Experiment with alternative syntax to ?? and ? :

gistfile1.cs

public int Floor(int value)
{
    return value.Unless(v => v < 0, () => 0);
}

public static T Unless<T>(this T obj, Func<T, bool> term, Func<T> result)
{
    if (term(obj))
        return result();

    return obj;
}

// alternatively

public int Floor(int value)
{
    return value.Unless(that: v => v < 0, then: 0);
}

public static T Unless<T>(this T obj, Predicate<T> that, T then)
{
    if (that(obj))
        return then;

    return obj;
}