diff --git a/src/Data/Graphviz.hs b/src/Data/Graphviz.hs
index 06e60e4..49a5297 100644
--- a/src/Data/Graphviz.hs
+++ b/src/Data/Graphviz.hs
@@ -11,4 +11,6 @@ digraph es = Text.unlines
   ]
 
 edges :: [NonEmpty Text] -> Text
-edges = Text.unlines . fmap ((\(x :| xs) -> Text.unlines $ (\y -> x <> " -> " <> y <> ";") <$> xs))
+edges = Text.unlines . fmap f
+  where
+  f (x :| xs) = Text.unlines $ (\y -> x <> " -> " <> y <> ";") <$> xs
diff --git a/src/Data/Language/Ruby/AST.hs b/src/Data/Language/Ruby/AST.hs
index 3ef7beb..cf896c2 100644
--- a/src/Data/Language/Ruby/AST.hs
+++ b/src/Data/Language/Ruby/AST.hs
@@ -147,7 +147,7 @@ instance FromJSON Casgn where
     _ -> empty
 
 
-data Array = Array
+newtype Array = Array
   { statements :: [Statement]
   }
 deriving stock instance Show Array
@@ -443,7 +443,7 @@ instance FromJSON Lvasgn where
     [Aeson.String "lvasgn", atom, statement] -> Lvasgn <$> parseJSON atom <*> parseJSON statement
     _ -> empty
 
-data Lvar = Lvar
+newtype Lvar = Lvar
   { atom      :: Atom
   }
 
@@ -458,7 +458,7 @@ instance FromJSON Lvar where
     [Aeson.String "lvar", atom] -> Lvar <$> parseJSON atom
     _ -> empty
 
-data Ivar = Ivar
+newtype Ivar = Ivar
   { atom      :: Atom
   }