David Roundy
{-# NOINLINE _progressData #-} _progressData :: IORef (Map String ProgressData) _progressData = unsafePerformIO $ newIORef empty
updateProgressData :: String -> (ProgressData -> ProgressData) -> IO () updateProgressData k f = when (progressMode) $ modifyIORef _progressData (adjust f k)
The question I'm asking myself is why you would want to modify a reference to an always empty Map, which would be the case if unsafePerformIO performs its action every time. If it doesnt' (and experience suggest that it doesn't, as does the faithful usage of {-# NOINLINE #-}, BUT YOU'LL NEVER, EVER, KNOW), I'm wondering why you don't create the IORef in beginTedious and pass it around. Possibly even with an implicit parameter. And, yes, without multiple writing threads locking is unnecessary, and mostly even with multiple writing threads, if they don't read, too. /me mandates the renaming of unsafePerformIO to iReallyReallyThoughtReallyHardAboutThisAndThereReallyIsNoDifferentWayThanToUseThisDreadedUnsafePerformIO. OTOH, I have no idea what causes the segfault. -- (c) this sig last receiving data processing entity. Inspect headers for past copyright information. All rights reserved. Unauthorised copying, hiring, renting, public performance and/or broadcasting of this signature prohibited.