/**
 * Union of every primitive value type. Matches the values for which
 * `box.isPrimitive()` returns `true` and the type `BaseBox.isPrimitive()`
 * narrows to. Functions and non-null objects are excluded; `null` and
 * `undefined` are included since ECMAScript classifies both as primitives.
 */
export type PrimitiveType = string | number | bigint | boolean | symbol | null | undefined;

/** Broadest function shape. Every function is assignable to `UnknownFn`. */
export type UnknownFn = (...args: never[]) => unknown;

// Intersect all extracted M types.
export type IntersectAll<T extends readonly unknown[]> = T extends readonly [infer H, ...infer R]
    ? H & IntersectAll<R>
    : object;

/** True when `v` is a function. Narrows `v` to a callable type. */
// eslint-disable-next-line @typescript-eslint/no-explicit-any
export declare function isFunction(v: unknown): v is (...args: any[]) => unknown;

/** True when `v` is non-null and either an `object` or a `function`. */
export declare function isObjectLike(v: unknown): v is object;