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. :::

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

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

map()'s result contains a value for every value in the current ImmVector; unlike filter(), where only values that meet a certain criterion are included in the resulting ImmVector.

Guide

• Examples

Parameters

• (function(Tv): Tu) $callback

Returns

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

Examples

See Vector::map for usage examples.