anchor.diff:  (* ------------------------------------------------------------------------- *)
   (* Character discrimination.                                                 *)
   (* ------------------------------------------------------------------------- *)
  -
  -/// Returns the ASCII code for the first (0th) character in a string.
  -let inline private charcode (s : string) =
  -//    #if DEBUG
  -//    if String.length s <> 1 then
  -//        logger.Debug ("NHol.printer.charcode: The string should contain exactly one (1) character, but it contains {0} characters. (s = {1})",
  -//            String.length s, s)
  -//    #endif
  -    // Note: In F# 65536 retuns 0, so the max is 65535 in F#.
  -    int s.[0]
   
   //
   let private ctable =
  
positive.code:         |> max (maxAsciiCode symbs)
          |> max (maxAsciiCode alphas)
          |> max (maxAsciiCode nums)
          |> max 256
          |> Array.zeroCreate
  
      String.iter (fun c -> Array.set ctable (int c) 1) spaces
  
negative.code:     
      let ctable =
          let inline maxAsciiCode str =
              // OPTIMIZE : Use String.mapReduce from a future version of ExtCore, instead of String.fold.
              String.fold (fun x c -> max x (int c)) 0 str
  
          maxAsciiCode spaces
  