Does Python scoping rule fits the definition of lexical scoping?

Question

According to my programming language class, in a language that uses lexical scoping

The body of a function is evaluated in the environment where the function is defined, not the environment where the function is called.

For example, SML follows this behavior:

val x = 1
fun myfun () =
    x
val x = 10
val res = myfun()  (* res is 1 since x = 1 when myfun is defined *)

On the other hand, Python does not follow this behavior:

x = 1
def myfun():
    return x
x = 10
myfun()  # 10 since x = 10 when myfun is called

So why is Python described as using lexical scoping?

Answer 1

Your Python myfun is using the x variable from the environment where it was defined, but that x variable now holds a new value. Lexical scoping means functions remember variables from where they were defined, but it doesn't mean they have to take a snapshot of the values of those variables at the time of function definition.

Your Standard ML code has two x variables. myfun is using the first variable.