MapWithKey - Hhvm — ContextQMD

:::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. :::

Returns an ImmVector containing the results of applying an operation to each key/value pair in the current ImmVector

Hack

public function mapWithKey<Tu>(
  (function(int, Tv): Tu) $callback,
): ImmVector<Tu>;

mapWithKey()'s result contains a value for every key/value pair in the current ImmVector; unlike filterWithKey(), where only values whose key/value pairs meet a certain criterion are included in the resulting ImmVector.

Parameters

(function(int, Tv): Tu) $callback

Returns

ImmVector<Tu> - An ImmVector containing the results of applying a user-specified operation to each key/value pair of the current ImmVector in turn.

Examples

See Vector::mapWithKey for usage examples.