OCaml - Parsing

Question

Got a problem with this line, here's what I want: - I enter (while executing) -g 0, my function associated to g is disabled - I enter -g 1 (or any number) my function is enabled

Exemple of what I'd like to enter:

./main.ml -g 1

My part of Code:

let greytf = ref 0 in

(...)

 let parse_command =
[("-g", if Arg.Int () <> 0 then (( greytf := 1)) else (greytf := 0) , "Enable I\
mage To Grey Mode");]

Thanks in advance

Answer 1

Boolean references are better suited for "flag" options:

let _ =
    let a_flag = ref false in
    let b_flag = ref false in
    let opt = [
        ("-a", Arg.Set a_flag,
            " This is a a flag");
        ("-b", Arg.Set b_flag,
            " This is a b flag")
    ] in
    Arg.parse
        (Arg.align opt)
        (fun a -> raise (Arg.Bad ("Bad argument: " ^ a)))
        "Usage: usage message";
    (* flag tests *)
    Printf.printf "A flag: %b\n" !a_flag;
    Printf.printf "B flag: %b\n" !b_flag