Thanks Brent, this should do the trick, although what I was asking was something more general:
For "explicitly pass" I meant passing them without the eta reduce, in other terms:
swapA' :: (Arrow a) => a ((b,c), (b,c)) (c,b)
swapA' t = (????) swapFirst >>> swapSecond (???)
where
swapFirst = first $ arr snd
swapSecond = second $ arr fst
where the question marks indicate that I don't know how to tell swapFirst "hey, even though from the outside
I'm passing you a tuple *t*, you have to take as input a (t,t)."
Hope this is clearer or it has some sense at all, maybe I'm not getting correctly the way arrows work!
bye,
A.