merge 2 dictionaries in python

merge.py

# dict1 : {
#     "a" : 1,
#     "b" : "3",
#     "c" : (4,),
#     "d" : [3],
#     "e" : {"f" : 7},
# }
# dict2 : {
#     "a" : 2,
#     "b" : "4",
#     "c" : (3,),
#     "d" : [7],
#     "e" : {"g" : 8},
# }

def type_of(val1: any, val2: any):
    types = [int, str, tuple, list, dict]
    fst_type_list = map(lambda type: (isinstance(val1, type), type), types)
    snd_type_list = map(lambda type: (isinstance(val2, type), type), types)

    return [fst[1] for (fst, snd) in
            zip(fst_type_list, snd_type_list) if (fst[0] and snd[0])][0]


def merge(dict1: dict, dict2: dict) -> dict:
    switch = {
        int: lambda a, b: a + b,
        str: lambda a, b: a + b,
        tuple: lambda a, b: a + b,
        list: lambda a, b: a + b,
        dict: lambda a, b: merge(a, b)}

    key_set1 = set(dict1.keys())
    key_set2 = set(dict2.keys())
    common_keys = key_set1.intersection(key_set2)
    disjoint_key1 = key_set1.difference(key_set2)
    disjoint_key2 = key_set2.difference(key_set1)

    updated_dict = dict(
        (k, switch[type_of(dict1[k], dict2[k])](dict1[k], dict2[k]))
        for k in common_keys
    )

    disjoint_dict1 = dict((k, dict1[k]) for k in disjoint_key1)
    disjoint_dict2 = dict((k, dict2[k]) for k in disjoint_key2)
    disjoint_dict = dict(**disjoint_dict1, **disjoint_dict2)

    updated_dict = dict(**updated_dict, **disjoint_dict)

    return updated_dict


def main():

    dict1 = {
        "a": 1,
        "b": "3",
        "c": (4,),
        "d": [3],
        "e": {"f": 7},
    }

    dict2 = {
        "a": 2,
        "b": "4",
        "c": (3,),
        "d": [7],
        "e": {"f": 6, "g": 8},
    }

    print(merge(dict1.copy(), dict2.copy()))


main()