/**
 * fast O(n) non-mutating convert an array to an object with keys
 * defined by a property, dot-prop path, or extractor function
 *
 * An alternate usage exists when given an array of string or number:
 * in that case the return object maps the value to `true`. May be better
 * to use a Set for these cases.
 */
export declare function keyby(objArray: (string | number | undefined | null)[] | undefined): Record<string, boolean>;
export declare function keyby<ObjectType extends object>(objArray: ObjectType[] | undefined, key: keyof ObjectType): Record<string, ObjectType>;
export declare function keyby<ObjectType>(objArray: ObjectType[] | undefined, keyOrExtractor: string | number | symbol | ((obj: ObjectType) => string | number | undefined)): Record<string, ObjectType>;
/**
 * @deprecated use keyby()
 */
export declare const hashify: typeof keyby;