graphviz package generates graph with wrong arc direction.

graphviz-direction.hs

#!/usr/bin/env stack
-- stack --resolver nightly-2017-10-08 runghc --package graphviz
import qualified Data.GraphViz.Types.Graph as GV
import Data.GraphViz.Commands (GraphvizOutput(..), dirCommand, runGraphvizCommand)

main :: IO ()
main = do
  -- This generates an arc with the wrong direction. There should be an arc from 0 to 1 but this code produces
  -- an arc from 1 to 0, contrary to the documentation of the fields of DotEdge, popular convention and fgl
  -- convention.
  let gv = GV.mkGraph [GV.DotNode (0 :: Int) [], GV.DotNode 1 []] [GV.DotEdge 0 1 []]
  runGraphvizCommand dirCommand gv DotOutput "/tmp/gv.dot"
  pure ()

{-
Output:
digraph {
        graph [bb="0,0,54,108"];
        node [label="\N"];
        0        [height=0.5,
                pos="27,18",
                width=0.75];
        1        [height=0.5,
                pos="27,90",
                width=0.75];
        1 -> 0   [pos="e,27,36.104 27,71.697 27,63.983 27,54.712 27,46.112"];
}
-}