When two languages have different scoping rules, they don't have the same semantics.
When two languages differ in their opinion about macros, they don't have the same semantics.
When two languages have different semantics, they are different languages.
And finally, when two languages have fundamentally different syntaxes, the idioms promoted by their creators differ, and thus problems are solved in different ways.
Erlang and Elixir aren't the same language, but they do share a pretty unique architecture in OTP. When people talk about "the advantages of Erlang" they're frequently really talking about OTP (that, or BEAM's reduction-counting ISA.) So people think it's Erlang that gives you those advantages.
Of course, it's not; any language that targets BEAM could pick up those advantages "for free", in the same way Clojure gets a bunch of Java libraries "for free." But people compare programming languages, not abstract machines or library ecosystems. If you treat Erlang and Elixir as black boxes, hiding BEAM and the OTP (the way someone who doesn't know either language would), then they seem to be much more similar to one-another than any other language is to either of them.
I wouldn't call it "scoping" difference, although I can see why one would think about it as such. It would be a real scoping issue if you could assign variables in outer scopes from inside the nested scopes. Can you?
> what I mentioned is still different scoping rules
You're probably right, I don't want to argue about terminology.
What do you mean by "scare quotes"? Honest question: English is my second language and I'm not very good with it.
> You can.
You're wrong. Here, take a look:
iex(4)> f = fn() -> a = 0; (fn()->a=9 end).(); a end
#Function<20.80484245/0 in :erl_eval.expr/5>
iex(5)> f.()
0
f.() should evaluate to 9 if what you said was true. Either there's a special syntax for doing this in Elixir (like nonlocal in Python 3) or it's absent, and then the scoping rules are the same in Elixir and Erlang, with a bit of syntactic sugar for SSA transformation, which you need to do by hand in Erlang.
Again, I'm not Elixir programmer, so this is a honest question: is there some special syntax which would make the example above produce 9? I doubt it very much because it wouldn't fit very well with BEAM, but everything is possible and I'd be glad to learn about another nice feature of Elixir.
You introduced a closure there. Bindings set in if, case, receive, etc will spill in their surrounding environment. Obviously they won't spill outside closures without mutable terms, which BEAM lacks.
The bits about SSA transformation needed to be done by hand in Erlang are a bit fun, because that's considered a feature in the Erlang realm.
The scoping rules aren't the same for the very reason you dismiss as an implementation detail.
> The scoping rules aren't the same for the very reason you dismiss as an implementation detail.
Ok, this means that I need to learn some more about how scoping rules are defined and described, because apparently my current understanding is incompatible with the common one. That happens all the time if you're self-taught like me, so I simply accept this.
Thanks for discussion and the "scare quotes" term :)
When two languages have different semantics, they are different languages.
And finally, when two languages have fundamentally different syntaxes, the idioms promoted by their creators differ, and thus problems are solved in different ways.
They are not fundamentally the same language, no.