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firstValue

Note

This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information.

Returns the first value in the current ImmSet

public function firstValue(): ?Tv;

This method is interchangeable with firstKey().

Returns​

  • ?Tv - The first value in the current ImmSet, or null if the current ImmSet is empty.

Examples​

See Set::firstValue for usage examples.