### code.ml [ocaml]
let foldf1 =
  let foldf data accum = accum + data in
  0, foldf

let foldf2 =
  let foldf data accum = data :: accum in
  [], foldf

let () =
  let foldpairs = [foldf1; foldf2] in
  let values, foldfs = List.split foldpairs in
  let results = List.fold_left
    (fun accum data ->
      List.map2
        (fun f a -> f data a)
        foldfs
        accum)
    values
    [1; 2; 3; 4]
  in ()
### error.txt

File "pplacer_src/polymorphism_test.ml", line 10, characters 27-33:
Error: This expression has type 'a list * ('b -> 'b list -> 'b list)
       but an expression was expected of type int * (int -> int -> int)