Add ($!!) and force to deepseq
For the related discussion on libraries@, please see http://www.haskell.org/pipermail/libraries/2011-July/016540.html
The result of the discussion was that $!! should be added to deepseq:
($!!) :: (NFData a) => (a -> b) ->a -> b f $!! x = x `deepseq` f x infixr 0 $!!
Also, that force should be added but with suitable documentation to indicate possible ways in which it may behave other than as you'd expect:
force :: (NFData a) => a -> a force x = x `deepseq` x