A LinkedTuple is a read-only structure of linked (nested) tuples much like lists in functional languages.

Instances have a head element that can be anything and a tail element that can be either another LinkedTuple or None.

Being a nested container of elements, a LinkedTuple is less efficient than a list or a plain tuple, but its main advantage is that it allows branching. That is, a tail can be shared by more than one LinkedTuple

Install using pip

pip install linkedtuple

Class

• LinkedTuple(head[,tail])

  Returns a new LinkedTuple instance with the provided head and possibly a tail

Properties

• head

  read only head

• tail

  read only tail

Methods

• make(iterable) [classmethod]

  Returns a new LinkedTuple chain with the elements taken from the iterable

• plus(element)

  Returns a new LinkedTuple with element as head and the current ListTuple as tail

• reversed()

  Returns a new LinkedTuple with the items in reverse order

Examples

We can create a LinkedTuple with a single element

>>> from linkedtuple import LinkedTuple

>>> LinkedTuple('x')
LinkedTuple(head='x', tail=None)

Or from an iterable.

>>> ltup = LinkedTuple.make([1,2,3,4])

>>> ltup
LinkedTuple(head=4, tail=LinkedTuple(head=3, tail=LinkedTuple(head=2, tail=LinkedTuple(head=1, tail=None))))

Note the elements are present in reverse order.

So far, we've shown LinkedTuples as represented when calling repr() on them. When casting to string we get a more compact representation.

>>> repr(ltup)
'LinkedTuple(head=4, tail=LinkedTuple(head=3, tail=LinkedTuple(head=2, tail=LinkedTuple(head=1, tail=None))))'

>>> str(ltup)
'(4,(3,(2,(1,None))))'

LinkedTuples have a few available read-only properties, the most important ones are head and tail.

>>> ltup.head
4

>>> ltup.tail
LinkedTuple(head=3, tail=LinkedTuple(head=2, tail=LinkedTuple(head=1, tail=None)))

Passing an iterable as a single element to LinkedTuple won't expand the iterable and will result in a LinkedTuple with the iterable as head and no tail.

>>> LinkedTuple([1,2,3,4])
LinkedTuple(head=[1, 2, 3, 4], tail=None)

We can create a new LinkedTuple from an existing one plus a new element.

>>> str(ltup.plus('X'))
'(X,(4,(3,(2,(1,None)))))'

The previous one doesn't (and can't) change. LinkedTuples are immutable.

>>> str(ltup)
'(4,(3,(2,(1,None))))'

>>> ltup.head = 8
Traceback (most recent call last):
	File "<stdin>", line 1, in <module>
AttributeError: can't set attribute

We can ask for the number of elements in a LinkedTuple, however this is slow because all the chain has to be traversed to count them.

>>> print(len(ltup))
4

LinkedTuples are iterables themselves, so we can do things like the following:

>>> list(ltup)
[4, 3, 2, 1]

>>> for item in ltup:
...     print(item)
... 
4
3
2
1

We can generate a new LinkedTuple from another LinkedTuple with the elements reversed

>>> str(ltup)
'(4,(3,(2,(1,None))))'

>>> str(ltup.reversed())
'(1,(2,(3,(4,None))))'

Contact

• Me on GitHub Gato-X
• Project page on GitHub
• If you find any issues, please let me know here