import { ResolveCallback, ErrorCallback, ContextType } from '../shared/types';
import { Pipe } from './pipe';
export declare type ReduceFuncSync = (acc: any, cur: any) => any;
export declare type ReduceFuncAsync = (acc: any, cur: any, callback: ResolveCallback<any>, error: ErrorCallback, emissionContext: ContextType, accContext: ContextType) => void;
export declare type ReduceFunc = ReduceFuncSync | ReduceFuncAsync;
/**
 *
 * Represents [reduce](https://connective.dev/docs/reduce) pins.
 *
 */
export declare class Reduce extends Pipe {
    readonly reduce: ReduceFunc;
    readonly start: any;
    private _acc;
    /**
     *
     * @param reduce is the reduction function
     * @param start is the start value
     *
     */
    constructor(reduce: ReduceFunc, start?: any);
    private _init;
}
/**
 *
 * Creates a [reduce](https://connective.dev/docs/reduce) pin.
 * A reduce pin can be used to aggregate values over multiple emissions, with an
 * aggregator function updating the aggregate value based on each incoming emission.
 * [Checkout the docs](https://connective.dev/docs/reduce) for examples and further information.
 *
 * @param reduce the reduction function
 * @param start the start value. If not provided, the value of first incoming emission will be used.
 *
 */
export declare function reduce(reduce: ReduceFunc, start?: any): Reduce;
export default reduce;