public IValue Subtract(Context context, IValue value)
{
if (value is ListValue)
{
SetValue set = new SetValue(this.ItemType);
value = set.Add(context, value);
}
if (value is SetValue)
{
ListValue result = new ListValue(ItemType);
result.AddRange(this);
result.RemoveAll(item => ((SetValue)value).HasItem(context, item));
return(result);
}
else
{
throw new SyntaxError("Illegal : List - " + value.GetType().Name);
}
}