Example of an unused IO operation in a "do" block executed regardless of the fact that it's unused

lazyfileplay.hs

import System.IO

main = do
  inText <- getContents
  let inWords = words inText
  result <- f ( read (inWords !! 0) :: Int)
  putStrLn result

f :: Int -> IO String
f x = do
  h <- openFile "lazyfileplay-out.txt" WriteMode -- This seems to cause the file to be touched regardless of the fact
                                                 -- that it's not actually used. Is it because the "do" block just
                                                 -- executes everything regardless, as opposed to lazily-binding things
                                                 -- and only executing them when needed?
  return $ if x == 1 then "1" else "not 1"