--- a/Jungle.hs	Tue Mar 26 16:24:20 2013 +0900
+++ b/Jungle.hs	Tue Mar 26 17:30:20 2013 +0900
@@ -19,10 +19,9 @@
 ) where
 
 import qualified Data.Map as Map
-import qualified Data.ByteString as B
 
 data Children   = Children (Map.Map Int Node) deriving (Show)
-data Attributes = Attributes (Map.Map String B.ByteString) deriving (Show)
+data Attributes = Attributes (Map.Map String String) deriving (Show)
 
 data Node = Empty
           | Node
@@ -63,8 +62,8 @@
 at :: Children -> Int -> Node
 at (Children map) pos = Map.findWithDefault Empty pos map
 
-get :: Attributes -> String -> B.ByteString
-get (Attributes map) key = Map.findWithDefault B.empty key map
+get :: Attributes -> String -> String
+get (Attributes map) key = Map.findWithDefault "" key map
 
 addNewChildAt :: Tree -> Path -> Int -> Node -> Tree
 addNewChildAt tree path pos node = Tree $ addNewChildAt' (getRootNode tree) path pos node
@@ -75,9 +74,6 @@
   where 
     child = at (getChildren parent)
 
--- RootNodeの子が消せない
--- addNewChildAtが下に付け加えることしかできないから
--- RootNodeのこの場合例外処理すればいけるけどスマートな書き方ないか考える
 deleteChildAt :: Tree -> Path -> Int -> Tree
 deleteChildAt tree path pos = editTree tree path (deleteChild target pos)
   where
@@ -98,7 +94,7 @@
 deleteChild Empty _ = Empty
 deleteChild (Node (Children map) attributes) pos = Node (Children (Map.delete pos map)) attributes
 
-putAttribute :: Tree -> Path -> String -> B.ByteString -> Tree
+putAttribute :: Tree -> Path -> String -> String -> Tree
 putAttribute tree path key value = editTree tree path (putAttribute' target key value)
   where
     root = getRootNode tree
@@ -110,7 +106,7 @@
     root = getRootNode tree
     target = getNode root path
 
-putAttribute' :: Node -> String -> B.ByteString -> Node
+putAttribute' :: Node -> String -> String -> Node
 putAttribute' Empty key value = putAttribute' (Node (Children Map.empty) (Attributes Map.empty)) key value
 putAttribute' (Node children (Attributes map)) key value = Node children (Attributes (Map.insert key value map))