public class DefaultEither<A,B> : Either<A,B> {
	private A theA;
	private B theB;

	public DefaultEither(A _theA, B _theB){
		theA = _theA;
		theB = _theB;
	}

	public static DefaultEither<A,B> newA(A _theA)
	{
		return new DefaultEither<A,B>(_theA,default(B));
	}

	public static DefaultEither<A,B> newB(B _theB)
	{
		return new DefaultEither<A,B>(default(A),_theB);
	}
		
	public A a()
	{
		return theA;
	}


	public bool isA()
	{
		return theA != null;
	}


	public B b()
	{
		return theB;
	}


	public bool isB()
	{
		return theB != null;
	}

	public Either<A, B> fmap(System.Func<B, B> f) {
		if (isA ()) {
			return this;
		}
		return newB(f(b()));
	}

	public Either<A, B> bind (System.Func<B, Either<A, B>> f) {
		if (isA ()) {
			return this;
		}

		return f (b ());
	}
}