Hash

declare function isHash(u: unknown): u is Hash;

declare function array<A>(arr: readonly Array<A>): number

declare const cached: {
  (self: object): (hash: number) => number;
  (self: object, hash: number): number;
};

declare const combine: (b: number) => (self: number) => number;

declare const hash: <A>(self: A) => number;

declare function number(n: number): number;

declare function optimize(n: number): number;

declare const random: <A extends object>(self: A) => number;

declare function string(str: string): number;

declare function structure<A extends object>(o: A): number;

declare function structureKeys<A extends object>(o: A, keys: readonly Array<keyof A>): number

interface Hash {
  [symbol](): number;
}

declare const symbol: unique symbol;