语法错误 OCaml

Question

我开始在 OCaml 中编写此代码，以获取文件中每个字符的计数。

open Hashtbl;;

type 'a option = None | Some of 'a;;

let rec charCount fd ht =
  let x = 
    try Some (input_char fd)
    with End_of_file -> None
  in
  match x with
  | Some c -> 
    let val = 
      try find (ht c)
      with Not_found -> 0
    in
    replace ht c (val+1);
    charCount fd ht
  | None -> ();;

let ht = create 0;;

let loadHisto fn = 
  let fd = open_in fn 
  in 
  charCount fd ht;;
  loadHisto "testfile";;
  iter printf("%s => %s\n") ht;;

当我尝试使用 ocamlc -c 编译它时，我收到了消息：

Error: Syntax error:

Answer 1

val是保留字，不能使用