[project @ 2005-10-21 10:39:56 by ross]

conformant Show and Read instances

diff --git a/Data/IntSet.hs b/Data/IntSet.hs
index 4dc1bf7..c41ed17 100644 (file)
--- a/Data/IntSet.hs
+++ b/Data/IntSet.hs
@@ -104,6 +104,7 @@ import qualified List
 -}
 
 #if __GLASGOW_HASKELL__
+import Text.Read (Lexeme(Ident), lexP, parens, prec, readPrec)
 import Data.Generics.Basics
 import Data.Generics.Instances
 #endif
@@ -582,7 +583,8 @@ instance Ord IntSet where
   Show
 --------------------------------------------------------------------}
 instance Show IntSet where
-  showsPrec d s  = showSet (toList s)
+  showsPrec p xs = showParen (p > 10) $
+    showString "fromList " . shows (toList xs)
 
 showSet :: [Int] -> ShowS
 showSet []     
@@ -594,6 +596,22 @@ showSet (x:xs)
     showTail (x:xs) = showChar ',' . shows x . showTail xs
 
 {--------------------------------------------------------------------
+  Read
+--------------------------------------------------------------------}
+instance Read IntSet where
+#ifdef __GLASGOW_HASKELL__
+  readPrec = parens $ prec 10 $ do
+    Ident "fromList" <- lexP
+    xs <- readPrec
+    return (fromList xs)
+#else
+  readsPrec p = readParen (p > 10) $ \ r -> do
+    ("fromList",s) <- lex
+    (xs,t) <- reads
+    return (fromList xs,t)
+#endif
+
+{--------------------------------------------------------------------
   Typeable
 --------------------------------------------------------------------}
 

diff --git a/Data/Set.hs b/Data/Set.hs
index 33641de..fd09eb0 100644 (file)
--- a/Data/Set.hs
+++ b/Data/Set.hs
@@ -123,6 +123,7 @@ import qualified List
 -}
 
 #if __GLASGOW_HASKELL__
+import Text.Read (Lexeme(Ident), lexP, parens, prec, readPrec)
 import Data.Generics.Basics
 import Data.Generics.Instances
 #endif
@@ -512,7 +513,8 @@ instance Ord a => Ord (Set a) where
   Show
 --------------------------------------------------------------------}
 instance Show a => Show (Set a) where
-  showsPrec d s  = showSet (toAscList s)
+  showsPrec p xs = showParen (p > 10) $
+    showString "fromList " . shows (toList xs)
 
 showSet :: (Show a) => [a] -> ShowS
 showSet []     
@@ -527,17 +529,18 @@ showSet (x:xs)
   Read
 --------------------------------------------------------------------}
 instance (Read a, Ord a) => Read (Set a) where
-  readsPrec _ = readParen False $ \ r ->
-            [(fromList xs,t)     | ("{",s) <- lex r,
-                                   (xs,t)  <- readl s]
-      where readl s  = [([],t)   | ("}",t) <- lex s] ++
-                       [(x:xs,u) | (x,t)   <- reads s
-                                 , (xs,u)  <- readl' t]
-            readl' s = [([],t)   | ("}",t) <- lex s] ++
-                       [(x:xs,v) | (",",t) <- lex s
-                                 , (x,u)   <- reads t
-                                 , (xs,v)  <- readl' u]
-    
+#ifdef __GLASGOW_HASKELL__
+  readPrec = parens $ prec 10 $ do
+    Ident "fromList" <- lexP
+    xs <- readPrec
+    return (fromList xs)
+#else
+  readsPrec p = readParen (p > 10) $ \ r -> do
+    ("fromList",s) <- lex
+    (xs,t) <- reads
+    return (fromList xs,t)
+#endif
+
 {--------------------------------------------------------------------
   Typeable/Data
 --------------------------------------------------------------------}