lambda is slower than function call in python, why

Question

I think lambda is faster than function call, but after testing, I find out that I am wrong. Function call is definitely faster than lambda call.

Can anybody tell me why

Answer 1

As pointed out above, your first test only profiles the time it takes to define a. It's actually never called.

Lambda expressions and "normal" functions generate the exact same bytecode, as you can see if you use the dis module:

def a(): return 10
b = lambda: 10

import dis

>>> dis.dis(a)
1           0 LOAD_CONST               1 (10)
            3 RETURN_VALUE
>>> dis.dis(b)
1           0 LOAD_CONST               1 (10)
            3 RETURN_VALUE