The future of Python immutability

[Terry Reedy]

Adam Skutt wrote:
\
>> This is a side-effect of writing code that relies on global variables.
>> Global variables are generally a bad idea. Global constants are fine.
> 
> Nope, the variables don't have to be global to have this problem, they
> just have to be shared:
> 
>     >>> a = 3
>     >>> b = lambda x: x + a

This is a pointless replacement for 'def b(x): return x+a'

>     >>> print b(3)
>     6
>     >>> a = 4
>     >>> print b(3)
>     7
> 
> Passing any lambda

Python does not have lambda objects. It has lambda expressions that 
produce function objects identical except for .__name__ to the 
equivalent def statement output.

tjr