Returns [].

Returns [].

Returns true.

Returns [].

Returns null.

Returns [].

Returns [].

Returns null.

Returns null.

Returns [].

Returns [].

Returns [].

Returns 0.

Returns a string description of the empty sequence: [].

Determines if there is at least one element of this stream that satisfies the given predicate function. If the stream is empty, returns false. For an infinite stream, this operation might not terminate.

Return a sequence containing the elements of this sequence, in the order in which they occur in this sequence, followed by the given elements, in the order in which they occur in the given sequence.

Produces a stream containing every stepth element of this stream. If the step size is 1, the resulting stream contains the same elements as this stream.

For example, the expression

(0..10).by(3)

results in the stream { 0, 3, 6, 9 }.

The step size must be greater than zero.

Returns the given other iterable object.

Returns [].

Produce a new sequence containing the results of applying the given mapping to the elements of this stream.

This operation is an eager counterpart to Iterable.map(). For any stream it, and mapping f:

it.collect(f) == [*it.map(f)]

Returns false for any given element.

Returns 0 for any given predicate.

Produces a stream containing the elements of this stream, in the order in which they occur in this stream, after replacing every null element in the stream with the given default value. The value null does not ocur in the resulting stream.

For example, the expression

{ "123", "abc", "456" }.map(parseInteger).defaultNullElements(0)

results in the stream { 123, 0, 456 }.

Returns false for any given index.

Call the given function for each element of this stream, passing the elements in the order they occur in this stream.

For example:

words.each((word) {
    print(word.lowercased);
    print(word.uppercased);
});

Has the same effect as the following for loop:

for (word in words) {
    print(word.lowercased);
    print(word.uppercased);
}

For certain streams this method is highly efficient, surpassing the performance of for loops on the JVM. Thus, each() is sometimes preferred in highly performance-critical low-level code.

Determines if all elements of this stream satisfy the given predicate function. If the stream is empty, return true. For an infinite stream, this operation might not terminate.

Produces a stream containing the elements of this stream that satisfy the given predicate function.

For any empty stream, filter() returns an empty stream:

{}.filter(p) == {}

For any nonempty stream it, and predicate p, the result of filter() may be obtained according to this recursive definition:

it.filter(p) == { if (p(it.first)) it.first }.chain(it.rest.filter(f))

Alternatively, and in practice, filter() may be defined by this comprehension:

it.filter(p) == { for (e in it) if (p(e)) e };

For example, the expression

(1..100).filter(13.divides)

results in the stream { 13, 26, 39, 52, 65, 78, 91 }.

The first element of this stream which is not null and satisfies the given predicate function, if any, or null if there is no such element. For an infinite stream, this method might not terminate.

For example, the expression

(-10..10).find(Integer.positive)

evaluates to 1.

The first index in this list for which the element is not null and satisfies the given predicate function.

Given a mapping function that accepts an Element and returns a stream of Results, produces a new stream containing all elements of every Result stream that results from applying the function to the elements of this stream.

For example, the expression

{ "Hello", "World" }.flatMap(String.lowercased)

results in this stream:

{ 'h', 'e', 'l', 'l', 'o', 'w', 'o', 'r,' 'l', 'd' }

The expression

{ "hello"->"hola", "world"->"mundo" }
        .flatMap(Entry<String,String>.pair)

produces this stream:

{ "hello", "hola", "world", "mundo" }

Beginning with a given initial value, apply the given combining function to each element of this stream in turn, progressively accumulating a single result.

For an empty stream, fold() returns the given initial value z:

{}.fold(z)(f) == z

For a given nonempty stream it, initial value z, and combining function f, the result of fold() is obtained according to the following recursive definition:

it.fold(z)(f) == f(it.exceptLast.fold(z)(f), it.last)

For example, the expression

(1..100).fold(0)(plus)

results in the integer 5050.

Produces a stream with a given initial element, followed by the elements of this stream, in the order in which they occur in this stream.

For example, the expression

(1..3).follow(0)

evaluates to the stream { 0, 1, 2, 3 }.

Note that the expression stream.follow(head) eagerly evaluates head, and therefore is not precisely the same as this enumeration expression, where head is evaluated lazily:

{ head, *stream }

Returns null for any given index.

Returns null for any given index.

Returns [].

The indexes in this list for which the element is not null and satisfies the given predicate function.

Select the first elements of this list, returning a list no longer than the given length. If this list is shorter than the given length, return this list. Otherwise return a list of the given length. If length<=0 return an empty list.

For any list, and for any integer length:

list.initial(length) == list[...length-1] == list[0:length]

This is an eager operation.

Returns an iterator that is already exhausted.

The last index in this list for which the element is not null and satisfies the given predicate function.

Produces a stream containing the results of applying the given mapping to the elements of this stream.

For any empty stream, map() returns an empty stream:

{}.map(f) == {}

For any nonempty stream it, and mapping function f, the result of map() may be obtained according to this recursive definition:

it.map(f).first == f(it.first)
it.map(f).rest == it.rest.map(f)

Alternatively, and in practice, map() may be defined by this comprehension:

it.map(f) == { for (e in it) f(e) }

For example, the expression

(0..4).map(10.power)

results in the stream { 1, 10, 100, 1000, 10000 }.

Returns [] for any given measure.

Return a sequence containing the given elements, in the order in which they occur in the given sequence, followed by the elements of this sequence, in the order in which they occur in this sequence.

Beginning with the Iterable.first element of this stream, apply the given combining function to each element of this stream in turn, progressively accumulating a single result.

For an empty stream, reduce() always returns null.

For a stream with one element, reduce() returns that element:

{ first }.reduce(f) == first

For a given stream it with more than one element, and combining function f, the result of reduce() is obtained according to the following recursive definition:

it.reduce(f) == f(it.exceptLast.reduce(f), it.last)

For example, the expression

(1..100).reduce(plus)

results in the integer 5050.

Returns [].

Produce a new sequence containing all elements of this stream that satisfy the given predicate function, in the order in which they occur in this stream.

This operation is an eager counterpart to Iterable.filter(). For any stream it, and predicate p:

it.select(p) == [*it.filter(p)]

Returns [].

Produces a stream containing the elements of this stream, after skipping the first skipping elements produced by its iterator.

If this stream does not contain more elements than the specified number of elements to skip, the resulting stream has no elements. If the specified number of elements to skip is zero or fewer, the resulting stream contains the same elements as this stream.

Produces a stream containing the elements of this stream, after skipping the leading elements until the given predicate function returns false.

Return two lists, the first containing the elements that occur before the given index, the second with the elements that occur after the given index. If the given index is outside the range of indexes of this list, one of the returned lists will be empty.

For any list, and for any integer index:

list.slice(index) == [list[...index-1], list[index...]]

This is an eager operation.

Produce a new sequence containing the elements of this stream, sorted according to the given comparator function imposing a partial order upon the elements of the stream.

For convenience, the functions byIncreasing() and byDecreasing() produce suitable comparator functions.

For example, this expression

"Hello World!".sort(byIncreasing(Character.lowercased))

evaluates to the sequence [ , !, d, e, H, l, l, l, o, o, r, W].

This operation is eager by nature.

Note that the toplevel function sort() may be used to sort a stream of Comparable values according to the natural order of its elements.

Returns [] for any given span.

Returns [] for any given span.

Returns [] for any given span.

Given a method() of the element type Element, return a function that, when supplied with a list of method arguments, produces a new iterable object that applies the method to each element of this iterable object in turn.

{Boolean+}(Object) fun = (-1..1).spread(Object.equals);
print(fun(0)); //prints { false, true, false }

A sublist of this list, starting at the element with index from, ending at the element with the index to.

This is a lazy operation, returning a view of this list.

A sublist of this list, starting at the element with the given index.

This is a lazy operation, returning a view of this list.

A sublist of this list, ending at the element with the given index.

This is a lazy operation, returning a view of this list.

Produces a stream containing the first taking elements of this stream.

If the specified number of elements to take is larger than the number of elements of this stream, the resulting stream contains the same elements as this stream. If the specified number of elements to take is fewer than one, the resulting stream has no elements.

Produces a stream containing the leading elements of this stream until the given predicate function returns false.

Select the last elements of the list, returning a list no longer than the given length. If this list is shorter than the given length, return this list. Otherwise return a list of the given length.

For any list, and for any integer length:

list.terminal(length) == list[size-length...]

This is an eager operation.

Trim the elements satisfying the given predicate function, along with any null elements, from the start and end of this list, returning a list no longer than this list.

This is an eager operation.

Trim the elements satisfying the given predicate function, along with any null elements, from the start of this list, returning a list no longer than this list.

This is an eager operation.

Trim the elements satisfying the given predicate function, along with any null elements, from the end of this list, returning a list no longer than this list.

This is an eager operation.

Returns [].

Returns a new sequence that starts with the specified element, followed by the elements of this sequence, in the order they occur in this sequence.

Returns a new sequence that starts with the elements of this sequence, in the order they occur in this sequence, and ends with the specified element.