Albert Lai:
Thanks. I got the poit more or less; Each invocation creates a new
IORef instance. UnsafePerformIO appears to generate a unique IORef
that can be shared (sorry for my imperative vocabulary, I´m sill
contaminated by al these evil languages ;).
I tried with "usafePerformIO NewTVar v" but the program fails
miserably in a memory fault. I finally did it well usign a IORef than
contains the TVar:
refcache =unsafePerformIO $ (do c <- atomically $ newTVar emptyFM
newIORef c)
and then dereferencing refcache in the IO Monad I get ever the same
context no matter where i do it:
do
tvcache <- readIORef refcache
atomically $ do
finiteMap <- readTVar tvcache
(useful code here at last)...
---------------------
Who said that Haskell is difficult?. Jokes apart, STM is powerful. I
will share the transactional cache when I have it tested.
-----------referred message:-------
Message: 1
Date: 12 May 2006 00:19:28 -0400
From: Albert Lai
stmcache= newTVar 0
I will explain what this doesn't with an analogy. import Data.IORef notglobal = newIORef True main = do a <- notglobal b <- notglobal writeIORef a False x <- readIORef b print x To better show what's going on, I also provide this for contrast: import Data.IORef import System.IO.Unsafe global = unsafePerformIO (newIORef True) main = do x <- readIORef global print x writeIORef global False x <- readIORef global print x