How to write this python snippet in functional programming style?

Question

How can I write the line below in functional python using e.g. toolz?

dct1 = {1: 1, 2: 2}
dct2 = {2:2}
dct3 = {2:2, 3:3}

common_keys = set(dct1.keys()) & set(dct2.keys()) & set(dct3.keys())

Answer 1

If you want to try to write this in a functional style:

from functools import reduce

dct1 = {1: 1, 2: 2}
dct2 = {2: 2}
dct3 = {2: 2, 3: 3}

shared_keys = reduce(set.intersection, map(set, map(dict.keys, [dct1, dct2, dct3])))

First we create a list of the dictionaries.

Then we map the dict.keys function to each of them.

Then we map them to set giving us sets of keys for each dictionary.

Finally, we reduce those sets with the set.intersection function.