abstract, parameterized interface to mutable Deques

 An abstract interface to highly-parameterizable queues/deques.
 .
 Background: There exists a feature space for queues that extends between:
   * simple, single-ended, non-concurrent, bounded queues
   * double-ended, threadsafe, growable queues
 with important points inbetween (such as the queues used for
 work-stealing).
 .
 This package includes an interface for Deques that allows the
 programmer to use a single API for all of the above, while using
 the type-system to select an efficient implementation given the
 requirements (using type families).
 .
 This package also includes a simple reference implementation based
 on IORef and Data.Sequence.
 .
 This package provides a library for the Haskell programming language.
 See http://www.haskell.org/ for more information on Haskell.