is-single

array →
is-single() → boolean

Returns whether the input array contains exactly one element. Returns false when the input cannot be evaluated as an array.

Parameters

This predicate has no parameters.

Behavior

Cardinality is independent of element values: a sole null, array, or record counts as one element. Uses the same array conversion as single, including text containing an Expressif array literal. When is-single returns true, single returns the sole element.

Examples

{42} | is-single → #true
{} | is-single → #false
{1, 2} | is-single → #false
{#null} | is-single → #true

Kind: Predicate
Scope: array
Aliases: None