Ocaml表达式类型混淆

我编写了这个ocaml函数:

(* int Base.List.t -> Base.Int.t x Base.Int.t *)
let min_and_max lst =
  let mmax = ref Float.neg_infinity
  and mmin = ref Float.infinity in
    List.iter ~f:(fun v -> let fv = Float.of_int v in 
                  if fv > !mmax then mmax := fv
                  else if fv < mmin then mmin := fv)
              lst;
    (Int.of_float !mmin, Int.of_float !mmax)

File "02-exercises/24-refs/problem.ml", line 25, characters 21-23:
Error: This expression has type Base.Float.t = float
       but an expression was expected of type int

错误指向第一个 if

考虑到目前为止的答案和评论的解决方案:

let min_and_max lst =
  match lst with
  | [] -> failwith "Cannot find min and max of empty list"
  | v::[] -> (v,v)
  | a::b::rest -> 
    let mmax = ref (max a b)
    and mmin = ref (min a b) in
      List.iter ~f:(fun v -> 
                      if v > !mmax then mmax := v;
                      if v < !mmin then mmin := v)
                rest;
      (!mmin, !mmax)