@monstermann/fn/dist/map/mapOrThrow.d.ts

A utility library for TypeScript.

import { MapMap } from "./internals/types.js";

//#region src/map/mapOrThrow.d.ts

/**
 * `mapOrThrow(map, key, transform)`
 *
 * Transforms the value at `key` in `map` using `transform`, throwing an error if the key doesn't exist.
 *
 * ```ts
 * mapOrThrow(
 *     new Map([
 *         ["a", 1],
 *         ["b", 2],
 *     ]),
 *     "a",
 *     (value) => value * 2,
 * ); // Map(2) { "a" => 2, "b" => 2 }
 *
 * mapOrThrow(
 *     new Map([
 *         ["a", 1],
 *         ["b", 2],
 *     ]),
 *     "c",
 *     (value) => value * 2,
 * ); // throws FnError
 * ```
 *
 * ```ts
 * pipe(
 *     new Map([
 *         ["a", 1],
 *         ["b", 2],
 *     ]),
 *     mapOrThrow("a", (value) => value * 2),
 * ); // Map(2) { "a" => 2, "b" => 2 }
 *
 * pipe(
 *     new Map([
 *         ["a", 1],
 *         ["b", 2],
 *     ]),
 *     mapOrThrow("c", (value) => value * 2),
 * ); // throws FnError
 * ```
 */
declare const mapOrThrow: {
  <K, V>(key: NoInfer<K>, transform: MapMap<K, V>): (target: Map<K, V>) => Map<K, V>;
  <K, V>(key: NoInfer<K>, transform: MapMap<K, V>): (target: ReadonlyMap<K, V>) => ReadonlyMap<K, V>;
  <K, V>(target: Map<K, V>, key: NoInfer<K>, transform: MapMap<K, V>): Map<K, V>;
  <K, V>(target: ReadonlyMap<K, V>, key: NoInfer<K>, transform: MapMap<K, V>): ReadonlyMap<K, V>;
};
//#endregion
export { mapOrThrow };