(* getopt-sig.sml * * COPYRIGHT (c) 1998 Bell Labs, Lucent Technologies. *  * A SML port of GNU's getopt library. * * This port is derived from Sven Panne's  * <Sven.Panne@informatik.uni-muenchen.de> * implementation of the getopt library in Haskell <http://www.haskell.org> *  * The following comments are lifted from Sven's code: * *   Two rather obscure features are missing: The Bash 2.0 non-option hack (if *   you don't already know it, you probably don't want to hear about it...)  *   and the recognition of long options with a single dash (e.g. '-help' is *   recognised as '--help', as long as there is no short option 'h'). *  *   Other differences between GNU's getopt and this implementation: *     * To enforce a coherent description of options and arguments, there are *       explanation fields in the option/argument descriptor. *     * Error messages are now more informative, but no longer POSIX *       compliant... :-( *  *  *  * A difference with Sven's port: errors now invoke an error callback, rather * than returning error strings while continuing processing options. * The full generality of the latter does not seem justified. *)signature GET_OPT =   sig      datatype 'a arg_order        = RequireOrder        | Permute        | ReturnInOrder of string -> 'a      (* What to do with options following non-options:       * RequireOrder: no option processing after first non-option       * Permute: freely intersperse options and non-options       * ReturnInOrder: wrap non-options into options       *)                datatype 'a arg_descr        = NoArg of unit -> 'a        | ReqArg of (string -> 'a) * string        | OptArg of (string option -> 'a) * string      (* Description of an argument option:       * NoArg: no argument required       * ReqArg: option requires an argument       * OptArg: optional argument       *)                type 'a opt_descr = {          short : string,          long : string list,          desc : 'a arg_descr,          help : string        }      (* Description of a single option *)      val usageInfo : {	      header : string,	      options : 'a opt_descr list	    } -> string      (* takes a header string and a list of option descriptions and       * returns a string explaining the usage information       *)       val getOpt : {	      argOrder : 'a arg_order,	      options : 'a opt_descr list,	      errFn : string -> unit	    } -> string list -> ('a list * string list)      (* takes as argument an arg_order to specify the non-options       * handling, a list of option descriptions, an error callback,       * and a command line containing the options and arguments,       * and returns a list of (options, non-options)       *)         end