On 28 September 2010 15:35, Tom Hawkins
Has anyone in the STM community considered the ability to read a TVar, such that it would allow the transaction to complete even if the TVar was modified by another transaction?
Maybe something like this: (Pasted from http://www.haskell.org/ghc/docs/6.12.2/html/libraries/base-4.2.0.1/GHC-Conc.... ) readTVarIO :: TVar a -> IO a Return the current value stored in a TVar. This is equivalent to readTVarIO = atomically . readTVar but works much faster, because it doesn't perform a complete transaction, it just reads the current value of the TVar. Peter
(I am assuming this is not how STM works by default.) For example:
looselyReadTVar :: TVar a -> STM a
Atom [1] has similar semantics to STM. If Atom were to relax it's rule atomicity in this fashion, it could open the door to improved task scheduling and higher levels of program description. Has STM research already gone down this path?
-Tom
[1] http://hackage.haskell.org/package/atom _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe