1 files changed, 20 insertions, 2 deletions
diff --git a/lib/Dirgraph.hs b/lib/Dirgraph.hs
index 0931ea0..b97a644 100644
--- a/lib/Dirgraph.hs
+++ b/lib/Dirgraph.hs
@@ -1,15 +1,21 @@
-{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE LambdaCase    #-}
+{-# LANGUAGE TupleSections #-}
 
 -- | Simple directed graphs, for dependency checking
 module Dirgraph where
 
 
 import           CheckMap        (MapResult (mapresultDepends))
-import           Data.Map.Strict (Map, mapMaybeWithKey, mapWithKey)
+import           Control.Monad   (forM_)
+import           Data.Functor    ((<&>))
+import           Data.Map.Strict (Map, mapMaybeWithKey, mapWithKey,
+                                  traverseWithKey)
 import qualified Data.Map.Strict as M
 import           Data.Set        (Set, (\\))
 import qualified Data.Set        as S
 import           Paths           (normalise)
+import           Text.Dot        (Dot, (.->.))
+import qualified Text.Dot        as D
 import           Types           (Dep (LocalMap))
 import           Witherable      (mapMaybe)
 
@@ -47,3 +53,15 @@ reachableFrom entrypoint graph = recursive mempty (S.singleton entrypoint)
 unreachableFrom :: Ord a => a -> Graph a -> Set a
 unreachableFrom entrypoint graph =
   nodes graph \\ reachableFrom entrypoint graph
+
+graphToDot :: Graph FilePath -> Dot ()
+graphToDot graph = do
+  nodes <- traverseWithKey
+    (\name edges -> D.node [("label",name)] <&> (,edges))
+    graph
+
+  forM_ nodes $ \(node, edges) ->
+    forM_ edges $ \key ->
+      case M.lookup key nodes of
+        Just (other,_) -> node .->. other
+        _              -> pure ()