用OCaml计算欧拉常数

let rec factorial n =
  if n <= 1 then 1
  else n * factorial (n - 1)

let euler_constant n =
  let sum = ref 1.0 in
  for i = 1 to n do
    let term = 1.0 /. float_of_int (factorial i) in
    sum := !sum +. term
  done;
  !sum

let () =
  let n = 10 in
  let result = euler_constant n in
  print_endline ("Euler's constant with " ^ string_of_int n ^ " terms: " ^ string_of_float result)