Haskell IO: convert IO String to “Other type”

Question

I have a Haskell program which takes a file as an input and convert it into a binary search tree.

import System.IO    

data Tree a = EmptyBST | Node a (Tree a)          


        

Answer 1

You can't really escape the IO monad (except through unsafe functions) but there's no actual need to do that in your case:

main = do f <- fileRead
          let newtree = ins 5 f
          putStr $ show newtree

(live demo: here)