Implement zipper for attachment trees

src/Dodge/Data/DoubleTree.hs

@@ -41,31 +41,27 @@ data LabelDoubleTree b a = LDT {_ldtValue :: a, _ldtLeft :: [(b,LabelDoubleTree
     deriving (Eq,Ord,Show,Read)
 
 -- I am not sure about the double use of records here
-data ContextLDT b a = TopLDT 
-        { _cldtValue :: a}
+data ContextLDT b a = TopLDT
     | LeftwardLDT
         { _cldtUp :: ContextLDT b a  
-        , _cldtCloseLeft :: [LabelDoubleTree b a] 
+        , _cldtCloseLeft :: [(b,LabelDoubleTree b a)] 
+        , _cldtParent :: a
         , _cldtLink :: b
-        , _cldtValue :: a
-        , _cldtCloseRight :: [LabelDoubleTree b a]
-        , _cldtFarRight :: [LabelDoubleTree b a]
+        , _cldtCloseRight :: [(b,LabelDoubleTree b a)]
+        , _cldtFarRight :: [(b,LabelDoubleTree b a)]
         }
     | RightwardLDT 
         { _cldtUp :: ContextLDT b a  
-        , _cldtFarLeft :: [LabelDoubleTree b a]
-        , _cldtCloseLeft :: [LabelDoubleTree b a] 
+        , _cldtFarLeft :: [(b,LabelDoubleTree b a)]
+        , _cldtCloseLeft :: [(b,LabelDoubleTree b a)] 
+        , _cldtParent :: a
         , _cldtLink :: b
-        , _cldtValue :: a
-        , _cldtCloseRight :: [LabelDoubleTree b a]
+        , _cldtCloseRight :: [(b,LabelDoubleTree b a)]
         }
 
--- this is not quite right, it duplicates the value when the context is at the
--- top
 data LocationLDT b a = LocLDT
     { _locLdtContext :: ContextLDT b a
-    , _locLdtLeft :: [LabelDoubleTree b a]
-    , _locLdtRight :: [LabelDoubleTree b a]
+    , _locLDT :: LabelDoubleTree b a
     }
 
 instance Functor DoubleTree where
@@ -84,5 +80,7 @@ instance Bifunctor LabelDoubleTree where
 
 makeLenses ''DoubleTree
 makeLenses ''LabelDoubleTree
+makeLenses ''LocationLDT
+makeLenses ''ContextLDT
 deriveJSON defaultOptions ''DoubleTree
 deriveJSON defaultOptions ''LabelDoubleTree