scalaz/scalaz — pull request #835 by justjoheinz (2014-10-29 13:41:05+00:00)
Title: Provide runZero, eval, evalZero, exec & execZero for ReaderWriterStateT ...

...in analogy to StateT

Please review carefully, I found this methods to be useful, however I am not sure if there is not another way to achieve the same result. They all exist in StateT and have been adopted to preserve the writer part.