batteries included, сказал питон

[amarao]

[[1,2], [3,4]].flatten()
               ^ ERROR: Flatten is not a battery. That's why it's not in the Python.

Comments

[juan_gandhi]

FP not available. As Guido said, he does not know categories, and has no plans to learn.

[yurikhan]

In [6]: list(itertools.chain(*[[1, 2], [3, 4]]))
Out[6]: [1, 2, 3, 4]

In [7]: list(itertools.chain.from_iterable([[1, 2], [3, 4]]))
Out[7]: [1, 2, 3, 4]

ну или в лоб:

In [8]: [x for xs in [[1, 2], [3, 4]] for x in xs]
Out[8]: [1, 2, 3, 4]