python list

s_list.py

class Nil:

    def is_empty(self):
        return True

    def head(self):
        raise Exception("Exception: Empty list")

    def tail(self):
        raise Exception("Exception: Empty list")


class Cons:

    def __init__(self, _head, _list_tail=Nil()):
        self.head = _head
        self.tail = _list_tail

    def is_empty(self):
        return False
    
    def head():
        return self.head
    
    def tail():
        return self.head

    def __getitem__(self, index):
        return nth(index, self)

      

class ImmutableList(metaclass=ABCMeta):
    @abstractmethod
    def is_empty(self):
        pass

    def head(self):
        pass

    def tail(self):
        pass


ImmutableList.register(Nil);
ImmutableList.register(Cons)