array.rev_foldl

Stream: new members

[Jason Orendorff]

array.rev_foldl seems like a weird name for that function. It's basically a right fold, right? Why not call it foldr?

[Jason Orendorff]

While I'm here: array.foldl has a different type signature from list.foldl, such that
a.foldl b f = a.to_list.foldl (λ x y, f y x) b