/**
 * Symbol used to indicate that an object is an Atom
 */
declare const ATOM_SYMBOL: unique symbol;
/**
 * Symbol used to indicate that an object is a Signal
 */
declare const SIGNAL_SYMBOL: unique symbol;

/**
 * A reactive value which notifies consumers of any changes.
 *
 * Atoms are functions which returns their current value. To access the current value of an atom,
 * call it.
 */
type Atom<T> = (() => T) & {
    /** @internal */
    readonly [ATOM_SYMBOL]: unknown;
};
/**
 * An Atom that can be destroyed
 */
type DestroyableAtom<T> = Atom<T> & Readonly<{
    /**
     * Signals that the `AtomEffect` has been destroyed
     */
    readonly onDestroyed: Signal<void>;
    /**
     * Returns a readonly version of this atom
     */
    asReadonly(): Atom<T>;
    /**
     * Destroys the atom, notifies any dependents and calls `onDestroy` callback.
     */
    destroy(): void;
}>;
/**
 * Signal is an event emitter. It can be called to notify listeners of events.
 *
 * @example
 * ```ts
 * // Create the signal
 * const submitForm = signal<{login: string, password: string}>();
 *
 * // Call the signal
 * submitForm({login: 'foo', password: 'bar'});
 *
 * // Handle signal's events
 * effect(submitForm, (formData) => {
 *   // Process the formData
 * });
 * ```
 */
type Signal<Event> = {
    (event: Event): void;
    readonly [SIGNAL_SYMBOL]: unknown;
} & ([Event] extends [undefined | void] ? {
    (event?: Event): void;
} : {
    (event: Event): void;
});
/**
 * A comparison function which can determine if two values are equal.
 */
type ValueEqualityFn<T> = (a: T, b: T) => boolean;

export type { Atom as A, DestroyableAtom as D, Signal as S, ValueEqualityFn as V };