Interface Traversable<A>

interface Traversable<A extends Type> {
    get isEmpty(): boolean;
    get size(): number;
    ap<B extends unknown>(ff: Applicative<(value: A) => B>): Applicative<B>;
    contains(value: A): boolean;
    flatMap<B extends unknown>(f: (value: A) => Monad<B>): Monad<B>;
    flatMapAsync<B extends unknown>(
        f: (value: A) => PromiseLike<AsyncMonad<B>>,
    ): PromiseLike<AsyncMonad<B>>;
    map<B extends unknown>(f: (value: A) => B): Functor<B>;
    reduce(f: (b: A, a: A) => A): A;
    reduceRight(f: (b: A, a: A) => A): A;
}