I assume you're trying this at the GHCi prompt, which is where you're problem is coming from, specifically on the first line. When you do: > let aaa = unsafePerformIO $ newIORef [] GHCi takes a wild stab at the type of [] and comes up with the type [()], so now you have a IORef [()] type, which is why when you try to store [1,2,3] in the IORef you get back [(),(),()]. Try this instead and it should work: > let aaa = unsafePerformIO $ newIORef ([] :: [Int])
-R. Kyle Murphy -- Curiosity was framed, Ignorance killed the cat. On Thu, Oct 22, 2009 at 01:02, zaxis <z_a...@163.com> wrote: > > > let aaa = unsafePerformIO $ newIORef [] > > writeIORef aaa [1,2,3] > > readIORef aaa > [(),(),()] > > sincerely! > -- > View this message in context: > http://www.nabble.com/why-cannot-i-get-the-value-of-a-IORef-variable---tp26004111p26004111.html > Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe >
_______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
