[Python-ideas] __len__() for map()

[Jonathan Fine]

Hi Kale

Thank you for the sample code. It's most helpful. Please consider

>>> it = iter(range(4))
>>> list(map(float, it))
[0.0, 1.0, 2.0, 3.0]

>>> it = iter(range(4))
>>> list(zip(it, it))
[(0, 1), (2, 3)]

>>> list(zip(range(4), range(4)))
[(0, 0), (1, 1), (2, 2), (3, 3)]

A sequence is iterable. An iterator is iterable. There are other
things that are iterable. A random number generator is an iterator,
whose underlying object does not have a length.

Briefly, I don't like your suggestion because many important iterables
don't have a length!

-- 
Jonathan