YAML Sets

YAML Sets

YAML Set (!!set) is an unordered set of non-equal values.

note

Note that a set is an unordered collection of nodes such that no two nodes are equal.

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YAML Sets are a kind of mapping, so the !!set tag may be given explicitly.

Alternatively, the application may choose to implicitly type mappings with all-null values to sets. In this case, an explicit !!map transfer must be given to mappings that have all-null values but do not represent sets.

For example:

baseball-players: !!set
  ? Tom Nolan
  ? Ryan Raynolds
  ? John Smith

Another example:

set1: !!set
  ? one
  ? two
set1: !!set
  ? three
  ? four

Equivalent JSON

{
  "set1": {"one": null, "two": null},
  "set2": {"three": null, "four": null}
}

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You can also use the flow style to define a set

my-set: !!set {'one', "two"}