lib: note a problem with dbg*IO

This commit is contained in:
Simon Michael 2016-12-07 07:52:10 -08:00
parent 2e8e67aa09
commit 00e2a8a327

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@ -117,6 +117,9 @@ dbg9 = tracePrettyAt 9
-- | Convenience aliases for tracePrettyAtIO.
-- Like dbg, but convenient to insert in an IO monad.
-- XXX These have a bug; they should use traceIO, not trace,
-- otherwise GHC can occasionally over-optimise
-- (cf lpaste a few days ago where it killed/blocked a child thread).
dbg0IO :: (MonadIO m, Show a) => String -> a -> m ()
dbg0IO = tracePrettyAtIO 0