Support collections.Counter ?

[paugier]

https://docs.python.org/3.8/library/collections.html#collections.Counter can be very useful in numerical kernels.

Since they are very similar to dict, it may be not too difficult to implement, especially a simplified version without the extra methods elements, most_common, ... ?

Without Counter, one needs to replace

def main_not_supported(...):
    ...
    counter = Counter()
    print(counter["foo"])
    counter["bar"] += 1
    ...

by something like:

def increment_counter(counter, key):
    try:
        counter[key] += 1
    except KeyError:
        counter[key] = 1

def get_counter_value(counter, key):
    try:
        return counter[key]
    except KeyError:
        return 0

def main(...):
    counter = {}
    print(get_counter_value(counter, "foo"))
    increment_counter(counter, "bar")

[serge-sans-paille]

I agree this would be a valuable addition. Needs some time to do it though :-)