Hi, I don't think we included this in the version we checked in. It should be fairly easy to add to the current implementation: it will mirror ReadTVar except that the old value is always selected. I'm afraid I can't remember exactly why we didn't include it. One reason might have been that it would constrain alternative implementations -- for example one built over hardware transactional memory which might not necessarily provide access to the old state. Tim -----Original Message----- From: haskell-cafe-bounces@haskell.org [mailto:haskell-cafe-bounces@haskell.org] On Behalf Of Thomas DuBuisson Sent: 19 January 2008 00:14 To: haskell-cafe@haskell.org Subject: [Haskell-cafe] Control.Concurrent.STM.old? Does the 'old' function referenced in the SPJ and Tim Harris data invariants paper stil exist? It is of type STM a -> STM a and allowed invariants to compare old TVar values with new ones. I can't find it in any of the Haddocks or the code (and the 'check' funciton is not commented in the Haddock). Tom _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe