterableOps → IterableOnceOps
def elementWise: ElementWiseExtractor[Int, A]
Returns an extractor object with a unapplySeq method, which extracts each element of a sequence data.
Returns an extractor object with a unapplySeq method, which extracts each element of a sequence data.
Definition Classes
PartialFunction
Example:
1. val firstChar: String => Option[Char] = _.headOption Seq("foo", "bar", "baz") match { case firstChar.unlift.elementWise(c0, c1, c2) => println(s"$c0, $c1, $c2") // Output: f, b, b }
def empty: LazyList[A]
The empty iterable of the same type as this iterable
The empty iterable of the same type as this iterable
returns
an empty iterable of type C.
Definition Classes
IterableFactoryDefaults → IterableOps
def endsWith[B >: A](that: collection.Iterable[B]): Boolean
Tests whether this sequence ends with the given sequence.
Tests whether this sequence ends with the given sequence.
Note: will not terminate for infinite-sized collections.
that
the sequence to test
returns
true if this sequence has that as a suffix, false otherwise.
Definition Classes
SeqOps
def ensuring(cond: (LazyList[A]) => Boolean, msg: => Any): LazyList[A]
Implicit
This member is added by an implicit conversion from LazyList[A] toEnsuring[LazyList[A]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: (LazyList[A]) => Boolean): LazyList[A]
Implicit
This member is added by an implicit conversion from LazyList[A] toEnsuring[LazyList[A]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: Boolean, msg: => Any): LazyList[A]
Implicit
This member is added by an implicit conversion from LazyList[A] toEnsuring[LazyList[A]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: Boolean): LazyList[A]
Implicit
This member is added by an implicit conversion from LazyList[A] toEnsuring[LazyList[A]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
final def eq(arg0: AnyRef): Boolean
Tests whether the argument (that) is a reference to the receiver object (this).
Tests whether the argument (that) is a reference to the receiver object (this).
The eq method implements an equivalence relation on non-null instances of AnyRef, and has three additional properties:
- It is consistent: for any non-null instances x and y of type AnyRef, multiple invocations of x.eq(y) consistently returns true or consistently returns false.
- For any non-null instance x of type AnyRef, x.eq(null) and null.eq(x) returns false.
- null.eq(null) returns true.
When overriding the equals or hashCode methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2), they should be equal to each other (o1 == o2) and they should hash to the same value (o1.hashCode == o2.hashCode).
returns
true if the argument is a reference to the receiver object; false otherwise.
Definition Classes
AnyRef
def equals(that: Any): Boolean
The universal equality method defined in AnyRef.
The universal equality method defined in AnyRef.
This method evaluates all elements of the collection.
Definition Classes
LazyList → Seq → Equals → AnyRef → Any
def exists(p: (A) => Boolean): Boolean
Tests whether a predicate holds for at least one element of this sequence.
Tests whether a predicate holds for at least one element of this sequence.
Note: may not terminate for infinite-sized collections.
p
the predicate used to test elements.
returns
true if the given predicate p is satisfied by at least one element of this sequence, otherwise false
Definition Classes
LinearSeqOps → IterableOnceOps
def filter(pred: (A) => Boolean): LazyList[A]
Selects all elements of this lazy list which satisfy a predicate.
Selects all elements of this lazy list which satisfy a predicate.
This method preserves laziness; elements are only evaluated individually as needed.
returns
a new iterator consisting of all elements of this lazy list that satisfy the given predicate p. The order of the elements is preserved.
Definition Classes
LazyList → IterableOps → IterableOnceOps
def filterNot(pred: (A) => Boolean): LazyList[A]
Selects all elements of this lazy list which do not satisfy a predicate.
Selects all elements of this lazy list which do not satisfy a predicate.
This method preserves laziness; elements are only evaluated individually as needed.
pred
the predicate used to test elements.
returns
a new lazy list consisting of all elements of this lazy list that do not satisfy the given predicate pred. Their order may not be preserved.
Definition Classes
LazyList → IterableOps → IterableOnceOps
def finalize(): Unit
Called by the garbage collector on the receiver object when there are no more references to the object.
Called by the garbage collector on the receiver object when there are no more references to the object.
The details of when and if the finalize method is invoked, as well as the interaction between finalize and non-local returns and exceptions, are all platform dependent.
Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.Throwable])
Note
not specified by SLS as a member of AnyRef
def find(p: (A) => Boolean): Option[A]
Finds the first element of the lazy list satisfying a predicate, if any.
Finds the first element of the lazy list satisfying a predicate, if any.
Note: may not terminate for infinite-sized collections.
This method does not evaluate any elements further than the first element matching the predicate.
p
the predicate used to test elements.
returns
an option value containing the first element in the lazy list that satisfies p, or None if none exists.
Definition Classes
LazyList → LinearSeqOps → IterableOnceOps
Annotations
@tailrec()
def findLast(p: (A) => Boolean): Option[A]
Finds the last element of the sequence satisfying a predicate, if any.
Finds the last element of the 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 sequence that satisfies p, or None if none exists.
Definition Classes
LinearSeqOps → SeqOps
def flatMap[B](f: (A) => IterableOnce[B]): LazyList[B]
Builds a new lazy list by applying a function to all elements of this lazy list and using the elements of the resulting collections.
Builds a new lazy list by applying a function to all elements of this lazy list and using the elements of the resulting collections.
For example:
```
def getWords(lines: Seq[String]): Seq[String] = lines flatMap (line => line split "\\W+")
```
The type of the resulting collection is guided by the static type of lazy list. This might cause unexpected results sometimes. For example:
```
// lettersOf will return a Seq[Char] of likely repeated letters, instead of a Set
def lettersOf(words: Seq[String]) = words flatMap (word => word.toSet)

// lettersOf will return a Set[Char], not a Seq
def lettersOf(words: Seq[String]) = words.toSet flatMap ((word: String) => word.toSeq)

// xs will be an Iterable[Int]
val xs = Map("a" -> List(11,111), "b" -> List(22,222)).flatMap(_._2)

// ys will be a Map[Int, Int]
val ys = Map("a" -> List(1 -> 11,1 -> 111), "b" -> List(2 -> 22,2 -> 222)).flatMap(_._2)
```
This method preserves laziness; elements are only evaluated individually as needed.
B
the element type of the returned collection.
f
the function to apply to each element.
returns
a new lazy list resulting from applying the given collection-valued function f to each element of this lazy list and concatenating the results.
Definition Classes
LazyList → IterableOps → IterableOnceOps
def flatten[B](implicit asIterable: (A) => IterableOnce[B]): LazyList[B]
Converts this lazy list of traversable collections into a lazy list formed by the elements of these traversable collections.
Converts this lazy list of traversable collections into a lazy list formed by the elements of these traversable collections.
The resulting collection's type will be guided by the type of lazy list. For example:
```
val xs = List(
           Set(1, 2, 3),
           Set(1, 2, 3)
         ).flatten
// xs == List(1, 2, 3, 1, 2, 3)

val ys = Set(
           List(1, 2, 3),
           List(3, 2, 1)
         ).flatten
// ys == Set(1, 2, 3)
```
This method preserves laziness; elements are only evaluated individually as needed.
B
the type of the elements of each traversable collection.
asIterable
an implicit conversion which asserts that the element type of this lazy list is a GenTraversable.
returns
a new lazy list resulting from concatenating all element lazy lists.
Definition Classes
LazyList → IterableOps → IterableOnceOps
def fold[A1 >: A](z: A1)(op: (A1, A1) => A1): A1
Folds the elements of this collection using the specified associative binary operator.
Folds the elements of this collection using the specified associative binary operator. The default implementation in IterableOnce is equivalent to foldLeft but may be overridden for more efficient traversal orders.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
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 and z, or z if this collection is empty.
Definition Classes
IterableOnceOps
def foldLeft[B](z: B)(op: (B, A) => B): B
LazyList specialization of foldLeft which allows GC to collect along the way.
LazyList 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 LazyList.
returns
The accumulated value from successive applications of op.
Definition Classes
LazyList → LinearSeqOps → IterableOnceOps
Annotations
@tailrec()
def foldRight[B](z: B)(op: (A, B) => B): B
Applies a binary operator to all elements of this collection and a start value, going right to left.
Applies a binary operator to all elements of this 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 collection, going right to left with the start value z on the right:
```
op(x_1, op(x_2, ... op(x_n, z)...))
```
where x₁, ..., x_n are the elements of this collection. Returns z if this collection is empty.
Definition Classes
IterableOnceOps
def forall(p: (A) => Boolean): Boolean
Tests whether a predicate holds for all elements of this sequence.
Tests whether a predicate holds for all elements of this sequence.
Note: may not terminate for infinite-sized collections.
p
the predicate used to test elements.
returns
true if this sequence is empty or the given predicate p holds for all elements of this sequence, otherwise false.
Definition Classes
LinearSeqOps → IterableOnceOps
def force: LazyList.this.type
Evaluates all undefined elements of the lazy list.
Evaluates all undefined elements of the lazy list.
This method detects cycles in lazy lists, and terminates after all elements of the cycle are evaluated. For example:
```
val ring: LazyList[Int] = 1 #:: 2 #:: 3 #:: ring
ring.force
ring.toString

// prints
//
// LazyList(1, 2, 3, ...)
```
This method will *not* terminate for non-cyclic infinite-sized collections.
returns
this
def foreach[U](f: (A) => 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
LazyList → 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 LazyList as elements are consumed.
,
This function will force the realization of the entire LazyList unless the f throws an exception.
def formatted(fmtstr: String): String
Returns string formatted according to given format string.
Returns string formatted according to given format string. Format strings are as for String.format (@see java.lang.String.format).
Implicit
This member is added by an implicit conversion from LazyList[A] toStringFormat[LazyList[A]] performed by method StringFormat in scala.Predef.
Definition Classes
StringFormat
Annotations
@inline()
def fromSpecific(coll: IterableOnce[A]): LazyList[A]
Defines how to turn a given Iterable[A] into a collection of type C.
Defines how to turn a given Iterable[A] into a collection of type C.
This process can be done in a strict way or a non-strict way (ie. without evaluating the elements of the resulting collections). In other words, this methods defines the evaluation model of the collection.
Attributes
protected
Definition Classes
IterableFactoryDefaults → IterableOps
Note
When implementing a custom collection type and refining C to the new type, this method needs to be overridden (the compiler will issue an error otherwise). In the common case where C =:= CC[A], this can be done by mixing in the scala.collection.IterableFactoryDefaults trait, which implements the method using iterableFactory.
,
As witnessed by the @uncheckedVariance annotation, using this method might be unsound. However, as long as it is called with an Iterable[A] obtained from this collection (as it is the case in the implementations of operations where we use a View[A]), it is safe.
final def getClass(): Class[_ <: AnyRef]
Returns the runtime class representation of the object.
Returns the runtime class representation of the object.
returns
a class object corresponding to the runtime type of the receiver.
Definition Classes
AnyRef → Any
Annotations
@native()
def groupBy[K](f: (A) => K): Map[K, LazyList[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: Even when applied to a view or a lazy collection it will always force the elements.
K
the type of keys returned by the discriminator function.
f
the discriminator function.
returns
A map from keys to iterable collections such that the following invariant holds:
```
(xs groupBy f)(k) = xs filter (x => f(x) == k)
```
That is, every key k is bound to a iterable collection of those elements x for which f(x) equals k.
Definition Classes
IterableOps
def groupMap[K, B](key: (A) => K)(f: (A) => B): Map[K, LazyList[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 type B using the value function.
It is equivalent to groupBy(key).mapValues(_.map(f)), but more efficient.
```
case class User(name: String, age: Int)

def namesByAge(users: Seq[User]): Map[Int, Seq[String]] =
  users.groupMap(_.age)(_.name)
```
Note: Even when applied to a view or a lazy collection it will always force the elements.
K
the type of keys returned by the discriminator function
B
the type of values returned by the transformation function
key
the discriminator function
f
the element transformation function
Definition Classes
IterableOps
def groupMapReduce[K, B](key: (A) => K)(f: (A) => B)(reduce: (B, B) => B): Map[K, B]
Partitions this 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 the value function and then reduced into a single value with the reduce function.
It is equivalent to groupBy(key).mapValues(_.map(f).reduce(reduce)), but more efficient.
```
def occurrences[A](as: Seq[A]): Map[A, Int] =
  as.groupMapReduce(identity)(_ => 1)(_ + _)
```
Note: Even when applied to a view or a lazy collection it will always force the elements.
Definition Classes
IterableOps
def grouped(size: Int): Iterator[LazyList[A]]
Partitions elements in fixed size lazy lists.
Partitions elements in fixed size lazy lists.
The iterator returned by this method mostly preserves laziness; a single element ahead of the iterator is evaluated.
size
the number of elements per group
returns
An iterator producing lazy lists of size size, except the last will be less than size size if the elements don't divide evenly.
Definition Classes
LazyList → IterableOps
def hashCode(): Int
The hashCode method for reference types.
The hashCode method for reference types. See hashCode in scala.Any.
returns
the hash code value for this object.
Definition Classes
Seq → AnyRef → Any
def head: A
Selects the first element of this lazy list.
Selects the first element of this lazy list.
returns
the first element of this lazy list.
Definition Classes
LazyList → LinearSeqOps → IterableOps
Exceptions thrown
NoSuchElementException if the lazy list is empty.
def headOption: Option[A]
Optionally selects the first element.
Optionally selects the first element.
returns
the first element of this sequence if it is nonempty, None if it is empty.
Definition Classes
LinearSeqOps → IterableOps
def indexOf[B >: A](elem: B): Int
Finds index of first occurrence of some value in this sequence.
Finds index of first occurrence of some value in this 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 sequence that is equal (as determined by ==) to elem, or -1, if none exists.
Definition Classes
SeqOps
Annotations
@deprecatedOverriding(message = "Override indexOf(elem, from) instead - indexOf(elem) calls indexOf(elem, 0)", since = "2.13.0")
def indexOf[B >: A](elem: B, from: Int): Int
Finds index of first occurrence of some value in this sequence after or at some start index.
Finds index of first occurrence of some value in this 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 sequence that is equal (as determined by ==) to elem, or -1, if none exists.
Definition Classes
SeqOps
def indexOfSlice[B >: A](that: collection.Seq[B]): Int
Finds first index where this sequence contains a given sequence as a slice.
Finds first index where this 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 sequence starting at this index match the elements of sequence that, or -1 of no such subsequence exists.
Definition Classes
SeqOps
Annotations
@deprecatedOverriding(message = "Override indexOfSlice(that, from) instead - indexOfSlice(that) calls indexOfSlice(that, 0)", since = "2.13.0")
def indexOfSlice[B >: A](that: collection.Seq[B], from: Int): Int
Finds first index after or at a start index where this sequence contains a given sequence as a slice.
Finds first index after or at a start index where this 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 sequence starting at this index match the elements of sequence that, or -1 of no such subsequence exists.
Definition Classes
SeqOps
def indexWhere(p: (A) => Boolean, from: Int): Int
Finds index of the first element satisfying some predicate after or at some start index.
Finds index of the first element satisfying some predicate after or at some start index.
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 sequence that satisfies the predicate p, or -1, if none exists.
Definition Classes
LinearSeqOps → SeqOps
def indexWhere(p: (A) => Boolean): Int
Finds index of the first element satisfying some predicate.
Finds index of the first element satisfying some predicate.
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 sequence that satisfies the predicate p, or -1, if none exists.
Definition Classes
SeqOps
Annotations
@deprecatedOverriding(message = "Override indexWhere(p, from) instead - indexWhere(p) calls indexWhere(p, 0)", since = "2.13.0")
def indices: Range
Produces the range of all indices of this sequence.
Produces the range of all indices of this sequence.
Note: Even when applied to a view or a lazy collection it will always force the elements.
returns
a Range value from 0 to one less than the length of this sequence.
Definition Classes
SeqOps
def init: LazyList[A]
The initial part of the collection without its last element.
The initial part of the collection without its last element.
Note: Even when applied to a view or a lazy collection it will always force the elements.
Definition Classes
IterableOps
def inits: Iterator[LazyList[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.
Note: Even when applied to a view or a lazy collection it will always force the elements.
returns
an iterator over all the inits of this iterable collection
Definition Classes
IterableOps
Example:
1. List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)
def intersect[B >: A](that: collection.Seq[B]): LazyList[A]
Computes the multiset intersection between this lazy list and another sequence.
Computes the multiset intersection between this lazy list and another sequence.
This method preserves laziness; elements are only evaluated individually as needed.
that
the sequence of elements to intersect with.
returns
a new lazy list which contains all elements of this lazy list which also appear in that. If an element value x appears n times in that, then the first n occurrences of x will be retained in the result, but any following occurrences will be omitted.
Definition Classes
LazyList → SeqOps
def isDefinedAt(x: Int): Boolean
Tests whether this sequence contains given index.
Tests whether this sequence contains given index.
The implementations of methods apply and isDefinedAt turn a Seq[A] into a PartialFunction[Int, A].
returns
true if this sequence contains an element at position idx, false otherwise.
Definition Classes
LinearSeqOps → SeqOps
def isEmpty: Boolean
Tests whether the lazy list is empty.
Tests whether the lazy list 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 lazy list contains no elements, false otherwise.
Definition Classes
LazyList → LinearSeqOps → SeqOps → IterableOnceOps
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 return false, while the expression List(1).isInstanceOf[List[String]] will return true. 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 type T0; false otherwise.
Definition Classes
Any
def isTraversableAgain: Boolean
Tests whether this iterable collection can be repeatedly traversed.
Tests whether this iterable collection can be repeatedly traversed. Always true for Iterables and false for Iterators unless overridden.
returns
true if it is repeatedly traversable, false otherwise.
Definition Classes
IterableOps → IterableOnceOps
def iterableFactory: SeqFactory[LazyList]
The companion object of this lazy list, providing various factory methods.
The companion object of this lazy list, providing various factory methods.
Definition Classes
LazyList → LinearSeq → LinearSeq → Seq → Iterable → Seq → Iterable → IterableOps
Note
When implementing a custom collection type and refining CC to the new type, this method needs to be overridden to return a factory for the new type (the compiler will issue an error otherwise).
def iterator: Iterator[A]
Iterator can be used only once
Iterator can be used only once
The iterator returned by this method preserves laziness; elements are only evaluated individually as needed.
Definition Classes
LazyList → LinearSeqOps → IterableOnce
def knownSize: Int
This method preserves laziness; elements are only evaluated individually as needed.
This method preserves laziness; elements are only evaluated individually as needed.
returns
The number of elements in this lazy list, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.
Definition Classes
LazyList → IterableOnce
def last: A
Selects the last element.
Selects the last element.
returns
The last element of this sequence.
Definition Classes
LinearSeqOps → IterableOps
Exceptions thrown
NoSuchElementException If the sequence is empty.
def lastIndexOf[B >: A](elem: B, end: Int = length - 1): Int
Finds index of last occurrence of some value in this sequence before or at a given end index.
Finds index of last occurrence of some value in this 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 sequence that is equal (as determined by ==) to elem, or -1, if none exists.
Definition Classes
SeqOps
def lastIndexOfSlice[B >: A](that: collection.Seq[B]): Int
Finds last index where this sequence contains a given sequence as a slice.
Finds last index where this 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 sequence starting at this index match the elements of sequence that, or -1 of no such subsequence exists.
Definition Classes
SeqOps
Annotations
@deprecatedOverriding(message = "Override lastIndexOfSlice(that, end) instead - lastIndexOfSlice(that) calls lastIndexOfSlice(that, Int.MaxValue)", since = "2.13.0")
def lastIndexOfSlice[B >: A](that: collection.Seq[B], end: Int): Int
Finds last index before or at a given end index where this sequence contains a given sequence as a slice.
Finds last index before or at a given end index where this 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 sequence starting at this index match the elements of sequence that, or -1 of no such subsequence exists.
Definition Classes
SeqOps
def lastIndexWhere(p: (A) => Boolean, end: Int): Int
Finds index of last element satisfying some predicate before or at given end index.
Finds index of last element satisfying some predicate before or at given end index.
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 sequence that satisfies the predicate p, or -1, if none exists.
Definition Classes
LinearSeqOps → SeqOps
def lastIndexWhere(p: (A) => Boolean): Int
Finds index of last element satisfying some predicate.
Finds index of last element satisfying some predicate.
Note: will not terminate for infinite-sized collections.
p
the predicate used to test elements.
returns
the index of the last element of this sequence that satisfies the predicate p, or -1, if none exists.
Definition Classes
SeqOps
Annotations
@deprecatedOverriding(message = "Override lastIndexWhere(p, end) instead - lastIndexWhere(p) calls lastIndexWhere(p, Int.MaxValue)", since = "2.13.0")
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.
Definition Classes
IterableOps
def lazyAppendedAll[B >: A](suffix: => IterableOnce[B]): LazyList[B]
The lazy list resulting from the concatenation of this lazy list with the argument lazy list.
The lazy list resulting from the concatenation of this lazy list with the argument lazy list.
This method preserves laziness; elements are only evaluated individually as needed.
Note: Repeated chaining of calls to append methods (appended, appendedAll, lazyAppendedAll) without forcing any of the intermediate resulting lazy lists may overflow the stack when the final result is forced.
suffix
The collection that gets appended to this lazy list
returns
The lazy list containing elements of this lazy list and the iterable object.
def lazyZip[B](that: collection.Iterable[B]): LazyZip2[A, B, LazyList.this.type]
Analogous to zip except that the elements in each collection are not consumed until a strict operation is invoked on the returned LazyZip2 decorator.
Analogous to zip except that the elements in each collection are not consumed until a strict operation is invoked on the returned LazyZip2 decorator.
Calls to lazyZip can be chained to support higher arities (up to 4) without incurring the expense of constructing and deconstructing intermediary tuples.
```
val xs = List(1, 2, 3)
val res = (xs lazyZip xs lazyZip xs lazyZip xs).map((a, b, c, d) => a + b + c + d)
// res == List(4, 8, 12)
```
This method is not particularly useful for a lazy list, as zip already preserves laziness.
The collection.LazyZip2 returned by this method preserves laziness; elements are only evaluated individually as needed.
B
the type of the second element in each eventual pair
that
the iterable providing the second element of each eventual pair
returns
a decorator LazyZip2 that allows strict operations to be performed on the lazily evaluated pairs or chained calls to lazyZip. Implicit conversion to Iterable[(A, B)] is also supported.
Definition Classes
LazyList → Iterable
def length: Int
The length (number of elements) of the sequence.
The length (number of elements) of the sequence. size is an alias for length in Seq collections.
Definition Classes
LinearSeqOps → SeqOps
def lengthCompare(that: collection.Iterable[_]): Int
Compares the length of this sequence to the size of another Iterable.
Compares the length of this sequence to the size of another Iterable.
that
the Iterable whose size is compared with this sequence's length.
returns
A value x where
```
x <  0       if this.length <  that.size
x == 0       if this.length == that.size
x >  0       if this.length >  that.size
```
The method as implemented here does not call length or size directly; its running time is O(this.length min that.size) instead of O(this.length + that.size). The method should be overridden if computing size is cheap and knownSize returns -1.
Definition Classes
LinearSeqOps → SeqOps
def lengthCompare(len: Int): Int
Compares the length of this sequence to a test value.
Compares the length of this sequence to a test value.
len
the test value that gets compared with the length.
returns
A value x where
```
x <  0       if this.length <  len
x == 0       if this.length == len
x >  0       if this.length >  len
```
The method as implemented here does not call length directly; its running time is O(length min len) instead of O(length). The method should be overridden if computing length is cheap and knownSize returns -1.
Definition Classes
LinearSeqOps → SeqOps
See also
lengthIs
final def lengthIs: SizeCompareOps
Returns a value class containing operations for comparing the length of this sequence to a test value.
Returns a value class containing operations for comparing the length of this 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
```
Definition Classes
SeqOps
Annotations
@inline()
def lift: (Int) => Option[A]
Turns this partial function into a plain function returning an Option result.
Turns this partial function into a plain function returning an Option result.
returns
a function that takes an argument x to Some(this(x)) if this is defined for x, and to None otherwise.
Definition Classes
PartialFunction
See also
Function.unlift
def map[B](f: (A) => B): LazyList[B]
Builds a new lazy list by applying a function to all elements of this lazy list.
Builds a new lazy list by applying a function to all elements of this lazy list.
This method preserves laziness; elements are only evaluated individually as needed.
B
the element type of the returned lazy list.
f
the function to apply to each element.
returns
a new lazy list resulting from applying the given function f to each element of this lazy list and collecting the results.
Definition Classes
LazyList → IterableOps → IterableOnceOps
def max[B >: A](implicit ord: math.Ordering[B]): A
Finds the largest element.
Finds the largest element.
Note: will not terminate for infinite-sized collections.
B
The type over which the ordering is defined.
ord
An ordering to be used for comparing elements.
returns
the largest element of this collection with respect to the ordering ord.
Definition Classes
IterableOnceOps
Exceptions thrown
UnsupportedOperationException if this collection is empty.
def maxBy[B](f: (A) => B)(implicit cmp: math.Ordering[B]): A
Finds the first element which yields the largest value measured by function f.
Finds the first element which yields the largest value measured by function f.
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 collection with the largest value measured by function f with respect to the ordering cmp.
Definition Classes
IterableOnceOps
Exceptions thrown
UnsupportedOperationException if this collection is empty.
def maxByOption[B](f: (A) => B)(implicit cmp: math.Ordering[B]): Option[A]
Finds the first element which yields the largest value measured by function f.
Finds the first element which yields the largest value measured by function f.
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 collection with the largest value measured by function f with respect to the ordering cmp.
Definition Classes
IterableOnceOps
def maxOption[B >: A](implicit ord: math.Ordering[B]): Option[A]
Finds the largest element.
Finds the largest element.
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 collection with respect to the ordering ord.
Definition Classes
IterableOnceOps
def min[B >: A](implicit ord: math.Ordering[B]): A
Finds the smallest element.
Finds the smallest element.
Note: will not terminate for infinite-sized collections.
B
The type over which the ordering is defined.
ord
An ordering to be used for comparing elements.
returns
the smallest element of this collection with respect to the ordering ord.
Definition Classes
IterableOnceOps
Exceptions thrown
UnsupportedOperationException if this collection is empty.
def minBy[B](f: (A) => B)(implicit cmp: math.Ordering[B]): A
Finds the first element which yields the smallest value measured by function f.
Finds the first element which yields the smallest value measured by function f.
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 collection with the smallest value measured by function f with respect to the ordering cmp.
Definition Classes
IterableOnceOps
Exceptions thrown
UnsupportedOperationException if this collection is empty.
def minByOption[B](f: (A) => B)(implicit cmp: math.Ordering[B]): Option[A]
Finds the first element which yields the smallest value measured by function f.
Finds the first element which yields the smallest value measured by function f.
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 collection with the smallest value measured by function f with respect to the ordering cmp.
Definition Classes
IterableOnceOps
def minOption[B >: A](implicit ord: math.Ordering[B]): Option[A]
Finds the smallest element.
Finds the smallest element.
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 collection with respect to the ordering ord.
Definition Classes
IterableOnceOps
final def mkString: String
Displays all elements of this collection in a string.
Displays all elements of this collection in a string.
Delegates to addString, which can be overridden.
returns
a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this collection follow each other without any separator string.
Definition Classes
IterableOnceOps
Annotations
@inline()
final def mkString(sep: String): String
Displays all elements of this collection in a string using a separator string.
Displays all elements of this collection in a string using a separator string.
Delegates to addString, which can be overridden.
sep
the separator string.
returns
a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.
Definition Classes
IterableOnceOps
Annotations
@inline()
Example:
1. List(1, 2, 3).mkString("|") = "1|2|3"
final def mkString(start: String, sep: String, end: String): String
Displays all elements of this collection in a string using start, end, and separator strings.
Displays all elements of this collection in a string using start, end, and separator strings.
Delegates to addString, which can be overridden.
start
the starting string.
sep
the separator string.
end
the ending string.
returns
a string representation of this collection. The resulting string begins with the string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.
Definition Classes
IterableOnceOps
Example:
1. List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
final def ne(arg0: AnyRef): Boolean
Equivalent to !(this eq that).
Equivalent to !(this eq that).
returns
true if the argument is not a reference to the receiver object; false otherwise.
Definition Classes
AnyRef
def newSpecificBuilder: Builder[A, LazyList[A]]
returns
a strict builder for the same collection type. Note that in the case of lazy collections (e.g. scala.collection.View or scala.collection.immutable.LazyList), it is possible to implement this method but the resulting Builder will break laziness. As a consequence, operations should preferably be implemented with fromSpecific instead of this method.
Attributes
protected
Definition Classes
IterableFactoryDefaults → IterableOps
Note
When implementing a custom collection type and refining C to the new type, this method needs to be overridden (the compiler will issue an error otherwise). In the common case where C =:= CC[A], this can be done by mixing in the scala.collection.IterableFactoryDefaults trait, which implements the method using iterableFactory.
,
As witnessed by the @uncheckedVariance annotation, using this method might be unsound. However, as long as the returned builder is only fed with A values taken from this instance, it is safe.
def nonEmpty: Boolean
Tests whether the collection is not empty.
Tests whether the collection is not empty.
returns
true if the collection contains at least one element, false otherwise.
Definition Classes
IterableOnceOps
Annotations
@deprecatedOverriding(message = "nonEmpty is defined as !isEmpty; override isEmpty instead", since = "2.13.0")
final def notify(): Unit
Wakes up a single thread that is waiting on the receiver object's monitor.
Wakes up a single thread that is waiting on the receiver object's monitor.
Definition Classes
AnyRef
Annotations
@native()
Note
not specified by SLS as a member of AnyRef
final def notifyAll(): Unit
Wakes up all threads that are waiting on the receiver object's monitor.
Wakes up all threads that are waiting on the receiver object's monitor.
Definition Classes
AnyRef
Annotations
@native()
Note
not specified by SLS as a member of AnyRef
def occCounts[B](sq: collection.Seq[B]): mutable.Map[B, Int]
Attributes
protected[collection]
Definition Classes
SeqOps
def orElse[A1 <: Int, B1 >: A](that: PartialFunction[A1, B1]): PartialFunction[A1, B1]
Composes this partial function with a fallback partial function which gets applied where this partial function is not defined.
Composes this partial function with a fallback partial function which gets applied where this partial function is not defined.
A1
the argument type of the fallback function
B1
the result type of the fallback function
that
the fallback function
returns
a partial function which has as domain the union of the domains of this partial function and that. The resulting partial function takes x to this(x) where this is defined, and to that(x) where it is not.
Definition Classes
PartialFunction
def padTo[B >: A](len: Int, elem: B): LazyList[B]
A copy of this lazy list with an element value appended until a given target length is reached.
A copy of this lazy list with an element value appended until a given target length is reached.
This method preserves laziness; elements are only evaluated individually as needed.
B
the element type of the returned lazy list.
len
the target length
elem
the padding value
returns
a new lazy list consisting of all elements of this lazy list followed by the minimal number of occurrences of elem so that the resulting collection has a length of at least len.
Definition Classes
LazyList → SeqOps
def partition(p: (A) => Boolean): (LazyList[A], LazyList[A])
A pair of, first, all elements that satisfy predicate p and, second, all elements that do not.
A pair of, first, all elements that satisfy predicate p and, second, all elements that do not. Interesting because it splits a collection in two.
The default implementation provided here needs to traverse the collection twice. Strict collections have an overridden version of partition in StrictOptimizedIterableOps, which requires only a single traversal.
This method preserves laziness; elements are only evaluated individually as needed.
Definition Classes
LazyList → IterableOps
def partitionMap[A1, A2](f: (A) => Either[A1, A2]): (LazyList[A1], LazyList[A2])
Applies a function f to each element of the lazy list and returns a pair of lazy lists: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.
Applies a function f to each element of the lazy list and returns a pair of lazy lists: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.
Example:
```
val xs = `LazyList`(1, "one", 2, "two", 3, "three") partitionMap {
 case i: Int => Left(i)
 case s: String => Right(s)
}
// xs == (`LazyList`(1, 2, 3),
//        `LazyList`(one, two, three))
```
This method preserves laziness; elements are only evaluated individually as needed.
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 lazy list to an scala.util.Either
returns
a pair of lazy lists: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.
Definition Classes
LazyList → IterableOps
def patch[B >: A](from: Int, other: IterableOnce[B], replaced: Int): LazyList[B]
Produces a new lazy list where a slice of elements in this lazy list is replaced by another sequence.
Produces a new lazy list where a slice of elements in this lazy list is replaced by another sequence.
Patching at negative indices is the same as patching starting at 0. Patching at indices at or larger than the length of the original lazy list appends the patch to the end. If more values are replaced than actually exist, the excess is ignored.
This method preserves laziness; elements are only evaluated individually as needed.
B
the element type of the returned lazy list.
from
the index of the first replaced element
other
the replacement sequence
replaced
the number of elements to drop in the original lazy list
returns
a new lazy list consisting of all elements of this lazy list except that replaced elements starting from from are replaced by all the elements of other.
Definition Classes
LazyList → SeqOps
def permutations: Iterator[LazyList[A]]
Iterates over distinct permutations.
Iterates over distinct permutations.
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 sequence.
Definition Classes
SeqOps
Example:
1. "abb".permutations = Iterator(abb, bab, bba)
def prepended[B >: A](elem: B): LazyList[B]
A copy of the lazy list with an element prepended.
A copy of the lazy list with an element prepended.
Also, the original lazy list is not modified, so you will want to capture the result.
Example:
```
scala> val x = List(1)
x: List[Int] = List(1)

scala> val y = 2 +: x
y: List[Int] = List(2, 1)

scala> println(x)
List(1)
```
This method preserves laziness; elements are only evaluated individually as needed.
B
the element type of the returned lazy list.
elem
the prepended element
returns
a new lazy list consisting of value followed by all elements of this lazy list.
Definition Classes
LazyList → SeqOps
def prependedAll[B >: A](prefix: IterableOnce[B]): LazyList[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.
This method preserves laziness; elements are only evaluated individually as needed.
B
the element type of the returned collection.
prefix
the iterable to prepend.
returns
a new lazy list which contains all elements of prefix followed by all the elements of this lazy list.
Definition Classes
LazyList → SeqOps
def product[B >: A](implicit num: math.Numeric[B]): B
Multiplies up the elements of this collection.
Multiplies up the elements of this collection.
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 collection with respect to the * operator in num.
Definition Classes
IterableOnceOps
def reduce[B >: A](op: (B, B) => B): B
Reduces the elements of this collection using the specified associative binary operator.
Reduces the elements of this 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 collection is nonempty.
Definition Classes
IterableOnceOps
Exceptions thrown
UnsupportedOperationException if this collection is empty.
def reduceLeft[B >: A](f: (B, A) => B): B
LazyList specialization of reduceLeft which allows GC to collect along the way.
LazyList 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 LazyList.
returns
The accumulated value from successive applications of f.
Definition Classes
LazyList → IterableOnceOps
def reduceLeftOption[B >: A](op: (B, A) => B): Option[B]
Optionally applies a binary operator to all elements of this collection, going left to right.
Optionally applies a binary operator to all elements of this 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 collection is nonempty, None otherwise.
Definition Classes
IterableOnceOps
def reduceOption[B >: A](op: (B, B) => B): Option[B]
Reduces the elements of this collection, if any, using the specified associative binary operator.
Reduces the elements of this 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, and None otherwise.
Definition Classes
IterableOnceOps
def reduceRight[B >: A](op: (A, B) => B): B
Applies a binary operator to all elements of this collection, going right to left.
Applies a binary operator to all elements of this 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 collection, going right to left:
```
op(x_1, op(x_2, ..., op(x_{n-1}, x_n)...))
```
where x₁, ..., x_n are the elements of this collection.
Definition Classes
IterableOnceOps
Exceptions thrown
UnsupportedOperationException if this collection is empty.
def reduceRightOption[B >: A](op: (A, B) => B): Option[B]
Optionally applies a binary operator to all elements of this collection, going right to left.
Optionally applies a binary operator to all elements of this 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 collection is nonempty, None otherwise.
Definition Classes
IterableOnceOps
def reverse: LazyList[A]
Returns new lazy list with elements in reversed order.
Returns new lazy list 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.
This method evaluates all elements of the collection.
returns
A new lazy list with all elements of this lazy list in reversed order.
Definition Classes
LazyList → SeqOps
def reverseIterator: Iterator[A]
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 as xs.reverse.iterator but might be more efficient.
returns
an iterator yielding the elements of this sequence in reversed order
Definition Classes
SeqOps
def reversed: collection.Iterable[A]
Attributes
protected
Definition Classes
IterableOnceOps
def runWith[U](action: (A) => U): (Int) => Boolean
Composes this partial function with an action function which gets applied to results of this partial function.
Composes this partial function with an action function which gets applied to results of this partial function. The action function is invoked only for its side effects; its result is ignored.
Note that expression pf.runWith(action)(x) is equivalent to
```
if(pf isDefinedAt x) { action(pf(x)); true } else false
```
except that runWith is implemented via applyOrElse and thus potentially more efficient. Using runWith avoids double evaluation of pattern matchers and guards for partial function literals.
action
the action function
returns
a function which maps arguments x to isDefinedAt(x). The resulting function runs action(this(x)) where this is defined.
Definition Classes
PartialFunction
See also
applyOrElse.
def sameElements[B >: A](that: IterableOnce[B]): Boolean
Are the elements of this collection the same (and in the same order) as those of that?
Are the elements of this collection the same (and in the same order) as those of that?
Definition Classes
LinearSeqOps → SeqOps
def scan[B >: A](z: B)(op: (B, B) => B): LazyList[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
Definition Classes
IterableOps
def scanLeft[B](z: B)(op: (B, A) => B): LazyList[B]
Produces a lazy list containing cumulative results of applying the operator going left to right, including the initial value.
Produces a lazy list containing cumulative results of applying the operator going left to right, including the initial value.
Note: will not terminate for infinite-sized collections.
This method preserves laziness; elements are only evaluated individually as needed.
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
LazyList → IterableOps → IterableOnceOps
def scanRight[B](z: B)(op: (A, B) => B): LazyList[B]
Produces a collection containing cumulative results of applying the operator going right to left.
Produces a collection containing cumulative results of applying the operator going right to left. The head of the collection is the last cumulative result.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Note: Even when applied to a view or a lazy collection it will always force the elements.
Example:
```
List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)
```
B
the type of the elements in the resulting collection
z
the initial value
op
the binary operator applied to the intermediate result and the element
returns
collection with intermediate results
Definition Classes
IterableOps
def search[B >: A](elem: B, from: Int, to: Int)(implicit ord: Ordering[B]): SearchResult
Search within an interval in this sorted sequence for a specific element.
Search within an interval in this sorted sequence for a specific element. If this sequence is an IndexedSeq, a binary search is used. Otherwise, a linear search is used.
The sequence should be sorted with the same Ordering before calling; otherwise, the results are undefined.
elem
the element to find.
from
the index where the search starts.
to
the index following where the search ends.
ord
the ordering to be used to compare elements.
returns
a Found value containing the index corresponding to the element in the sequence, or the InsertionPoint where the element would be inserted if the element is not in the sequence.
Definition Classes
SeqOps
Note
if to <= from, the search space is empty, and an InsertionPoint at from is returned
See also
scala.collection.IndexedSeq
scala.math.Ordering
scala.collection.SeqOps, method sorted
def search[B >: A](elem: B)(implicit ord: Ordering[B]): SearchResult
Search this sorted sequence for a specific element.
Search this sorted sequence for a specific element. If the sequence is an IndexedSeq, a binary search is used. Otherwise, a linear search is used.
The sequence should be sorted with the same Ordering before calling; otherwise, the results are undefined.
elem
the element to find.
ord
the ordering to be used to compare elements.
returns
a Found value containing the index corresponding to the element in the sequence, or the InsertionPoint where the element would be inserted if the element is not in the sequence.
Definition Classes
SeqOps
See also
scala.collection.IndexedSeq
scala.math.Ordering
scala.collection.SeqOps, method sorted
def segmentLength(p: (A) => Boolean, from: Int): Int
Computes the length of the longest segment that starts from some index and whose elements all satisfy some predicate.
Computes the length of the longest segment that starts from some index and whose elements all satisfy some predicate.
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 sequence starting from index from such that every element of the segment satisfies the predicate p.
Definition Classes
LinearSeqOps → SeqOps
final def segmentLength(p: (A) => Boolean): Int
Computes the length of the longest segment that starts from the first element and whose elements all satisfy some predicate.
Computes the length of the longest segment that starts from the first element and whose elements all satisfy some predicate.
Note: may not terminate for infinite-sized collections.
p
the predicate used to test elements.
returns
the length of the longest segment of this 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 sequence.
The size of this sequence.
Note: will not terminate for infinite-sized collections.
returns
the number of elements in this sequence.
Definition Classes
SeqOps → IterableOnceOps
final def sizeCompare(that: collection.Iterable[_]): Int
Compares the size of this sequence to the size of another Iterable.
Compares the size of this sequence to the size of another Iterable.
that
the Iterable whose size is compared with this sequence's size.
returns
A value x where
```
x <  0       if this.size <  that.size
x == 0       if this.size == that.size
x >  0       if this.size >  that.size
```
The method as implemented here does not call size directly; its running time is O(this.size min that.size) instead of O(this.size + that.size). The method should be overridden if computing size is cheap and knownSize returns -1.
Definition Classes
SeqOps → IterableOps
final def sizeCompare(otherSize: Int): Int
Compares the size of this sequence to a test value.
Compares the size of this sequence to a test value.
otherSize
the test value that gets compared with the size.
returns
A value x where
```
x <  0       if this.size <  otherSize
x == 0       if this.size == otherSize
x >  0       if this.size >  otherSize
```
The method as implemented here does not call size directly; its running time is O(size min otherSize) instead of O(size). The method should be overridden if computing size is cheap and knownSize returns -1.
Definition Classes
SeqOps → IterableOps
See also
sizeIs
final def sizeIs: SizeCompareOps
Returns a value class containing operations for comparing the size of this iterable collection to a test value.
Returns a value class containing operations for comparing the size of this iterable collection to a test value.
These operations are implemented in terms of sizeCompare(Int), and allow the following more readable usages:
```
this.sizeIs < size     // this.sizeCompare(size) < 0
this.sizeIs <= size    // this.sizeCompare(size) <= 0
this.sizeIs == size    // this.sizeCompare(size) == 0
this.sizeIs != size    // this.sizeCompare(size) != 0
this.sizeIs >= size    // this.sizeCompare(size) >= 0
this.sizeIs > size     // this.sizeCompare(size) > 0
```
Definition Classes
IterableOps
Annotations
@inline()
def slice(from: Int, until: Int): LazyList[A]
Selects an interval of elements.
Selects an interval of elements. The returned lazy list is made up of all elements x which satisfy the invariant:
```
from <= indexOf(x) < until
```
This method does not evaluate anything until an operation is performed on the result (e.g. calling head or tail, or checking if it is empty). Additionally, it preserves laziness for all but the first from elements.
from
the lowest index to include from this lazy list.
until
the lowest index to EXCLUDE from this lazy list.
returns
a lazy list containing the elements greater than or equal to index from extending up to (but not including) index until of this lazy list.
Definition Classes
LazyList → IterableOps → IterableOnceOps
def sliding(size: Int, step: Int): Iterator[LazyList[A]]
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
The returned iterator will be empty when called on an empty collection. The last element the iterator produces may be smaller than the window size when the original collection isn't exhausted by the window before it and its last element isn't skipped by the step before it.
The iterator returned by this method mostly preserves laziness; size - step max 1 elements ahead of the iterator are evaluated.
size
the number of elements per group
step
the distance between the first elements of successive groups
returns
An iterator producing lazy lists of size size, except the last element (which may be the only element) will be smaller if there are fewer than size elements remaining to be grouped.
Definition Classes
LazyList → IterableOps
def sliding(size: Int): Iterator[LazyList[A]]
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
An empty collection returns an empty iterator, and a non-empty collection containing fewer elements than the window size returns an iterator that will produce the original collection as its only element.
size
the number of elements per group
returns
An iterator producing iterable collections of size size, except for a non-empty collection with less than size elements, which returns an iterator that produces the source collection itself as its only element.
Definition Classes
IterableOps
Examples:
1. List().sliding(2) = empty iterator
2. List(1).sliding(2) = Iterator(List(1))
3. List(1, 2).sliding(2) = Iterator(List(1, 2))
4. List(1, 2, 3).sliding(2) = Iterator(List(1, 2), List(2, 3))
See also
scala.collection.Iterator, method sliding
def sortBy[B](f: (A) => B)(implicit ord: Ordering[B]): LazyList[A]
Sorts this sequence according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.
Sorts this 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 ordering ord is defined.
f
the transformation function mapping elements to some other domain B.
ord
the ordering assumed on domain B.
returns
a sequence consisting of the elements of this sequence sorted according to the ordering where x < y if ord.lt(f(x), f(y)).
Definition Classes
SeqOps
Example:
1. val words = "The quick brown fox jumped over the lazy dog".split(' ') // this works because scala.Ordering will implicitly provide an Ordering[Tuple2[Int, Char]] words.sortBy(x => (x.length, x.head)) res0: Array[String] = Array(The, dog, fox, the, lazy, over, brown, quick, jumped)
See also
scala.math.Ordering
def sortWith(lt: (A, A) => Boolean): LazyList[A]
Sorts this sequence according to a comparison function.
Sorts this 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 sequence consisting of the elements of this sequence sorted according to the comparison function lt.
Definition Classes
SeqOps
Example:
1. List("Steve", "Tom", "John", "Bob").sortWith(_.compareTo(_) < 0) = List("Bob", "John", "Steve", "Tom")
def sorted[B >: A](implicit ord: Ordering[B]): LazyList[A]
Sorts this sequence according to an Ordering.
Sorts this 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 sequence consisting of the elements of this 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: (A) => Boolean): (LazyList[A], LazyList[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 predicate p does not cause any side-effects.
Note: might return different results for different runs, unless the underlying collection type is ordered.
p
the test predicate
returns
a pair consisting of the longest prefix of this iterable collection whose elements all satisfy p, and the rest of this iterable collection.
Definition Classes
IterableOps → IterableOnceOps
def splitAt(n: Int): (LazyList[A], LazyList[A])
Splits this iterable collection into a prefix/suffix pair at a given position.
Splits this iterable collection into a prefix/suffix pair at a given position.
Note: c splitAt n is equivalent to (but possibly more efficient than) (c take n, c drop n).
Note: might return different results for different runs, unless the underlying collection type is ordered.
n
the position at which to split.
returns
a pair of iterable collections consisting of the first n elements of this iterable collection, and the other elements.
Definition Classes
IterableOps → IterableOnceOps
def startsWith[B >: A](that: IterableOnce[B], offset: Int = 0): Boolean
Tests whether this sequence contains the given sequence at a given index.
Tests whether this sequence contains the given sequence at a given index.
Note: If the both the receiver object this and the argument that are infinite sequences this method may not terminate.
that
the sequence to test
offset
the index where the sequence is searched.
returns
true if the sequence that is contained in this sequence at index offset, otherwise false.
Definition Classes
SeqOps
def stepper[S <: Stepper[_]](implicit shape: StepperShape[A, S]): S
Returns a scala.collection.Stepper for the elements of this collection.
Returns a scala.collection.Stepper for the elements of this collection.
The Stepper enables creating a Java stream to operate on the collection, see scala.jdk.StreamConverters. For collections holding primitive values, the Stepper can be used as an iterator which doesn't box the elements.
The implicit scala.collection.StepperShape parameter defines the resulting Stepper type according to the element type of this collection.
- For collections of Int, Short, Byte or Char, an scala.collection.IntStepper is returned
- For collections of Double or Float, a scala.collection.DoubleStepper is returned
- For collections of Long a scala.collection.LongStepper is returned
- For any other element type, an scala.collection.AnyStepper is returned
Note that this method is overridden in subclasses and the return type is refined to S with EfficientSplit, for example scala.collection.IndexedSeqOps.stepper. For Steppers marked with scala.collection.Stepper.EfficientSplit, the converters in scala.jdk.StreamConverters allow creating parallel streams, whereas bare Steppers can be converted only to sequential streams.
Definition Classes
IterableOnce
def stringPrefix: String
Attributes
protected[this]
Definition Classes
LinearSeq → Seq → Iterable
def sum[B >: A](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 collection with respect to the + operator in num.
Definition Classes
IterableOnceOps
final def synchronized[T0](arg0: => T0): T0
Executes the code in body with an exclusive lock on this.
Executes the code in body with an exclusive lock on this.
returns
the result of body
Definition Classes
AnyRef
def tail: LazyList[A]
The rest of the collection without its first element.
The rest of the collection without its first element.
Definition Classes
LazyList → LinearSeqOps → IterableOps
def tails: Iterator[LazyList[A]]
Iterates over the tails of this sequence.
Iterates over the tails of this sequence. The first value will be this sequence and the final one will be an empty sequence, with the intervening values the results of successive applications of tail.
returns
an iterator over all the tails of this sequence
Definition Classes
LinearSeqOps → IterableOps
Example:
1. List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)
def take(n: Int): LazyList[A]
Selects the first n elements.
Selects the first n elements.
This method preserves laziness; elements are only evaluated individually as needed.
n
the number of elements to take from this lazy list.
returns
a lazy list consisting only of the first n elements of this lazy list, or else the whole lazy list, if it has less than n elements. If n is negative, returns an empty lazy list.
Definition Classes
LazyList → IterableOps → IterableOnceOps
def takeRight(n: Int): LazyList[A]
Selects the last n elements.
Selects the last n elements.
This method does not evaluate anything until an operation is performed on the result (e.g. calling head or tail, or checking if it is empty).
n
the number of elements to take from this lazy list.
returns
a lazy list consisting only of the last n elements of this lazy list, or else the whole lazy list, if it has less than n elements. If n is negative, returns an empty lazy list.
Definition Classes
LazyList → IterableOps
def takeWhile(p: (A) => Boolean): LazyList[A]
Takes longest prefix of elements that satisfy a predicate.
Takes longest prefix of elements that satisfy a predicate.
This method preserves laziness; elements are only evaluated individually as needed.
p
The predicate used to test elements.
returns
the longest prefix of this lazy list whose elements all satisfy the predicate p.
Definition Classes
LazyList → IterableOps → IterableOnceOps
def tapEach[U](f: (A) => U): LazyList[A]
Applies a side-effecting function to each element in this collection.
Applies a side-effecting function to each element in this collection. Strict collections will apply f to their elements immediately, while lazy collections like Views and LazyLists will only apply f on each element if and when that element is evaluated, and each time that element is evaluated.
This method preserves laziness; elements are only evaluated individually as needed.
U
the return type of f
f
a function to apply to each element in this lazy list
returns
The same logical collection as this
Definition Classes
LazyList → IterableOps → IterableOnceOps
def to[C1](factory: Factory[A, C1]): C1
Given a collection factory factory, convert this collection to the appropriate representation for the current element type A.
Given a collection factory factory, convert this collection to the appropriate representation for the current element type A. Example uses:
xs.to(List) xs.to(ArrayBuffer) xs.to(BitSet) // for xs: Iterable[Int]
Definition Classes
IterableOnceOps
def toArray[B >: A](implicit arg0: ClassTag[B]): Array[B]
Convert collection to array.
Convert collection to array.
Implementation note: DO NOT call Array.from from this method.
Definition Classes
IterableOnceOps
final def toBuffer[B >: A]: Buffer[B]
Definition Classes
IterableOnceOps
Annotations
@inline()
def toIndexedSeq: IndexedSeq[A]
Definition Classes
IterableOnceOps
final def toIterable: LazyList.this.type
returns
This collection as an Iterable[A]. No new collection will be built if this is already an Iterable[A].
Definition Classes
Iterable → IterableOps
def toList: List[A]
Definition Classes
IterableOnceOps
def toMap[K, V](implicit ev: <:<[A, (K, V)]): Map[K, V]
Definition Classes
IterableOnceOps
final def toSeq: LazyList.this.type
returns
This collection as a Seq[A]. This is equivalent to to(Seq) but might be faster.
Definition Classes
Seq → IterableOnceOps
def toSet[B >: A]: Set[B]
Definition Classes
IterableOnceOps
def toString(): String
This method preserves laziness; elements are only evaluated individually as needed.
This method preserves laziness; elements are only evaluated individually as needed.
returns
a string representation of this collection. An undefined state is represented with "<not computed>" and cycles are represented with "<cycle>" Examples:
- "LazyList(4, <not computed>)", a non-empty lazy list ;
- "LazyList(1, 2, 3, <not computed>)", a lazy list with at least three elements ;
- "LazyList(1, 2, 3, <cycle>)", an infinite lazy list that contains a cycle at the fourth element.
Definition Classes
LazyList → Seq → Function1 → Iterable → AnyRef → Any
def toVector: Vector[A]
Definition Classes
IterableOnceOps
def transpose[B](implicit asIterable: (A) => collection.Iterable[B]): LazyList[LazyList[B]]
Transposes this lazy list of iterable collections into a lazy list of lazy lists.
Transposes this lazy list of iterable collections into a lazy list of lazy lists.
The resulting collection's type will be guided by the static type of lazy list. For example:
```
val xs = List(
           Set(1, 2, 3),
           Set(4, 5, 6)).transpose
// xs == List(
//         List(1, 4),
//         List(2, 5),
//         List(3, 6))

val ys = Vector(
           List(1, 2, 3),
           List(4, 5, 6)).transpose
// ys == Vector(
//         Vector(1, 4),
//         Vector(2, 5),
//         Vector(3, 6))
```
Note: Even when applied to a view or a lazy collection it will always force the elements.
This method evaluates all elements of the collection.
B
the type of the elements of each iterable collection.
asIterable
an implicit conversion which asserts that the element type of this lazy list is an Iterable.
returns
a two-dimensional lazy list of lazy lists which has as nth row the nth column of this lazy list.
Definition Classes
LazyList → IterableOps
def unapply(a: Int): Option[A]
Tries to extract a B from an A in a pattern matching expression.
Tries to extract a B from an A in a pattern matching expression.
Definition Classes
PartialFunction
def unlift: PartialFunction[Int, B]
Converts an optional function to a partial function.
Converts an optional function to a partial function.
Implicit
This member is added by an implicit conversion from LazyList[A] toUnliftOps[Int, B] performed by method UnliftOps in scala.Function1.This conversion will take place only if A is a subclass of Option[B] (A <: Option[B]).
Definition Classes
UnliftOps
Example:
1. Unlike Function.unlift, this UnliftOps.unlift method can be used in extractors.
  val of: Int => Option[String] = { i => if (i == 2) { Some("matched by an optional function") } else { None } } util.Random.nextInt(4) match { case of.unlift(m) => // Convert an optional function to a pattern println(m) case _ => println("Not matched") }
def unzip[A1, A2](implicit asPair: (A) => (A1, A2)): (LazyList[A1], LazyList[A2])
Converts this lazy list of pairs into two collections of the first and second half of each pair.
Converts this lazy list of pairs into two collections of the first and second half of each pair.
```
val xs = `LazyList`(
           (1, "one"),
           (2, "two"),
           (3, "three")).unzip
// xs == (`LazyList`(1, 2, 3),
//        `LazyList`(one, two, three))
```
This method preserves laziness; elements are only evaluated individually as needed.
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 lazy list is a pair.
returns
a pair of lazy lists, containing the first, respectively second half of each element pair of this lazy list.
Definition Classes
LazyList → IterableOps
def unzip3[A1, A2, A3](implicit asTriple: (A) => (A1, A2, A3)): (LazyList[A1], LazyList[A2], LazyList[A3])
Converts this lazy list of triples into three collections of the first, second, and third element of each triple.
Converts this lazy list of triples into three collections of the first, second, and third element of each triple.
```
val xs = `LazyList`(
           (1, "one", '1'),
           (2, "two", '2'),
           (3, "three", '3')).unzip3
// xs == (`LazyList`(1, 2, 3),
//        `LazyList`(one, two, three),
//        `LazyList`(1, 2, 3))
```
This method preserves laziness; elements are only evaluated individually as needed.
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 lazy list is a triple.
returns
a triple of lazy lists, containing the first, second, respectively third member of each element triple of this lazy list.
Definition Classes
LazyList → IterableOps
def updated[B >: A](index: Int, elem: B): LazyList[B]
A copy of this lazy list with one single replaced element.
A copy of this lazy list with one single replaced element.
This method preserves laziness; elements are only evaluated individually as needed.
B
the element type of the returned lazy list.
index
the position of the replacement
elem
the replacing element
returns
a new lazy list which is a copy of this lazy list with the element at position index replaced by elem.
Definition Classes
LazyList → SeqOps
def view: SeqView[A]
A view over the elements of this collection.
A view over the elements of this collection.
Definition Classes
SeqOps → IterableOps
final def wait(): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
Note
not specified by SLS as a member of AnyRef
final def wait(arg0: Long, arg1: Int): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
Note
not specified by SLS as a member of AnyRef
final def wait(arg0: Long): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException]) @native()
Note
not specified by SLS as a member of AnyRef
def withFilter(p: (A) => Boolean): WithFilter[A, LazyList]
A collection.WithFilter which allows GC of the head of lazy list during processing.
A collection.WithFilter which allows GC of the head of lazy list during processing.
This method is not particularly useful for a lazy list, as filter already preserves laziness.
The collection.WithFilter returned by this method preserves laziness; elements are only evaluated individually as needed.
p
the predicate used to test elements.
returns
an object of class WithFilter, which supports map, flatMap, foreach, and withFilter operations. All these operations apply to those elements of this lazy list which satisfy the predicate p.
Definition Classes
LazyList → IterableOps
def writeReplace(): AnyRef
Attributes
protected[this]
def zip[B](that: IterableOnce[B]): LazyList[(A, B)]
Returns a lazy list formed from this lazy list and another iterable collection by combining corresponding elements in pairs.
Returns a lazy list formed from this lazy list and another iterable collection by combining corresponding elements in pairs. If one of the two collections is longer than the other, its remaining elements are ignored.
This method preserves laziness; elements are only evaluated individually as needed.
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 lazy list containing pairs consisting of corresponding elements of this lazy list and that. The length of the returned collection is the minimum of the lengths of this lazy list and that.
Definition Classes
LazyList → IterableOps
def zipAll[A1 >: A, B](that: collection.Iterable[B], thisElem: A1, thatElem: B): LazyList[(A1, B)]
Returns a lazy list formed from this lazy list and another iterable collection by combining corresponding elements in pairs.
Returns a lazy list formed from this lazy list and another iterable collection by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.
This method preserves laziness; elements are only evaluated individually as needed.
that
the iterable providing the second half of each result pair
thisElem
the element to be used to fill up the result if this lazy list is shorter than that.
thatElem
the element to be used to fill up the result if that is shorter than this lazy list.
returns
a new collection of type That containing pairs consisting of corresponding elements of this lazy list and that. The length of the returned collection is the maximum of the lengths of this lazy list and that. If this lazy list is shorter than that, thisElem values are used to pad the result. If that is shorter than this lazy list, thatElem values are used to pad the result.
Definition Classes
LazyList → IterableOps
def zipWithIndex: LazyList[(A, Int)]
Zips this lazy list with its indices.
Zips this lazy list with its indices.
This method preserves laziness; elements are only evaluated individually as needed.
returns
A new lazy list containing pairs consisting of all elements of this lazy list paired with their index. Indices start at 0.
Definition Classes
LazyList → IterableOps → IterableOnceOps

Deprecated Value Members

def /:[B](z: B)(op: (B, A) => B): B
Implicit
This member is added by an implicit conversion from LazyList[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
Shadowing
This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:
(lazyList: IterableOnceExtensionMethods[A])./:(z)(op)
Definition Classes
IterableOnceExtensionMethods
Annotations
@deprecated @inline()
Deprecated
(Since version 2.13.0) Use .iterator.foldLeft instead
final def /:[B](z: B)(op: (B, A) => B): B
Definition Classes
IterableOnceOps
Annotations
@deprecated @inline()
Deprecated
(Since version 2.13.0) Use foldLeft instead of /:
def :\[B](z: B)(op: (A, B) => B): B
Implicit
This member is added by an implicit conversion from LazyList[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
Shadowing
This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:
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Deprecated
(Since version 2.13.0) Use .iterator.foldRight instead
final def :\[B](z: B)(op: (A, B) => B): B
Definition Classes
IterableOnceOps
Annotations
@deprecated @inline()
Deprecated
(Since version 2.13.0) Use foldRight instead of :\
def aggregate[B](z: => B)(seqop: (B, A) => B, combop: (B, B) => B): B
Definition Classes
IterableOnceOps
Annotations
@deprecated
Deprecated
(Since version 2.13.0) aggregate is not relevant for sequential collections. Use foldLeft(z)(seqop) instead.
def collectFirst[B](f: PartialFunction[A, B]): Option[B]
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(Since version 2.13.0) Use .iterator.collectFirst(...) instead
def companion: IterableFactory[[_]LazyList[_]]
Definition Classes
IterableOps
Annotations
@deprecated @deprecatedOverriding(message = "Use iterableFactory instead", since = "2.13.0") @inline()
Deprecated
(Since version 2.13.0) Use iterableFactory instead
def copyToBuffer(dest: Buffer[A]): Unit
Implicit
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@deprecated
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(Since version 2.13.0) Use .iterator.copyToBuffer(...) instead
final def copyToBuffer[B >: A](dest: Buffer[B]): Unit
Definition Classes
IterableOnceOps
Annotations
@deprecated @inline()
Deprecated
(Since version 2.13.0) Use dest ++= coll instead
def count(f: (A) => Boolean): Int
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(Since version 2.13.0) Use .iterator.count(...) instead
def exists(f: (A) => Boolean): Boolean
Implicit
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(Since version 2.13.0) Use .iterator.exists(...) instead
def filter(f: (A) => Boolean): Iterator[A]
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(Since version 2.13.0) Use .iterator.filter(...) instead
def find(p: (A) => Boolean): Option[A]
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(Since version 2.13.0) Use .iterator.find instead
def flatMap[B](f: (A) => IterableOnce[B]): IterableOnce[B]
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(Since version 2.13.0) Use .iterator.flatMap instead or consider requiring an Iterable
def fold[A1 >: A](z: A1)(op: (A1, A1) => A1): A1
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(Since version 2.13.0) Use .iterator.fold instead
def foldLeft[B](z: B)(op: (B, A) => B): B
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(Since version 2.13.0) Use .iterator.foldLeft instead
def foldRight[B](z: B)(op: (A, B) => B): B
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def forall(f: (A) => Boolean): Boolean
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(Since version 2.13.0) Use .iterator.forall(...) instead
def foreach[U](f: (A) => U): Unit
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def hasDefiniteSize: Boolean
Tests whether this lazy list is known to have a finite size.
Tests whether this lazy list is known to have a finite size. All strict collections are known to have finite size. For a non-strict collection such as Stream, the predicate returns true if all elements have been computed. It returns false if the stream is not yet evaluated to the end. Non-empty Iterators usually return false even if they were created from a collection with a known finite size.
Note: many collection methods will not work on collections of infinite sizes. The typical failure mode is an infinite loop. These methods always attempt a traversal without checking first that hasDefiniteSize returns true. However, checking hasDefiniteSize can provide an assurance that size is well-defined and non-termination is not a concern.
This method preserves laziness; elements are only evaluated individually as needed.
returns
true if this collection is known to have finite size, false otherwise.
Definition Classes
LazyList → IterableOnceOps
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Check .knownSize instead of .hasDefiniteSize for more actionable information (see scaladoc for details)
def isEmpty: Boolean
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def map[B](f: (A) => B): IterableOnce[B]
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(Since version 2.13.0) Use .iterator.map instead or consider requiring an Iterable
def max(implicit ord: math.Ordering[A]): A
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def maxBy[B](f: (A) => B)(implicit cmp: math.Ordering[B]): A
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def min(implicit ord: math.Ordering[A]): A
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(Since version 2.13.0) Use .iterator.min instead
def minBy[B](f: (A) => B)(implicit cmp: math.Ordering[B]): A
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def mkString: String
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def mkString(sep: String): String
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def mkString(start: String, sep: String, end: String): String
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def nonEmpty: Boolean
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final def prefixLength(p: (A) => Boolean): Int
Returns the length of the longest prefix whose elements all satisfy some predicate.
Returns the length of the longest prefix whose elements all satisfy some predicate.
Note: may not terminate for infinite-sized collections.
p
the predicate used to test elements.
returns
the length of the longest prefix of this 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 product(implicit num: math.Numeric[A]): A
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def reduce(f: (A, A) => A): A
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def reduceLeft(f: (A, A) => A): A
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def reduceLeftOption(f: (A, A) => A): Option[A]
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def reduceOption(f: (A, A) => A): Option[A]
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def reduceRight(f: (A, A) => A): A
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def reduceRightOption(f: (A, A) => A): Option[A]
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(Since version 2.13.0) Use .iterator.reduceRightOption(...) instead
final def repr: LazyList[A]
Definition Classes
IterableOps
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use coll instead of repr in a collection implementation, use the collection value itself from the outside
def reverseMap[B](f: (A) => B): LazyList[B]
Definition Classes
SeqOps
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use .reverseIterator.map(f).to(...) instead of .reverseMap(f)
def sameElements[B >: A](that: IterableOnce[B]): Boolean
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(Since version 2.13.0) Use .iterator.sameElements instead
def seq: LazyList.this.type
Definition Classes
Iterable
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Iterable.seq always returns the iterable itself
def size: Int
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def sum(implicit num: math.Numeric[A]): A
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(Since version 2.13.0) Use .iterator.sum instead
def to[C1](factory: Factory[A, C1]): C1
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def toArray[B >: A](implicit arg0: ClassTag[B]): Array[B]
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(Since version 2.13.0) Use .iterator.toArray
def toBuffer[B >: A]: Buffer[B]
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(Since version 2.13.0) Use .iterator.to(ArrayBuffer) instead
def toIndexedSeq: collection.IndexedSeq[A]
Implicit
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(Since version 2.13.0) Use .iterator.toIndexedSeq instead
final def toIterable: collection.Iterable[A]
Implicit
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(Since version 2.13.0) Use .iterator.to(Iterable) instead
def toIterator: Iterator[A]
Implicit
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(Since version 2.13.0) Use .iterator instead
final def toIterator: Iterator[A]
Definition Classes
IterableOnceOps
Annotations
@deprecated @inline()
Deprecated
(Since version 2.13.0) Use .iterator instead of .toIterator
def toList: List[A]
Implicit
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(Since version 2.13.0) Use .iterator.to(List) instead
def toMap[K, V](implicit ev: <:<[A, (K, V)]): Map[K, V]
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def toSeq: Seq[A]
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(Since version 2.13.0) Use .iterator.to(Seq) instead
def toSet[B >: A]: Set[B]
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(Since version 2.13.0) Use .iterator.to(Set) instead
def toStream: Stream[A]
Implicit
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Deprecated
(Since version 2.13.0) Use .iterator.to(LazyList) instead
final def toStream: Stream[A]
Definition Classes
IterableOnceOps
Annotations
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Deprecated
(Since version 2.13.0) Use .to(LazyList) instead of .toStream
final def toTraversable: collection.Traversable[A]
Implicit
This member is added by an implicit conversion from LazyList[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
Shadowing
This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:
(lazyList: IterableOnceExtensionMethods[A]).toTraversable
Definition Classes
IterableOnceExtensionMethods
Annotations
@deprecated @inline()
Deprecated
(Since version 2.13.0) Use .iterator.to(Iterable) instead
final def toTraversable: collection.Traversable[A]
Converts this iterable collection to an unspecified Iterable.
Converts this iterable collection to an unspecified Iterable. Will return the same collection if this instance is already Iterable.
returns
An Iterable containing all elements of this iterable collection.
Definition Classes
IterableOps
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use toIterable instead
def toVector: Vector[A]
Implicit
This member is added by an implicit conversion from LazyList[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
Shadowing
This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:
(lazyList: IterableOnceExtensionMethods[A]).toVector
Definition Classes
IterableOnceExtensionMethods
Annotations
@deprecated @inline()
Deprecated
(Since version 2.13.0) Use .iterator.to(Vector) instead
final def union[B >: A](that: collection.Seq[B]): LazyList[B]
Produces a new sequence which contains all elements of this sequence and also all elements of a given sequence.
Produces a new sequence which contains all elements of this sequence and also all elements of a given sequence. xs union ys is equivalent to xs ++ ys.
B
the element type of the returned sequence.
that
the sequence to add.
returns
a new collection which contains all elements of this 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[A]
A view over a slice of the elements of this collection.
A view over a slice of the elements of this collection.
Definition Classes
IterableOps
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use .view.slice(from, until) instead of .view(from, until)
def withFilter(f: (A) => Boolean): Iterator[A]
Implicit
This member is added by an implicit conversion from LazyList[A] toIterableOnceExtensionMethods[A] performed by method iterableOnceExtensionMethods in scala.collection.IterableOnce.
Shadowing
This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:
(lazyList: IterableOnceExtensionMethods[A]).withFilter(f)
Definition Classes
IterableOnceExtensionMethods
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use .iterator.withFilter(...) instead
def →[B](y: B): (LazyList[A], B)
Implicit
This member is added by an implicit conversion from LazyList[A] toArrowAssoc[LazyList[A]] performed by method ArrowAssoc in scala.Predef.This conversion will take place only if A is a subclass of Option[Nothing] (A <: Option[Nothing]).
Definition Classes
ArrowAssoc
Annotations
@deprecated
Deprecated
(Since version 2.13.0) Use -> instead. If you still wish to display it as one character, consider using a font with programming ligatures such as Fira Code.

Packages

Package structure

Automatic imports

LazyList

Companion object LazyList

final class LazyList[+A] extends AbstractSeq[A] with LinearSeq[A] with LinearSeqOps[A, LazyList, LazyList[A]] with IterableFactoryDefaults[A, LazyList] with Serializable

Value Members

Deprecated Value Members

Inherited from java.io.Serializable

Inherited from LinearSeq[A]

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

Inherited from collection.LinearSeq[A]

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

Inherited from AbstractSeq[A]

Inherited from Seq[A]

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

Inherited from Iterable[A]

Inherited from collection.AbstractSeq[A]

Inherited from collection.Seq[A]

Inherited from Equals

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

Inherited from PartialFunction[Int, A]

Inherited from (Int) => A

Inherited from AbstractIterable[A]

Inherited from collection.Iterable[A]

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

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

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

Inherited from IterableOnce[A]

Inherited from AnyRef

Inherited from Any

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

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

Inherited by implicit conversion toDeferrer fromLazyList[A] to Deferrer[A]

Inherited by implicit conversion any2stringadd fromLazyList[A] to any2stringadd[LazyList[A]]

Inherited by implicit conversion StringFormat fromLazyList[A] to StringFormat[LazyList[A]]

Inherited by implicit conversion Ensuring fromLazyList[A] to Ensuring[LazyList[A]]

Inherited by implicit conversion ArrowAssoc fromLazyList[A] to ArrowAssoc[LazyList[A]]

Ungrouped

Packages

Package structure

Automatic imports

LazyList

Companion object LazyList

final class LazyList[+A] extends AbstractSeq[A] with LinearSeq[A] with LinearSeqOps[A, LazyList, LazyList[A]] with IterableFactoryDefaults[A, LazyList] with Serializable

Value Members

Deprecated Value Members

Inherited from java.io.Serializable

Inherited from LinearSeq[A]

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

Inherited from collection.LinearSeq[A]

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

Inherited from AbstractSeq[A]

Inherited from Seq[A]

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

Inherited from Iterable[A]

Inherited from collection.AbstractSeq[A]

Inherited from collection.Seq[A]

Inherited from Equals

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

Inherited from PartialFunction[Int, A]

Inherited from (Int) => A

Inherited from AbstractIterable[A]

Inherited from collection.Iterable[A]

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

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

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

Inherited from IterableOnce[A]

Inherited from AnyRef

Inherited from Any

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

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

Inherited by implicit conversion toDeferrer fromLazyList[A] to Deferrer[A]

Inherited by implicit conversion any2stringadd fromLazyList[A] to any2stringadd[LazyList[A]]

Inherited by implicit conversion StringFormat fromLazyList[A] to StringFormat[LazyList[A]]

Inherited by implicit conversion Ensuring fromLazyList[A] to Ensuring[LazyList[A]]

Inherited by implicit conversion ArrowAssoc fromLazyList[A] to ArrowAssoc[LazyList[A]]

Ungrouped

LazyList