Failable Monad

Failable.java

public sealed interface Failable<A> extends CoProduct2<List<String>, A, Failable<A>>, Monad<A, Failable<?>> {
    @Override
    default <B> Failable<B> flatMap(Fn1<? super A, ? extends Monad<B, Failable<?>>> fn1) {
        return match(Failed::new, fn1.fmap(Monad::coerce));
    }

    @Override
    default <B> Failable<B> pure(B b) {
        return new Success<>(b);
    }

    @Override
    default <B> Failable<B> zip(Applicative<Fn1<? super A, ? extends B>, Failable<?>> appFn) {
        Failable<Fn1<? super A, ? extends B>> coerce = appFn.coerce();
        return match(failures -> coerce.match(otherFailures -> new Failed<>(addAll(ArrayList::new,
                                failures,
                                otherFailures)),
                        constantly(new Failed<>(failures))),
                a -> coerce.match(Failed::new,
                        fn -> new Success<>(fn.apply(a))));
    }

    record Failed<A>(List<String> failures) implements Failable<A> {
        @Override
        public <R> R match(Fn1<? super List<String>, ? extends R> fn1, Fn1<? super A, ? extends R> fn11) {
            return fn1.apply(failures);
        }
    }

    record Success<A>(A value) implements Failable<A> {
        @Override
        public <R> R match(Fn1<? super List<String>, ? extends R> fn1, Fn1<? super A, ? extends R> fn11) {
            return fn11.apply(value);
        }
    }
}