alt Hacker NewsNah. It involves multiple passes and setting the answer to the wrong value before (hopefully) setting it to the right value.
Plus it forces you out of whatever lazy/streaming paradigm you had going on. If your foldr produces a list, downstream can start consuming it in constant memory as long as you let it do its thing.
fold kinda does too, for setting the first combined value that you are assembling, and thus on an empty list you end up with that wrong value, same as the for loop