-- Skip a bunch of output in Core that distracts from the main point
{-# OPTIONS -dsuppress-all -dno-suppress-type-signatures #-}

-- If this line is here, common subexpression elimination (CSE) is turned off.
-- Comment this line to enable CSE, and see GHC deduplicating the "computation"
-- for x.
{-# OPTIONS -fno-cse #-}

x :: Num a => a
x = 4

main = do
  print x
  print x
  putStrLn "hi"
  print x