std.string phobos

[pc]

Is there a way to make the functions in std.string, such as replace, pure? Many 
pure functions are going to  want to use these. Also, could some of them be 
executable at compile time?

For me, using D2.032, this did not compile.

pure string replaceXX(string str){
  return replace(str,"XX","X"); 
}

If I am missing something, help!