minigent/examples/6_recursive/08-list-sum/in.minigent

sumList : rec t { l: < Nil Unit | Cons { data: U32, rest: t! }# >}! -> U32;
sumList r = 
  take r2 { l = z } = r in
    case z of
      Nil u -> 0
    | v2 -> 
      case v2 of
        Cons s ->
          take s2 { rest = x } = s in
            s.data + sumList x
          end
      end
    end
  end;