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