gistfile1.txt

{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE Strict #-}
{-# LANGUAGE StrictData #-}
import Debug.Trace
import System.IO
import System.IO.Unsafe

main  :: IO ()
main = do
  hSetBuffering stderr NoBuffering
  hSetBuffering stdout NoBuffering
  let !b = (fff 2 10)
  putStrLn $ "b: " ++ show b
  let !c = (fff 3 15)
  putStrLn $ "c: " ++ show c
  print "---"

fff :: Int -> Int -> Int
fff = do
  (-) . ff

hmm :: a -> a
hmm x = unsafePerformIO $! do
  print "this only happens once"
  pure x

ff :: Int -> Int
ff z = do
  hmm (trace "x is: " . traceShowId) $ z