/** Grainlet reactive primitives */

export type Accessor<T> = () => T;

export type Setter<T> = {
  (value: T): void;
  (updater: (prev: T) => T): void;
};

export type Signal<T> = [get: Accessor<T>, set: Setter<T>];

export declare function createSignal<T>(): Signal<T | undefined>;
export declare function createSignal<T>(initialValue: T): Signal<T>;

export declare function createEffect(fn: () => void | (() => void)): () => void;

export declare function createMemo<T>(fn: () => T): Accessor<T>;

export declare function onCleanup(fn: () => void): void;
export declare function onMount(fn: () => void | (() => void)): void;

export declare function untrack<T>(fn: () => T): T;
export declare function batch<T>(fn: () => T): T;
export declare function startTransition(fn: () => void): Promise<void>;
export declare function useTransition(): [
  pending: Accessor<boolean>,
  start: typeof startTransition,
];
export declare function createDeferred<T>(
  source: Accessor<T>,
  options?: { timeoutMs?: number }
): Accessor<T>;

export declare function isServer(): boolean;