Syntax

	$setOfSets.flatten()

Description

Calculates a set that contains all elements from all element sets in the set setOfSets.

Two-dimensional sets (i.e. sets that contain sets as elements again) are not supported as final result. Therefore, all elements in the inner sets must be unpacked and stored as elements of the outer set instead. One therefore needs flatten() for example when $set.map($func) (see Map) is called and func itself returns a set.

Parameter

Name	Type	Description	Mandatory	Default
setOfSets	Set	A two-dimensional set (set with sets as elements).	yes

Return Value

Type: Set

A set containing all the individual elements of the original set elements.

Examples

Simple two-diemnsional set

	list(1, 4, 9)
  .map(x -> concat($x, 2, 3))
  .flatten()

Output: A set with the elements [1, 2, 3, 4, 2, 3, 9, 2, 3].

The elements of the three result sets [1, 2, 3], [4, 2, 3], and [9, 2, 3] are unwrapped and inserted as elements of a single set.

Set-valued reference attributes

Assuming that the type my.module:MyTyp has a set-valued reference attribute others, then the expression

all(`my.module:MyType`)
  .map(x -> $x.get(`my.module:MyType#others`)

would return a set of sets with all objects referenced in others, which is not supported as the end result of, for example, a search. Therefore, the result set must be flattened:

all(`my.module:MyType`)
  .map(x -> $x.get(`my.module:MyType#others`)
  .flatten()