(* arg.sml *) open BasicIO Fnlib; exception Bad of string datatype spec =    String  of (string -> unit)  | Int     of (int -> unit)  | Unit    of (unit -> unit)  | Real    of (real -> unit); datatype error =    Unknown of string  | Wrong of string * string * string  (* option, actual, expected *)  | Missing of string  | Message of string; fun stop error =  let val progname = if Vector.length Miscsys.command_line > 0                     then Vector.sub(Miscsys.command_line, 0)                     else "(?)"      val message =        case error of            Unknown s =>              progname ^ ": unknown option: \"" ^ s ^ "\"."          | Missing s              => progname ^ ": option \"" ^ s ^ "\" needs an argument."          | Wrong (opt, arg, expected)              => progname ^ ": wrong argument \"" ^ arg ^ "\"; option \""                   ^ opt ^ "\" expects " ^ expected ^ "."          | Message s              => progname ^ ": " ^ s  in     output(std_err, message); output(std_err, "\n"); flush_out std_err;     exit 2  end; prim_val sml_int_of_string : string -> int = 1 "sml_int_of_string";prim_val sml_float_of_string : string -> real = 1 "sml_float_of_string"; fun listOfVector v =  List.tabulate(Vector.length v, fn i => Vector.sub(v, i)); fun parse speclist anonfun =  let fun p [] = ()        | p (s::t) =            if size s >= 1 andalso CharVector.sub(s, 0) = #"-"            then do_key s t            else ((anonfun s; p t)                   handle Bad m => stop (Message m))      and do_key s l =        let val action =              lookup s speclist                handle Subscript => stop (Unknown s)        in          (case (action, l) of               (Unit f, l) => (f (); p l)             | (String f, arg::t) => (f arg; p t)             | (Int f, arg::t) =>                 let val arg_i =                       sml_int_of_string arg                       handle Fail _ =>                         stop (Wrong (s, arg, "an integer"))                 in f arg_i; p t end             | (Real f, arg::t) =>                 let val arg_r =                       sml_float_of_string arg                       handle Fail _ =>                         stop (Wrong (s, arg, "a real"))                 in f arg_r; p t end             | (_, []) => stop (Missing s)          ) handle Bad m => stop (Message m)        end  in    case listOfVector Miscsys.command_line of        [] => ()      | a::l => p l  end;