`map` lazy evaluation



In [1]:

    
def f(x):
    return x % 2



In [2]:

    
%%timeit

m = map(f, range(1000))









    



462 ns ± 38.4 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)



In [3]:

    
%%timeit

for m in map(f, range(1000)):
    pass









    



98.7 µs ± 4.19 µs per loop (mean ± std. dev. of 7 runs, 10000 loops each)

calling `map` on a 10 times longer sequence takes roughly 10 times longer



In [4]:

    
%%timeit

for m in map(f, range(10000)):
    pass









    



941 µs ± 7.25 µs per loop (mean ± std. dev. of 7 runs, 1000 loops each)