@hackage writer-cps-mtl0.1.1.6

The WriterT and RWST monad transformers provided by writer-cps-transformers are written in continuation passing style and avoid the space-leak problem of the traditional Control.Monad.Trans.Writer.Strict and Control.Monad.Trans.Writer.Lazy. See also (http://hackage.haskell.org/package/writer-cps-transformers).