A quick bloom filter in Rx

gistfile1.cs

public static IObservable<Tuple<TSource, bool>> Bloom<TSource>(this IObservable<TSource> source, int size)
{
	BitArray bitmap = new BitArray(size);

	return source.Select<TSource, Tuple<TSource, bool>>(value =>
	{
		var hashCode = value.GetHashCode();
		var tuple = new Tuple<TSource, bool>(value, bitmap[hashCode] == true);
		bitmap[hashCode] = true;
		return tuple;
	});
}