Fix incorrect changes to C types in a foreign import for nhc98.

[haskell-directory.git] / Data / Tree.hs

diff --git a/Data/Tree.hs b/Data/Tree.hs
index bc103b8..c159a74 100644 (file)
--- a/Data/Tree.hs
+++ b/Data/Tree.hs
@@ -28,7 +28,7 @@ module Data.Tree(
 import Prelude
 #endif
 
-import Control.Applicative (Applicative(..))
+import Control.Applicative (Applicative(..), (<$>))
 import Control.Monad
 import Data.Monoid (Monoid(..))
 import Data.Sequence (Seq, empty, singleton, (<|), (|>), fromList,
@@ -66,6 +66,16 @@ INSTANCE_TYPEABLE1(Tree,treeTc,"Tree")
 instance Functor Tree where
   fmap f (Node x ts) = Node (f x) (map (fmap f) ts)
 
+instance Applicative Tree where
+  pure x = Node x []
+  Node f tfs <*> tx@(Node x txs) =
+    Node (f x) (map (f <$>) txs ++ map (<*> tx) tfs)
+
+instance Monad Tree where
+  return x = Node x []
+  Node x ts >>= f = Node x' (ts' ++ map (>>= f) ts)
+    where Node x' ts' = f x
+
 instance Traversable Tree where
   traverse f (Node x ts) = Node <$> f x <*> traverse (traverse f) ts
 
@@ -93,7 +103,7 @@ draw (Node x ts0) = x : drawSubTrees ts0
 -- | The elements of a tree in pre-order.
 flatten :: Tree a -> [a]
 flatten t = squish t []
-  where squish (Node x ts) xs = x:foldr squish xs ts
+  where squish (Node x ts) xs = x:Prelude.foldr squish xs ts
 
 -- | Lists of nodes at each level of the tree.
 levels :: Tree a -> [[a]]
@@ -120,7 +130,7 @@ unfoldTreeM f b = do
 #ifndef __NHC__
 unfoldForestM :: Monad m => (b -> m (a, [b])) -> [b] -> m (Forest a)
 #endif
-unfoldForestM f = mapM (unfoldTreeM f)
+unfoldForestM f = Prelude.mapM (unfoldTreeM f)
 
 -- | Monadic tree builder, in breadth-first order,
 -- using an algorithm adapted from
@@ -146,7 +156,7 @@ unfoldForestQ f aQ = case viewl aQ of
        EmptyL -> return empty
        a :< aQ -> do
                (b, as) <- f a
-               tQ <- unfoldForestQ f (foldl (|>) aQ as)
+               tQ <- unfoldForestQ f (Prelude.foldl (|>) aQ as)
                let (tQ', ts) = splitOnto [] as tQ
                return (Node b ts <| tQ')
   where splitOnto :: [a'] -> [b'] -> Seq a' -> (Seq a', [a'])