X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Data%2FData.hs;h=d9cab7a5e9365d6194d03fa1e59b06af68d3d00d;hb=HEAD;hp=646249eccd2a65dde85f5967989889b00af265a0;hpb=8afc9fecd586d3c4f7ef9c69fb1686a79e5f441d;p=ghc-base.git

diff --git a/Data/Data.hs b/Data/Data.hs
index 646249e..d9cab7a 100644
--- a/Data/Data.hs
+++ b/Data/Data.hs
@@ -1,3 +1,5 @@
+{-# LANGUAGE CPP, Rank2Types, ScopedTypeVariables #-}
+
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Data
@@ -310,20 +312,24 @@ class Typeable a => Data a where
   --
   gmapT f x0 = unID (gfoldl k ID x0)
     where
+      k :: Data d => ID (d->b) -> d -> ID b
       k (ID c) x = ID (c (f x))
 
 
   -- | A generic query with a left-associative binary operator
-  gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> a -> r
+  gmapQl :: forall r r'. (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> a -> r
   gmapQl o r f = unCONST . gfoldl k z
     where
+      k :: Data d => CONST r (d->b) -> d -> CONST r b
       k c x = CONST $ (unCONST c) `o` f x
+      z :: g -> CONST r g
       z _   = CONST r
 
   -- | A generic query with a right-associative binary operator
-  gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> a -> r
+  gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> a -> r
   gmapQr o r0 f x0 = unQr (gfoldl k (const (Qr id)) x0) r0
     where
+      k :: Data d => Qr r (d->b) -> d -> Qr r b
       k (Qr c) x = Qr (\r -> c (f x `o` r))
 
 
@@ -335,10 +341,12 @@ class Typeable a => Data a where
 
 
   -- | A generic query that processes one child by index (zero-based)
-  gmapQi :: Int -> (forall d. Data d => d -> u) -> a -> u
+  gmapQi :: forall u. Int -> (forall d. Data d => d -> u) -> a -> u
   gmapQi i f x = case gfoldl k z x of { Qi _ q -> fromJust q }
     where
+      k :: Data d => Qi u (d -> b) -> d -> Qi u b
       k (Qi i' q) a = Qi (i'+1) (if i==i' then Just (f a) else q)
+      z :: g -> Qi q g
       z _           = Qi 0 Nothing
 
 
@@ -347,7 +355,7 @@ class Typeable a => Data a where
   -- The default definition instantiates the type constructor @c@ in
   -- the type of 'gfoldl' to the monad datatype constructor, defining
   -- injection and projection using 'return' and '>>='.
-  gmapM   :: Monad m => (forall d. Data d => d -> m d) -> a -> m a
+  gmapM :: forall m. Monad m => (forall d. Data d => d -> m d) -> a -> m a
 
   -- Use immediately the monad datatype constructor 
   -- to instantiate the type constructor c in the type of gfoldl,
@@ -355,13 +363,14 @@ class Typeable a => Data a where
   --  
   gmapM f = gfoldl k return
     where
+      k :: Data d => m (d -> b) -> d -> m b
       k c x = do c' <- c
                  x' <- f x
                  return (c' x')
 
 
   -- | Transformation of at least one immediate subterm does not fail
-  gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> a -> m a
+  gmapMp :: forall m. MonadPlus m => (forall d. Data d => d -> m d) -> a -> m a
 
 {-
 
@@ -374,7 +383,9 @@ this end, we couple the monadic computation with a Boolean.
   gmapMp f x = unMp (gfoldl k z x) >>= \(x',b) ->
                 if b then return x' else mzero
     where
+      z :: g -> Mp m g
       z g = Mp (return (g,False))
+      k :: Data d => Mp m (d -> b) -> d -> Mp m b
       k (Mp c) y
         = Mp ( c >>= \(h, b) ->
                  (f y >>= \y' -> return (h y', True))
@@ -382,7 +393,7 @@ this end, we couple the monadic computation with a Boolean.
              )
 
   -- | Transformation of one immediate subterm with success
-  gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> a -> m a
+  gmapMo :: forall m. MonadPlus m => (forall d. Data d => d -> m d) -> a -> m a
 
 {-
 
@@ -397,7 +408,9 @@ was transformed successfully.
   gmapMo f x = unMp (gfoldl k z x) >>= \(x',b) ->
                 if b then return x' else mzero
     where
+      z :: g -> Mp m g
       z g = Mp (return (g,False))
+      k :: Data d => Mp m (d -> b) -> d -> Mp m b
       k (Mp c) y
         = Mp ( c >>= \(h,b) -> if b
                         then return (h y, b)
@@ -446,18 +459,24 @@ fromConstrB :: Data a
             -> a
 fromConstrB f = unID . gunfold k z
  where
+  k :: forall b r. Data b => ID (b -> r) -> ID r
   k c = ID (unID c f)
+ 
+  z :: forall r. r -> ID r
   z = ID
 
 
 -- | Monadic variation on 'fromConstrB'
-fromConstrM :: (Monad m, Data a)
+fromConstrM :: forall m a. (Monad m, Data a)
             => (forall d. Data d => m d)
             -> Constr
             -> m a
 fromConstrM f = gunfold k z
  where
+  k :: forall b r. Data b => m (b -> r) -> m r
   k c = do { c' <- c; b <- f; return (c' b) }
+
+  z :: forall r. r -> m r
   z = return
 
 
@@ -480,8 +499,9 @@ data DataType = DataType
 
               deriving Show
 
-
--- | Representation of constructors
+-- | Representation of constructors. Note that equality on constructors
+-- with different types may not work -- i.e. the constructors for 'False' and
+-- 'Nothing' may compare equal.
 data Constr = Constr
                         { conrep    :: ConstrRep
                         , constring :: String