is foo += 1 considered functional?

Was thinking of creating a CONS function to create a list, but then realized that im not mutating any state with foo += 1, since its == foo = foo + 1 which is a new ob开发者_开发问答ject

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The state is changed: the value referenced with the variable foo changes.

This is "not functional" in any pure sense. I might be tempted to call it "confusing" ;-)

Happy coding.