gistfile1.txt

withFunction :: (Int -> IO b) -> IO b
withFunction fun = do
  let val = 3
  fun val
  
  
class WithFunction proxy where
  withFunction_ :: proxy -> (Int -> IO b) -> IO b

data Number1 = Number1

instance WithFunction Number1 where
  withFunction_ _ = withFunction


main :: IO ()
main = do
  testFunction Number1
  
testFunction :: WithFunction proxy => proxy -> IO ()
testFunction p = do
  val1 <- withFunction_ p $ \val -> do putStrLn "lambda1"; return "hello"
  putStrLn $ "val1 = " ++ (show val1)
  val2 <- withFunction_ p $ \val -> do putStrLn "lambda2"; return $ val + 5
  putStrLn $ "val2 = " ++ (show val2)