cleaned things up, added basic haddocks

I took a light touch. If this is a serious library, consider looking into [Repa](https://hackage.haskell.org/package/repa) and the like.

![screenshot from 2014-12-13 20 47 23](https://cloud.githubusercontent.com/assets/320177/5426216/4be9e14e-8309-11e4-9102-a6574845efa0.png)