title: Big datastructures in functional programming
body: <p>I'm newbie in Functional Programming. </p>
  
  <p>I have a huge neural network with thousands of neurons and every connection between neurons has its weight. I have to update these weights very often, several thousand times per learning session. </p>
  
  <p>Is FP still applicable here? I mean in fp we can't modify variables and only able to return new variables not changing previous values. Does this mean I have to recreate whole network on every weight update?</p>