Use GraphViz and diagrams together, with each doing what it does best:
GraphViz for laying out graphs, and diagrams for drawing them.

Makes use of the excellent
[graphviz package](http://hackage.haskell.org/package/graphviz) for
doing the actual communication with graphviz.  So this package is
actually little more than some glue code that makes it a bit easier to
interface `diagrams` and the `graphviz` package.