title: Immutable functional objects in highly mutable domain
body: <p>I'm currently learning functional programming in my spare time with Scala, and I have an idle newbie question.</p>
  
  <p>I can see the elegance of having immutable objects when doing something like calculating a Haar wavelet transform - i.e. when the data itself being represented by the objects doesn't change.</p>
  
  <p>But I saw a blog where someone had a small game as an example when demonstrating immutability. If a creature object recieved damage, it didn't change its state - it returned a new creature object with the new hitpoints and a new "aggro towards X" flag. But if we were to design something like a MMORPG, World of Warcraft say. A hundred players in a battleground... possibly thousands of attacks and buffing/debuffing spell effects affecting them in different ways. Is it still possible to design the system with completely immutable objects? To me it would seem like there would be a ginormous swarm of new instances each 'tick'. And to get the currently valid instance of objects, all clients would constantly have to go through some sort of central "gameworld" object, or?</p>
  
  <p>Does functional programming scale for this, or is this a case of "best tool for best job, probably not immutable here"?</p>