This package [1] provides STM data structures with IO hooks. The basic building blocks are instances of class TBox. Such an instance is an STM variable that might contain a value of some type a. In contrast to a plain 'TVar (Maybe a)', a TBox has IO hooks that are executed transparently on writes and reads. The IO hooks of the AdvSTM monad extend the atomicity of STM transactions to the on-commit IO actions, which makes it particularly suitable for implementing a persistent and thread-safe storage. Currently the only instance of class TBox is type TFile. A TFile serializes its content to a file using Data.Binary. New in this release is the implementation of a skip list in module Control.Concurrent.TBox.TSkipList that provides thread-safe persistency. A skip list is a probabilistic data structure that provides expected run time of O(log n) for dictionary operations (insert, lookup, filter, leq, min, delete, update) similar to a balanced tree. The main advantage of a skip list is that it does not need rebalancing, which could lead to high contention among transactions. The TFile-skip list instance tries to reconstruct the content of its elements from the TFile-directory. See module Control.Concurrent.TFile.TSkipList for a usage example. Feedback is highly appreciated! [1] http://hackage.haskell.org/package/tbox