**reduce‑map** is a tiny utility that turns a regular reducer function into a “reducing map” – a function that, when used in a `reduce` call, applies the reducer to each element of a container (object or array) and returns a new container of the same shape with the updated items. It’s aimed at JavaScript developers working with immutable state patterns (e.g., Redux or Redux‑like reducers) who want a concise way to map updates over collections within their reducers.