Use the dict constructor
d1={1:2,3:4}
d2={5:6,7:9}
d3={10:8,13:22}
d4 = reduce(lambda x,y: dict(x, **y), (d1, d2, d3))
As a function
from functools import partial
dict_merge = partial(reduce, lambda a,b: dict(a, **b))
The overhead of creating intermediate dictionaries can be eliminated by using thedict.update() method:
from functools import reduce
def update(d, other): d.update(other); return d
d4 = reduce(update, (d1, d2, d3), {})
