Super basic implementation of linked lists in BType

linkedList.bt

object LinkedList {
    with T;

    LinkedListNode<T>:first;
    LinkedListNode<T>:last;
    int:length;

    append(T:value) {
        var node = new LinkedListNode<T>(self, value);
        self.length = self.length + 1;

        if self.first == null {
            self.first = node;
            self.last = node;
            node.next = node;
            node.previous = node;
            return;
        }

        self.last.next = node;
        node.previous = self.last;
        self.last = node;
        node.next = self.first;
    }

    T:shift() {
        var val = self.first.value;
        self.first = self.first.next;
        self.last.next = self.first;
        return val;
    }

}


object LinkedListNode {
    with T;

    LinkedList<T>:parent;
    LinkedListNode<T>:next;
    LinkedListNode<T>:previous;
    T:value;

    new(LinkedList<T>:parent, T:value) {
        self.parent = parent;
        self.value = value;
    }

}


func int:main() {
    var ll = new LinkedList<int>();
    ll.append(1);
    ll.append(2);
    ll.append(3);

    var acc = ll.shift();
    acc = acc + ll.shift();
    acc = acc + ll.shift();

    return acc;

}
export main;