regading detection of stdin

[Hugo Florentino]

Hi,

I was trying to do something like this (using dmd.2.064.2 both from 
Windows and Linux), but if nothing is passed from stdin and no parameter 
is provided, the application freezes:

import std.stdio, std.file: readText;

int main(string[] args) {
  string s;
  switch (args.length) {
    case 1:
      if ((s = stdin.readln()) is null)
        writeln("No argument passed as parameter or from stdin.");
      else
        writeln("Argument passed from stdin succesfully stored in 
variable s.");
      scope (failure) {
        writeln("Error reading from stdin.");
        return -1;
      }
      break;
    case 2:
      s = readText(args[1]);
      scope (failure) {
        writeln("Error reading from file passed as parameter.");
        return -2;
      }
      writeln("Argument passed as parameter succesfully stored in 
variable s.");
      break;
    default:
      writeln("Incorrect number of parameters. Maximum is one.");
      return -3;
  }
  return 0;
}


Where is the problem?

Regards, Hugo