import { HVal } from 'haystack-core';
export declare const HS_ACCEPT_HEADER_VALUE: string;
export interface FetchMethod {
    (resource: RequestInfo, options?: RequestInit | undefined): Promise<Response>;
}
/**
 * Validate the HTTP response object.
 *
 * @param resp The response to validate.
 * @param val The associated value.
 * @throws Error if the response is invalid.
 */
export declare function validateResponse(resp: Response, val?: unknown): void;
/**
 * Make some haystack value options.
 *
 * @param options The fetch options.
 * @returns The updated fetch optons.
 */
export declare function makeHsOptions(options?: RequestInit): RequestInit;
/**
 * Convience method to fetch a haystack value from the server.
 *
 * If the returned value is a grid and has an error then the returned promise
 * will be rejected with a `GridError` instance.
 *
 * @param resource The resource to request.
 * @param options Optional object containing any custom settings.
 * @param fetchFunc Optional fetch function to use instead of global fetch.
 * @returns A promise that resolves to a value.
 * @throws A fetch or grid error.
 */
export declare function fetchVal<T extends HVal>(resource: RequestInfo, options?: RequestInit, fetchFunc?: FetchMethod): Promise<T>;