ts-data-forge/dist/guard/is-primitive.d.mts

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/**
 * Type guard that checks if a value is a primitive type.
 *
 * This function identifies JavaScript primitive types, which are immutable data
 * types that are not objects. The primitive types are: `string`, `number`,
 * `boolean`, `undefined`, `symbol`, `bigint`, and `null`.
 *
 * **Important Note:** Although `null` has `typeof null === "object"` due to a
 * historical JavaScript quirk, this function correctly identifies `null` as a
 * primitive value.
 *
 * **Type Narrowing Behavior:**
 *
 * - Narrows the input type to `Primitive` (union of all primitive types)
 * - Excludes object types, arrays, functions, and other non-primitive values
 * - Includes `null` despite its misleading `typeof` result
 *
 * @example
 *
 * ```ts
 * const values: readonly unknown[] = [42, 'Ada', null, { id: 1 }] as const;
 *
 * const primitives = values.filter(isPrimitive);
 *
 * assert.deepStrictEqual(primitives, [42, 'Ada', null]);
 * ```
 *
 * @param u - The value to check
 * @returns `true` if `u` is a primitive type, `false` otherwise. When `true`,
 *   TypeScript narrows the type to `Primitive`.
 */
export declare const isPrimitive: (u: unknown) => u is Primitive;
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