Skip to main content

mapWithKey

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.

public function mapWithKey<Tu>(
  (function(Tk, Tv): Tu) $fn,
): KeyedIterable<Tk, Tu>;

Parameters​

  • (function(Tk, Tv): Tu) $fn

Returns​