Map

:::info[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 map<Tu>(
  (function(Tv): Tu) $fn,
): Iterable<Tu>;

Parameters

• (function(Tv): Tu) $fn

Returns

• Iterable<Tu>