Hi all, I'm running this program: {-# LANGUAGE DeriveDataTypeable, ScopedTypeVariables #-} import GHC.Stack import Control.Exception.Base import Data.Typeable data MyException = MyException deriving (Show, Typeable) instance Exception MyException err1 :: IO Integer err1 = {-# SCC error1 #-} err2 >>= return err2 :: IO Integer err2 = {-# SCC error2 #-} throw MyException main = print =<< whoCreated =<< catch err1 =<< (\(_ :: MyException) -> return (42 :: Integer)) I'd expect `whoCreated` to return something like [Main.CAF, Main.main, Main.main.\] but instead this is the output: ["Main.CAF (<entire-module>)","Main.err2 (ioerr.hs:14:1-43)","Main.error2 (ioerr.hs:14:27-43)","Main.main (ioerr.hs:16:1-103)","Main.main.\\ (ioerr.hs:16:81-102)"] This output has two things that look somewhat weird to me. First, I'd expect cost-centre stack to be restored when exception is catched and then program would produce shorter stack trace like I mentioned above.(without err1 or err2 calls) Second, when no cost-centre restoring is done, I'd expect stack trace to include `Main.err1` and `Main.error1`. So can anyone explain my why stack trace contains err2 calls but not err1 calls? I think none of error1 and error2 should have been included in the stack trace or both of them should have been included. Thanks. --- Ömer Sinan Ağacan http://osa1.net