Ugh, I'm past the edit time. Of course one wouldn't expect `(is (+ l) (join l))` to be 't, because that's the definition of 'is. (even `(is (list 1) (list 1))` returns 'nil). But the second part is bad, I think: the elements inside l should stay the same.
I blame not really hacking in Arc much lately. I haven't really been up for programming much of anything.
"But the second part is bad, I think: the elements inside l should stay the same."
I agree. I really think this is a simple coding mistake in ac.scm. I talk more about this here, a reply to that thread you linked to: http://arclanguage.org/item?id=17114
I completely forgot about this difference between + and 'join after that thread, and I don't remember encountering it before that either. How fitting it's a testing framework that brings this bug to the surface! :-p
