fun sum (t ::: Type) (_ : num t) (fs ::: {Unit}) (fl : folder fs) (x : $(mapUT t fs)) = foldUR [t] [fn _ => t] (fn (nm :: Name) (rest :: {Unit}) [[nm] ~ rest] n acc => n + acc) zero [fs] fl x fun main () = return {[sum (Folder.cons [#A] [()] ! (Folder.cons [#B] [()] ! Folder.nil)) {A = 0, B = 1}]}
{[sum (Folder.cons [#D] [()] ! (Folder.cons [#C] [()] ! (Folder.cons [#E] [()] ! Folder.nil))) {C = 2.1, D = 3.2, E = 4.3}]}