title: Haskell IO String -> List
body: <p>Hey guys, I need some help, how can I sum a list from a file using the sum builtin function?</p>
  
  <p>example:
  text.txt contains [1,2,3,4]</p>
  
  <p>and i want to get this list from the file and sum these numbers with the sum builtin. Is it possible?</p>
  
  <p>Thanks!</p>