(* System interface *)

external get_argv: unit -> string array = "sys_get_argv"

let argv = get_argv()

external file_exists: string -> bool = "sys_file_exists"
external remove: string -> unit = "sys_remove"
external getenv: string -> string = "sys_getenv"
external command: string -> int = "sys_system_command"
external chdir: string -> unit = "sys_chdir"

type signal_behavior =
    Signal_default
  | Signal_ignore
  | Signal_handle of (int -> unit)

external signal: int -> signal_behavior -> unit = "install_signal_handler"

let sigabrt = -1
let sigalrm = -2
let sigfpe = -3
let sighup = -4
let sigill = -5
let sigint = -6
let sigkill = -7
let sigpipe = -8
let sigquit = -9
let sigsegv = -10
let sigterm = -11
let sigusr1 = -12
let sigusr2 = -13
let sigchld = -14
let sigcont = -15
let sigstop = -16
let sigtstp = -17
let sigttin = -18
let sigttou = -19

exception Break

let catch_break on =
  if on then
    signal sigint (Signal_handle(fun _ -> raise Break))
  else
    signal sigint Signal_default