replacing defs with lambda expressions python 3.3

Question

i'm new to programming but im stuck with a question, which im asking myself. I made an example like this:

u = 1

def method1(x):
    def method2(n):
        def method3(m):
            return x + n + m
        def method4():
            global u
            u += 1
        method4()
        return method3
    def method5(y):
        return x + y
    return method2, method5

The question is: Can I replace some of these defintions with lambda expressions? I dont want to change the semantics of the code above. I was thinking about something like this:

u = 1
def method1(x):
    def method2(n):
        lambda m: x + n + m
        def method4():
            global u
            u += 1
        method4()
    lambda y: x + y
    return method2

If this what i have done is correct, can i replace even more definitions without changing the semantics of the code or am I wrong?

Answer 1

It is not completely correct since you do not store the lambda expressions nor do you return them. A semantically equivalent program should be:

u = 1

def method1(x):
    def method2(n):
        method3 = lambda m: x + n + m
        def method4():
            global u
            u += 1
        method4()
        return method3
    method5 = lambda y: x + y
    return method2, method5

can i replace even more definitions without changing the semantics

I think unless you make the program totally unreadable, this is about it. Mind however that you do not have to transform all functions into lambda expressions: it is simply useful and can sometimes improve readability. But it should not be a goal by itself.

Note: like @juanpa.arrivillaga says it is however not recommended to store lambda expressions into variables, etc. It is against style guidelines. It is not semantically incorrect, but is not considered good coding.