This package provides combinators for sequencing IO actions onto a thread pool. The thread pool is guaranteed to contain no more unblocked threads than a user-specified upper limit, thus minimizing contention. Furthermore, the parallel combinators can be used reentrantly - your parallel actions can spawn more parallel actions - without violating this property of the thread pool. The package is inspired by the thread <http://thread.gmane.org/gmane.comp.lang.haskell.cafe/56499/focus=56521>. Thanks to Neil Mitchell and Bulat Ziganshin for some of the code this package is based on.