Allow for indentation of individual selection items

src/Dodge/Data/DoubleTree.hs

@@ -10,6 +10,12 @@ import Data.Aeson
 import Data.Aeson.TH
 import Data.Bifunctor
 
+data DoubleTreeNodeType
+    = DTRootNode
+    | DTTopNode
+    | DTMidAboveNode
+    | DTMidBelowNode
+    | DTBottomNode
 
 data DoubleTree a = DT {_dtValue :: a,_dtLeft :: [DoubleTree a],_dtRight :: [DoubleTree a]}
     deriving (Eq,Ord,Show,Read)
@@ -21,6 +27,9 @@ data LabelDoubleTree b a = LDT {_ldtValue :: a, _ldtLeft :: [(b,LabelDoubleTree
 instance Functor DoubleTree where
     fmap f (DT x l r) = DT (f x) (fmap (fmap f) l) (fmap (fmap f) r)
 
+instance Foldable DoubleTree where
+    foldMap f (DT x l r) = foldMap (foldMap f) l <> f x <> foldMap (foldMap f) r
+
 instance Functor (LabelDoubleTree b) where
     fmap f (LDT x l r) = LDT (f x) (fmap (second $ fmap f) l) (fmap (second $ fmap f) r)