Collect

@SerialVersionUID(3L)
class Collect[+A, B](underlying: SomeIterableOps[A], pf: PartialFunction[A, B]) extends AbstractView[B]

A view that collects elements of the underlying collection.

Source:
View.scala
class AbstractView[B]
trait View[B]
trait Iterable[B]
trait IterableOps[B, View, View[B]]
trait IterableOnceOps[B, View, View[B]]
trait IterableOnce[B]
class Object
trait Matchable
class Any

Value members

Concrete methods

Inherited methods

final def ++[B >: B](suffix: IterableOnce[B]): View[B]

Alias for concat

Alias for concat

Inherited from:
IterableOps
Source:
Iterable.scala

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
Value parameters:
b

the string builder to which elements are appended.

Returns:

the string builder b to which elements were appended.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala

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
Value parameters:
b

the string builder to which elements are appended.

sep

the separator string.

Returns:

the string builder b to which elements were appended.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala

Appends all elements of this collection to a string builder using start, end, and separator strings.

Appends all elements of this collection 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 collection are 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 , "List(" , ", " , ")")
res5: StringBuilder = List(1, 2, 3, 4)
Value parameters:
b

the string builder to which elements are appended.

end

the ending string.

sep

the separator string.

start

the starting string.

Returns:

the string builder b to which elements were appended.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def collect[B](pf: PartialFunction[B, B]): View[B]
Inherited from:
IterableOps
Source:
Iterable.scala
def collectFirst[B](pf: PartialFunction[B, B]): Option[B]

Finds the first element of the collection for which the given partial function is defined, and applies the partial function to it.

Finds the first element of the collection for which the given partial function is defined, and applies the partial function to it.

Note: may not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters:
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.

Example:

Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def concat[B >: B](suffix: IterableOnce[B]): View[B]

Returns a new iterable collection containing the elements from the left hand operand followed by the elements from the right hand operand.

Returns a new iterable collection containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the iterable collection is the most specific superclass encompassing the element types of the two operands.

Type parameters:
B

the element type of the returned collection.

Value parameters:
suffix

the traversable to append.

Returns:

a new iterable collection which contains all elements of this iterable collection followed by all elements of suffix.

Inherited from:
IterableOps
Source:
Iterable.scala
def copyToArray[B >: B](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.

Type parameters:
B

the type of the elements of the array.

Value parameters:
len

the maximal number of elements to copy.

start

the starting index of xs.

xs

the array to fill.

Returns:

the number of elements written to the array

Note:

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
@deprecatedOverriding("This should always forward to the 3-arg version of this method", since = "2.13.4")
def copyToArray[B >: B](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.

Type parameters:
B

the type of the elements of the array.

Value parameters:
start

the starting index of xs.

xs

the array to fill.

Returns:

the number of elements written to the array

Note:

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
@deprecatedOverriding("This should always forward to the 3-arg version of this method", since = "2.13.4")
def copyToArray[B >: B](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.

Type parameters:
B

the type of the elements of the array.

Value parameters:
xs

the array to fill.

Returns:

the number of elements written to the array

Note:

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def corresponds[B](that: IterableOnce[B])(p: (B, 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.

Type parameters:
B

the type of the elements of that

Value parameters:
p

the test predicate, which relates elements from both collections

that

the other collection

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

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def count(p: B => 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.

Value parameters:
p

the predicate used to test elements.

Returns:

the number of elements satisfying the predicate p.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def drop(n: Int): View[B]
Inherited from:
IterableOps
Source:
Iterable.scala
def dropRight(n: Int): View[B]

Selects all elements except last n ones.

Selects all elements except last n ones.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters:
n

the number of elements to drop from this iterable collection.

Returns:

a iterable collection consisting of all elements of this iterable collection except the last n ones, or else the empty iterable collection, if this iterable collection has less than n elements. If n is negative, don't drop any elements.

Inherited from:
IterableOps
Source:
Iterable.scala
def dropWhile(p: B => Boolean): View[B]
Inherited from:
IterableOps
Source:
Iterable.scala
override def empty: View[B]
Definition Classes
Inherited from:
View
Source:
View.scala
def exists(p: B => Boolean): Boolean

Tests whether a predicate holds for at least one element of this collection.

Tests whether a predicate holds for at least one element of this collection.

Note: may not terminate for infinite-sized collections.

Value parameters:
p

the predicate used to test elements.

Returns:

true if the given predicate p is satisfied by at least one element of this collection, otherwise false

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def filter(pred: B => Boolean): View[B]
Inherited from:
IterableOps
Source:
Iterable.scala
def filterNot(pred: B => Boolean): View[B]
Inherited from:
IterableOps
Source:
Iterable.scala
def find(p: B => Boolean): Option[B]

Finds the first element of the collection satisfying a predicate, if any.

Finds the first element of the collection satisfying a predicate, if any.

Note: may not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters:
p

the predicate used to test elements.

Returns:

an option value containing the first element in the collection that satisfies p, or None if none exists.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def flatMap[B](f: B => IterableOnce[B]): View[B]
Inherited from:
IterableOps
Source:
Iterable.scala
def flatten[B](implicit asIterable: B => IterableOnce[B]): View[B]
Inherited from:
IterableOps
Source:
Iterable.scala
def fold[A1 >: B](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.

Type parameters:
A1

a type parameter for the binary operator, a supertype of A.

Value parameters:
op

a binary operator that must be associative.

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).

Returns:

the result of applying the fold operator op between all the elements and z, or z if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def foldLeft[B](z: B)(op: (B, B) => B): B

Applies a binary operator to a start value and all elements of this collection, going left to right.

Applies a binary operator to a start value and 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.

Type parameters:
B

the result type of the binary operator.

Value parameters:
op

the binary operator.

z

the start value.

Returns:

the result of inserting op between consecutive elements of this collection, going left to right with the start value z on the left: op(...op(z, x1), x2, ..., xn) where x1, ..., xn are the elements of this collection. Returns z if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def foldRight[B](z: B)(op: (B, 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.

Type parameters:
B

the result type of the binary operator.

Value parameters:
op

the binary operator.

z

the start value.

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(x1, op(x2, ... op(xn, z)...)) where x1, ..., xn are the elements of this collection. Returns z if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def forall(p: B => Boolean): Boolean

Tests whether a predicate holds for all elements of this collection.

Tests whether a predicate holds for all elements of this collection.

Note: may not terminate for infinite-sized collections.

Value parameters:
p

the predicate used to test elements.

Returns:

true if this collection is empty or the given predicate p holds for all elements of this collection, otherwise false.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def foreach[U](f: B => U): Unit

Apply f to each element for its side effects Note: [U] parameter needed to help scalac's type inference.

Apply f to each element for its side effects Note: [U] parameter needed to help scalac's type inference.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
protected def fromSpecific(coll: IterableOnce[B]): View[B]
def groupBy[K](f: B => K): Map[K, View[B]]

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.

Type parameters:
K

the type of keys returned by the discriminator function.

Value parameters:
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.

Inherited from:
IterableOps
Source:
Iterable.scala
def groupMap[K, B](key: B => K)(f: B => B): Map[K, View[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.

Type parameters:
B

the type of values returned by the transformation function

K

the type of keys returned by the discriminator function

Value parameters:
f

the element transformation function

key

the discriminator function

Inherited from:
IterableOps
Source:
Iterable.scala
def groupMapReduce[K, B](key: B => K)(f: B => 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 f 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.

Inherited from:
IterableOps
Source:
Iterable.scala
def grouped(size: Int): Iterator[View[B]]

Partitions elements in fixed size iterable collections.

Partitions elements in fixed size iterable collections.

Value parameters:
size

the number of elements per group

Returns:

An iterator producing iterable collections of size size, except the last will be less than size size if the elements don't divide evenly.

See also:
Inherited from:
IterableOps
Source:
Iterable.scala
def head: B

Selects the first element of this iterable collection.

Selects the first element of this iterable collection.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Returns:

the first element of this iterable collection.

Throws:
NoSuchElementException

if the iterable collection is empty.

Inherited from:
IterableOps
Source:
Iterable.scala

Optionally selects the first element.

Optionally selects the first element.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Returns:

the first element of this iterable collection if it is nonempty, None if it is empty.

Inherited from:
IterableOps
Source:
Iterable.scala
def init: View[B]

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.

Inherited from:
IterableOps
Source:
Iterable.scala

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

Example:

List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)

Inherited from:
IterableOps
Source:
Iterable.scala

Tests whether the collection is empty.

Tests whether the collection is empty.

Note: Implementations in subclasses that are not repeatedly traversable must take care not to consume any elements when isEmpty is called.

Returns:

true if the collection contains no elements, false otherwise.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
Definition Classes
Inherited from:
IterableOps
Source:
Iterable.scala
Definition Classes
Inherited from:
View
Source:
View.scala
Returns:

The number of elements in this collection, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.

Inherited from:
IterableOnce
Source:
IterableOnce.scala
def last: B

Selects the last element.

Selects the last element.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Returns:

The last element of this iterable collection.

Throws:
NoSuchElementException

If the iterable collection is empty.

Inherited from:
IterableOps
Source:
Iterable.scala

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.

Inherited from:
IterableOps
Source:
Iterable.scala
def lazyZip[B](that: Iterable[B]): LazyZip2[B, B, Collect[A, B]]

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)
Type parameters:
B

the type of the second element in each eventual pair

Value parameters:
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.

Inherited from:
Iterable
Source:
Iterable.scala
def map[B](f: B => B): View[B]
Inherited from:
IterableOps
Source:
Iterable.scala
def max[B >: B](implicit ord: Ordering[B]): B

Finds the largest element.

Finds the largest element.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The type over which the ordering is defined.

Value parameters:
ord

An ordering to be used for comparing elements.

Returns:

the largest element of this collection with respect to the ordering ord.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def maxBy[B](f: B => B)(implicit cmp: Ordering[B]): B

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.

Type parameters:
B

The result type of the function f.

Value parameters:
cmp

An ordering to be used for comparing elements.

f

The measuring function.

Returns:

the first element of this collection with the largest value measured by function f with respect to the ordering cmp.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def maxByOption[B](f: B => B)(implicit cmp: Ordering[B]): Option[B]

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.

Type parameters:
B

The result type of the function f.

Value parameters:
cmp

An ordering to be used for comparing elements.

f

The measuring function.

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.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def maxOption[B >: B](implicit ord: Ordering[B]): Option[B]

Finds the largest element.

Finds the largest element.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The type over which the ordering is defined.

Value parameters:
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.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def min[B >: B](implicit ord: Ordering[B]): B

Finds the smallest element.

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The type over which the ordering is defined.

Value parameters:
ord

An ordering to be used for comparing elements.

Returns:

the smallest element of this collection with respect to the ordering ord.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def minBy[B](f: B => B)(implicit cmp: Ordering[B]): B

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.

Type parameters:
B

The result type of the function f.

Value parameters:
cmp

An ordering to be used for comparing elements.

f

The measuring function.

Returns:

the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def minByOption[B](f: B => B)(implicit cmp: Ordering[B]): Option[B]

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.

Type parameters:
B

The result type of the function f.

Value parameters:
cmp

An ordering to be used for comparing elements.

f

The measuring function.

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.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def minOption[B >: B](implicit ord: Ordering[B]): Option[B]

Finds the smallest element.

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The type over which the ordering is defined.

Value parameters:
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.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
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.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
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.

Value parameters:
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.

Example:

List(1, 2, 3).mkString("|") = "1|2|3"

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
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.

Value parameters:
end

the ending string.

sep

the separator string.

start

the starting 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.

Example:

List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
protected def newSpecificBuilder: Builder[B, View[B]]
@deprecatedOverriding("nonEmpty is defined as !isEmpty; override isEmpty instead", "2.13.0")

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.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def partition(p: B => Boolean): (View[B], View[B])

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.

Inherited from:
IterableOps
Source:
Iterable.scala
def partitionMap[A1, A2](f: B => Either[A1, A2]): (View[A1], View[A2])

Applies a function f to each element of the iterable collection and returns a pair of iterable collections: the first one made of those values returned 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 iterable collection and returns a pair of iterable collections: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.

Example:

val xs = Iterable(1, "one", 2, "two", 3, "three") partitionMap {
 case i: Int => Left(i)
 case s: String => Right(s)
}
// xs == (Iterable(1, 2, 3),
//        Iterable(one, two, three))
Type parameters:
A1

the element type of the first resulting collection

A2

the element type of the second resulting collection

Value parameters:
f

the 'split function' mapping the elements of this iterable collection to an scala.util.Either

Returns:

a pair of iterable collections: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.

Inherited from:
IterableOps
Source:
Iterable.scala
def product[B >: B](implicit num: 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.

Type parameters:
B

the result type of the * operator.

Value parameters:
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.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def reduce[B >: B](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.

Type parameters:
B

A type parameter for the binary operator, a supertype of A.

Value parameters:
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.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def reduceLeft[B >: B](op: (B, B) => B): B

Applies a binary operator to all elements of this collection, going left to right.

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.

Type parameters:
B

the result type of the binary operator.

Value parameters:
op

the binary operator.

Returns:

the result of inserting op between consecutive elements of this collection, going left to right: op( op( ... op(x1, x2) ..., xn-1), xn) where x1, ..., xn are the elements of this collection.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def reduceLeftOption[B >: B](op: (B, B) => 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.

Type parameters:
B

the result type of the binary operator.

Value parameters:
op

the binary operator.

Returns:

an option value containing the result of reduceLeft(op) if this collection is nonempty, None otherwise.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def reduceOption[B >: B](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.

Type parameters:
B

A type parameter for the binary operator, a supertype of A.

Value parameters:
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.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def reduceRight[B >: B](op: (B, 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.

Type parameters:
B

the result type of the binary operator.

Value parameters:
op

the binary operator.

Returns:

the result of inserting op between consecutive elements of this collection, going right to left: op(x1, op(x2, ..., op(xn-1, xn)...)) where x1, ..., xn are the elements of this collection.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def reduceRightOption[B >: B](op: (B, 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.

Type parameters:
B

the result type of the binary operator.

Value parameters:
op

the binary operator.

Returns:

an option value containing the result of reduceRight(op) if this collection is nonempty, None otherwise.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
protected def reversed: Iterable[B]
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def scan[B >: B](z: B)(op: (B, B) => B): View[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.

Type parameters:
B

element type of the resulting collection

Value parameters:
op

the associative operator for the scan

z

neutral element for the operator op

Returns:

a new iterable collection containing the prefix scan of the elements in this iterable collection

Inherited from:
IterableOps
Source:
Iterable.scala
def scanLeft[B](z: B)(op: (B, B) => B): View[B]
Inherited from:
IterableOps
Source:
Iterable.scala
def scanRight[B](z: B)(op: (B, B) => B): View[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)
Type parameters:
B

the type of the elements in the resulting collection

Value parameters:
op

the binary operator applied to the intermediate result and the element

z

the initial value

Returns:

collection with intermediate results

Inherited from:
IterableOps
Source:
Iterable.scala
def size: Int

The size of this collection.

The size of this collection.

Note: will not terminate for infinite-sized collections.

Returns:

the number of elements in this collection.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def sizeCompare(that: Iterable[_]): Int

Compares the size of this iterable collection to the size of another Iterable.

Compares the size of this iterable collection to the size of another Iterable.

Value parameters:
that

the Iterable whose size is compared with this iterable collection'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.

Inherited from:
IterableOps
Source:
Iterable.scala
def sizeCompare(otherSize: Int): Int

Compares the size of this iterable collection to a test value.

Compares the size of this iterable collection to a test value.

Value parameters:
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.

See also:
Inherited from:
IterableOps
Source:
Iterable.scala

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
Inherited from:
IterableOps
Source:
Iterable.scala
def slice(from: Int, until: Int): View[B]
Inherited from:
IterableOps
Source:
Iterable.scala
def sliding(size: Int, step: Int): Iterator[View[B]]

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.

Value parameters:
size

the number of elements per group

step

the distance between the first elements of successive groups

Returns:

An iterator producing iterable collections of size size, except the last element (which may be the only element) will be smaller if there are fewer than size elements remaining to be grouped.

See also:
Example:

List(1, 2, 3, 4, 5).sliding(2, 2) = Iterator(List(1, 2), List(3, 4), List(5))

List(1, 2, 3, 4, 5, 6).sliding(2, 3) = Iterator(List(1, 2), List(4, 5))

Inherited from:
IterableOps
Source:
Iterable.scala
def sliding(size: Int): Iterator[View[B]]

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.

Value parameters:
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.

See also:
Example:

List().sliding(2) = empty iterator

List(1).sliding(2) = Iterator(List(1))

List(1, 2).sliding(2) = Iterator(List(1, 2))

List(1, 2, 3).sliding(2) = Iterator(List(1, 2), List(2, 3))

Inherited from:
IterableOps
Source:
Iterable.scala
def span(p: B => Boolean): (View[B], View[B])
Inherited from:
IterableOps
Source:
Iterable.scala
override def splitAt(n: Int): (View[B], View[B])
Definition Classes
Inherited from:
IterableOps
Source:
Iterable.scala
def stepper[S <: Stepper[_]](implicit shape: StepperShape[B, 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.

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.

Inherited from:
IterableOnce
Source:
IterableOnce.scala
def sum[B >: B](implicit num: 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.

Type parameters:
B

the result type of the + operator.

Value parameters:
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.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def tail: View[B]

The rest of the collection without its first element.

The rest of the collection without its first element.

Inherited from:
IterableOps
Source:
Iterable.scala

Iterates over the tails of this iterable collection.

Iterates over the tails of this iterable collection. The first value will be this iterable collection and the final one will be an empty iterable collection, with the intervening values the results of successive applications of tail.

Returns:

an iterator over all the tails of this iterable collection

Example:

List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)

Inherited from:
IterableOps
Source:
Iterable.scala
def take(n: Int): View[B]
Inherited from:
IterableOps
Source:
Iterable.scala
def takeRight(n: Int): View[B]

Selects the last n elements.

Selects the last n elements.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters:
n

the number of elements to take from this iterable collection.

Returns:

a iterable collection consisting only of the last n elements of this iterable collection, or else the whole iterable collection, if it has less than n elements. If n is negative, returns an empty iterable collection.

Inherited from:
IterableOps
Source:
Iterable.scala
def takeWhile(p: B => Boolean): View[B]

Takes longest prefix of elements that satisfy a predicate.

Takes longest prefix of elements that satisfy a predicate.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters:
p

The predicate used to test elements.

Returns:

the longest prefix of this iterable collection whose elements all satisfy the predicate p.

Inherited from:
IterableOps
Source:
Iterable.scala
override def tapEach[U](f: B => U): View[B]
Definition Classes
Inherited from:
IterableOps
Source:
Iterable.scala
def to[C1](factory: Factory[B, 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]

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def toArray[B >: B : ClassTag]: Array[B]

Convert collection to array.

Convert collection to array.

Implementation note: DO NOT call Array.from from this method.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
final def toBuffer[B >: B]: Buffer[B]
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def toList: List[B]
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def toMap[K, V](implicit ev: B <:< (K, V)): Map[K, V]
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def toSeq: Seq[B]
Returns:

This collection as a Seq[A]. This is equivalent to to(Seq) but might be faster.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def toSet[B >: B]: Set[B]
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
override def toString: String
Definition Classes
Inherited from:
View
Source:
View.scala
def transpose[B](implicit asIterable: B => Iterable[B]): View[View[B]]

Transposes this iterable collection of iterable collections into a iterable collection of iterable collections.

Transposes this iterable collection of iterable collections into a iterable collection of iterable collections.

The resulting collection's type will be guided by the static type of iterable collection. For example:

val xs = List(
           Set(1, 2, 3),
           Set(4, 5, 6)).transpose
// xs == List(
//         List(1, 4),
//         List(2, 5),
//         List(3, 6))

val ys = Vector(
           List(1, 2, 3),
           List(4, 5, 6)).transpose
// ys == Vector(
//         Vector(1, 4),
//         Vector(2, 5),
//         Vector(3, 6))

Note: Even when applied to a view or a lazy collection it will always force the elements.

Type parameters:
B

the type of the elements of each iterable collection.

Value parameters:
asIterable

an implicit conversion which asserts that the element type of this iterable collection is an Iterable.

Returns:

a two-dimensional iterable collection of iterable collections which has as nth row the nth column of this iterable collection.

Throws:
IllegalArgumentException

if all collections in this iterable collection are not of the same size.

Inherited from:
IterableOps
Source:
Iterable.scala
def unzip[A1, A2](implicit asPair: B => (A1, A2)): (View[A1], View[A2])

Converts this iterable collection of pairs into two collections of the first and second half of each pair.

Converts this iterable collection of pairs into two collections of the first and second half of each pair.

val xs = Iterable(
           (1, "one"),
           (2, "two"),
           (3, "three")).unzip
// xs == (Iterable(1, 2, 3),
//        Iterable(one, two, three))
Type parameters:
A1

the type of the first half of the element pairs

A2

the type of the second half of the element pairs

Value parameters:
asPair

an implicit conversion which asserts that the element type of this iterable collection is a pair.

Returns:

a pair of iterable collections, containing the first, respectively second half of each element pair of this iterable collection.

Inherited from:
IterableOps
Source:
Iterable.scala
def unzip3[A1, A2, A3](implicit asTriple: B => (A1, A2, A3)): (View[A1], View[A2], View[A3])

Converts this iterable collection of triples into three collections of the first, second, and third element of each triple.

Converts this iterable collection of triples into three collections of the first, second, and third element of each triple.

val xs = Iterable(
           (1, "one", '1'),
           (2, "two", '2'),
           (3, "three", '3')).unzip3
// xs == (Iterable(1, 2, 3),
//        Iterable(one, two, three),
//        Iterable(1, 2, 3))
Type parameters:
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

Value parameters:
asTriple

an implicit conversion which asserts that the element type of this iterable collection is a triple.

Returns:

a triple of iterable collections, containing the first, second, respectively third member of each element triple of this iterable collection.

Inherited from:
IterableOps
Source:
Iterable.scala
override def view: View[B]
Definition Classes
Inherited from:
View
Source:
View.scala
def withFilter(p: B => Boolean): WithFilter[B, View]

Creates a non-strict filter of this iterable collection.

Creates a non-strict filter of this iterable collection.

Note: the difference between c filter p and c withFilter p is that the former creates a new collection, whereas the latter only restricts the domain of subsequent map, flatMap, foreach, and withFilter operations.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters:
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 iterable collection which satisfy the predicate p.

Inherited from:
IterableOps
Source:
Iterable.scala
def zip[B](that: IterableOnce[B]): View[(B, B)]

Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs.

Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs. If one of the two collections is longer than the other, its remaining elements are ignored.

Type parameters:
B

the type of the second half of the returned pairs

Value parameters:
that

The iterable providing the second half of each result pair

Returns:

a new iterable collection containing pairs consisting of corresponding elements of this iterable collection and that. The length of the returned collection is the minimum of the lengths of this iterable collection and that.

Inherited from:
IterableOps
Source:
Iterable.scala
def zipAll[A1 >: B, B](that: Iterable[B], thisElem: A1, thatElem: B): View[(A1, B)]

Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs.

Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.

Value parameters:
that

the iterable providing the second half of each result pair

thatElem

the element to be used to fill up the result if that is shorter than this iterable collection.

thisElem

the element to be used to fill up the result if this iterable collection is shorter than that.

Returns:

a new collection of type That containing pairs consisting of corresponding elements of this iterable collection and that. The length of the returned collection is the maximum of the lengths of this iterable collection and that. If this iterable collection is shorter than that, thisElem values are used to pad the result. If that is shorter than this iterable collection, thatElem values are used to pad the result.

Inherited from:
IterableOps
Source:
Iterable.scala
def zipWithIndex: View[(B, Int)]
Inherited from:
IterableOps
Source:
Iterable.scala

Deprecated and Inherited methods

@deprecated("Use ++ instead of ++: for collections of type Iterable", "2.13.0")
def ++:[B >: B](that: IterableOnce[B]): View[B]
Deprecated
Inherited from:
IterableOps
Source:
Iterable.scala
@deprecated("Use foldLeft instead of /:", "2.13.0") @inline
final def /:[B](z: B)(op: (B, B) => B): B
Deprecated
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
@deprecated("Use foldRight instead of :\\", "2.13.0") @inline
final def :\[B](z: B)(op: (B, B) => B): B
Deprecated
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
@deprecated("`aggregate` is not relevant for sequential collections. Use `foldLeft(z)(seqop)` instead.", "2.13.0")
def aggregate[B](z: => B)(seqop: (B, B) => B, combop: (B, B) => B): B
Deprecated
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
@deprecated("Use iterableFactory instead", "2.13.0") @deprecatedOverriding("Use iterableFactory instead", "2.13.0") @inline
Deprecated
Inherited from:
IterableOps
Source:
Iterable.scala
@deprecated("Use `dest ++= coll` instead", "2.13.0") @inline
final def copyToBuffer[B >: B](dest: Buffer[B]): Unit
Deprecated
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
@deprecated("Views no longer know about their underlying collection type; .force always returns an IndexedSeq", "2.13.0") @inline
Deprecated
Inherited from:
View
Source:
View.scala
@deprecated("Check .knownSize instead of .hasDefiniteSize for more actionable information (see scaladoc for details)", "2.13.0")

Tests whether this collection is known to have a finite size.

Tests whether this collection is known to have a finite size. All strict collections are known to have finite size. For a non-strict collection such as Stream, the predicate 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.

Returns:

true if this collection is known to have finite size, false otherwise.

See also:

method knownSize for a more useful alternative

Deprecated

This method is deprecated in 2.13 because it does not provide any actionable information. As noted above, even the collection library itself does not use it. When there is no guarantee that a collection is finite, it is generally best to attempt a computation anyway and document that it will not terminate for infinite collections rather than backing out because this would prevent performing the computation on collections that are in fact finite even though hasDefiniteSize returns false.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
@deprecated("Use coll instead of repr in a collection implementation, use the collection value itself from the outside", "2.13.0")
final def repr: View[B]
Deprecated
Inherited from:
IterableOps
Source:
Iterable.scala
@deprecated("Iterable.seq always returns the iterable itself", "2.13.0")
def seq: Collect[A, B]
Deprecated
Inherited from:
Iterable
Source:
Iterable.scala
@deprecated("toIterable is internal and will be made protected; its name is similar to `toList` or `toSeq`, but it doesn\'t copy non-immutable collections", "2.13.7")
final def toIterable: Collect[A, B]
Deprecated
Inherited from:
Iterable
Source:
Iterable.scala
@deprecated("Use .iterator instead of .toIterator", "2.13.0") @inline
final def toIterator: Iterator[B]
Deprecated
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
@deprecated("Use .to(LazyList) instead of .toStream", "2.13.0") @inline
final def toStream: Stream[B]
Deprecated
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
@deprecated("toTraversable is internal and will be made protected; its name is similar to `toList` or `toSeq`, but it doesn\'t copy non-immutable collections", "2.13.0")
final def toTraversable: Iterable[B]

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.

Deprecated
Inherited from:
IterableOps
Source:
Iterable.scala
@deprecated("Use .view.slice(from, until) instead of .view(from, until)", "2.13.0")
def view(from: Int, until: Int): View[B]

A view over a slice of the elements of this collection.

A view over a slice of the elements of this collection.

Deprecated
Inherited from:
IterableOps
Source:
Iterable.scala