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src/Dodge/Data/MetaTree.hs

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+{-# LANGUAGE StrictData #-}
+{-# LANGUAGE TemplateHaskell #-}
+
+module Dodge.Data.MetaTree where
+
+import Control.Lens
+import Data.Tree
+
+data MetaTree a b = MTree
+    {_mtLabel :: b, _mtTree :: MetaNode a b, _mtBranches :: [MetaBranch a b]}
+
+data MetaNode a b
+    = NodeTree {_nodeTree :: Tree a}
+    | NodeMTree {_nodeMetaTree :: MetaTree a b}
+
+data MetaBranch a b = MBranch {_mbAttach :: a -> Maybe a, _mbTree :: MetaTree a b}
+
+newtype SelfTree a = ST {_unST :: Tree (a, Either (Tree a) (SelfTree a))}
+
+makeLenses ''MetaTree
+makeLenses ''MetaBranch
+makeLenses ''MetaNode
+
+instance Functor (MetaTree a) where
+    fmap f (MTree b mn bs) = MTree (f b) (mn & nodeMetaTree %~ fmap f) (map (mbTree %~ fmap f) bs)