thank you! In fact i really donot understand "unsafePerformIO" very much !
Thomas DuBuisson wrote: > > zaxis <z_a...@163.com> wrote: >>> let aaa = unsafePerformIO $ newIORef [] >>> writeIORef aaa [1,2,3] >>> readIORef aaa >> [(),(),()] > > What in Haskells name do you think you're doing? Don't use > unsafePerformIO like that! Its unnecessary and a bit concerning, > really. > > Prelude> :m Data.IORef > Prelude Data.IORef> x <- newIORef [] :: IO (IORef [Int]) > Prelude Data.IORef> writeIORef x [1,2,3] > Prelude Data.IORef> readIORef x > [1,2,3] > > >> >> 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 > > -- View this message in context: http://www.nabble.com/why-cannot-i-get-the-value-of-a-IORef-variable---tp26004111p26004340.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