X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Data%2FTree.hs;h=f2a55f59d28e32ef5ea75804fdc609aa12b4c4ac;hb=a14a8400e73713d5ac8c1b3405ac13f4cfe86acf;hp=113bc4c1ceb5d05bb4b601c58c9c4f49e4961d88;hpb=fde33aa064e87cf823a501ac5c909e93d169fe37;p=haskell-directory.git

diff --git a/Data/Tree.hs b/Data/Tree.hs
index 113bc4c..f2a55f5 100644
--- a/Data/Tree.hs
+++ b/Data/Tree.hs
@@ -28,13 +28,18 @@ module Data.Tree(
 import Prelude
 #endif
 
+import Control.Applicative (Applicative(..), (<$>))
 import Control.Monad
+import Data.Monoid (Monoid(..))
 import Data.Sequence (Seq, empty, singleton, (<|), (|>), fromList,
 			ViewL(..), ViewR(..), viewl, viewr)
-import qualified Data.Sequence as Seq (foldl)
+import Data.Foldable (Foldable(foldMap), toList)
+import Data.Traversable (Traversable(traverse))
 import Data.Typeable
 
-#include "Typeable.h"
+#ifdef __GLASGOW_HASKELL__
+import Data.Generics.Basics (Data)
+#endif
 
 -- | Multi-way trees, also known as /rose trees/.
 data Tree a   = Node {
@@ -42,21 +47,30 @@ data Tree a   = Node {
 		subForest :: Forest a	-- ^ zero or more child trees
 	}
 #ifndef __HADDOCK__
+# ifdef __GLASGOW_HASKELL__
+  deriving (Eq, Read, Show, Data)
+# else
   deriving (Eq, Read, Show)
+# endif
 #else /* __HADDOCK__ (which can't figure these out by itself) */
 instance Eq a => Eq (Tree a)
 instance Read a => Read (Tree a)
 instance Show a => Show (Tree a)
+instance Data a => Data (Tree a)
 #endif
 type Forest a = [Tree a]
 
+#include "Typeable.h"
 INSTANCE_TYPEABLE1(Tree,treeTc,"Tree")
 
 instance Functor Tree where
-  fmap = mapTree
+  fmap f (Node x ts) = Node (f x) (map (fmap f) ts)
+
+instance Traversable Tree where
+  traverse f (Node x ts) = Node <$> f x <*> traverse (traverse f) ts
 
-mapTree              :: (a -> b) -> (Tree a -> Tree b)
-mapTree f (Node x ts) = Node (f x) (map (mapTree f) ts)
+instance Foldable Tree where
+  foldMap f (Node x ts) = f x `mappend` foldMap (foldMap f) ts
 
 -- | Neat 2-dimensional drawing of a tree.
 drawTree :: Tree String -> String
@@ -123,9 +137,7 @@ unfoldTreeM_BF f b = liftM getElement $ unfoldForestQ f (singleton b)
 -- /Breadth-First Numbering: Lessons from a Small Exercise in Algorithm Design/,
 -- by Chris Okasaki, /ICFP'00/.
 unfoldForestM_BF :: Monad m => (b -> m (a, [b])) -> [b] -> m (Forest a)
-unfoldForestM_BF f = liftM toRevList . unfoldForestQ f . fromList
-  where toRevList :: Seq c -> [c]
-	toRevList = Seq.foldl (flip (:)) []
+unfoldForestM_BF f = liftM toList . unfoldForestQ f . fromList
 
 -- takes a sequence (queue) of seeds
 -- produces a sequence (reversed queue) of trees of the same length