Serialize Memoize Param

:::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. :::

Takes an argument to a function marked with <<__Memoize>> and serializes it to a string usable as a unique cache key

namespace HH;

function serialize_memoize_param(
  mixed $param,
): arraykey;

This works with all builtin types and with objects that implement the HH\IMemoizeParam interface

Parameters

• mixed $param

Returns

• arraykey