-----------------------------------------------------------------------------
-- |
-- Module : Data.HasKey
-- Copyright : Peter Robinson 2009
-- License : LGPL
--
-- Maintainer : Peter Robinson <thaldyron@gmail.com>
-- Stability : experimental
-- Portability : non-portable (requires STM)
--
-----------------------------------------------------------------------------
module Data.HasKey( HasKey(key) )
where
-- | Types where values have a key for indexing.
class HasKey a k | a -> k where
key :: a -> k