title: How do I get the sums of the digits of a large number in Haskell?
body: <p>I'm a C++ Programmer trying to teach myself Haskell and it's proving to be challenging grasping the basics of using functions as a type of loop. I have a large number, 50!, and I need to add the sum of its digits. It's a relatively easy loop in C++ but I want to learn how to do it in Haskell. </p>
  
  <p>I've read some introductory guides and am able to get 50! with</p>
  
  <p>sum50fac.hs::</p>
  
  <pre><code>fac 0 = 1
  fac n = n * fac (n-1)
  x = fac 50
  main = print x
  </code></pre>
  
  <p>Unfortunately at this point I'm not entirely sure how to approach the problem.
  Is it possible to write a function that adds (mod) x 10 to a value and then calls the same function again on x / 10 until x / 10 is less than 10?  If that's not possible how should I approach this problem?</p>
  
  <p>Thanks! </p>