fallthrough.ml

type fruit =
  | Banana of int
  | Apple of int

let fruit_value include_banana f =
  match f with
  (* Error: The value include_banana is not an instance variable *)
  | Banana x when include_banana
  | Apple x ->
     x
  | _ -> 0
               
let rec sum_fruit include_banana vals =
  List.fold_left (fun x f -> x + fruit_value include_banana f) vals