updatable one-shot timer polled with STM; profiling libraries

 This library lets you create a one-shot timer, poll it using STM,
 and update it to ring at a different time than initially
 specified.
 .
 It uses GHC event manager timeouts when available, yielding
 performance similar to threadDelay and registerDelay. Otherwise,
 it falls back to forked threads and threadDelay.
 .
 This package provides a library for the Haskell programming language, compiled
 for profiling. See http://www.haskell.org/ for more information on Haskell.