/** Options for creating an eager reactive effect. */
export interface CreateEffectOptions<Init> {
    /** The initial input passed to the first execution instead of `undefined`. */
    initial?: Init;
}
/**
 * Callback context passed to an effect execution.
 */
export interface EffectContext<Value> {
    /** The previous effect result or the configured initial input. */
    previous: Value;
    /**
     * Registers cleanup work to run before the next effect execution and when the effect is disposed.
     *
     * @param cleanup - The cleanup callback.
     */
    onCleanup(cleanup: () => void): void;
}
/**
 * Handle returned by {@link createEffect} for manual disposal.
 */
export interface Effect extends Disposable {
}
/**
 * Effect callback receiving the previous return value and cleanup registrar through a context object.
 *
 * @param context - The effect execution context.
 * @returns The next effect result.
 */
export type EffectFunction<Previous, Next> = (context: EffectContext<Previous | Next>) => Next;
/**
 * Creates an eager reactive effect.
 *
 * The effect runs immediately once and then reruns synchronously whenever one of the dependencies read during its last execution changed.
 *
 * The return value of each execution is passed into the next execution as `context.previous`. When `options.initial` is set, the first
 * execution receives that value instead of `undefined`.
 *
 * `context.onCleanup` registers callbacks that run before the next execution and when the effect is disposed.
 *
 * Effects return an explicit handle for manual disposal and additionally register their cleanup on the active scope, if there is one.
 *
 * @param func    - The effect body to execute.
 * @param options - Optional effect behavior overrides.
 * @returns An effect handle for manual disposal.
 */
export declare function createEffect<Next>(func: EffectFunction<undefined, Next>, options?: CreateEffectOptions<undefined>): Effect;
export declare function createEffect<Init, Next>(func: EffectFunction<Init, Next>, options: CreateEffectOptions<Init> & {
    initial: Init;
}): Effect;