add Control.Monad.Instances to nhc98 build

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

diff --git a/Data/Bits.hs b/Data/Bits.hs
index d33f7ee..4564bce 100644 (file)
--- a/Data/Bits.hs
+++ b/Data/Bits.hs
@@ -9,11 +9,11 @@
 -- Stability   :  experimental
 -- Portability :  portable
 --
---  This module defines bitwise operations for signed and unsigned
---  integers.  Instances of the class 'Bits' for the 'Int' and
---  'Integer' types are available from this module, and instances for
---  explicitly sized integral types are available from the
---  "Data.Int" and "Data.Word" modules.
+-- This module defines bitwise operations for signed and unsigned
+-- integers.  Instances of the class 'Bits' for the 'Int' and
+-- 'Integer' types are available from this module, and instances for
+-- explicitly sized integral types are available from the
+-- "Data.Int" and "Data.Word" modules.
 --
 -----------------------------------------------------------------------------
 
@@ -66,6 +66,10 @@ The 'Bits' class defines bitwise operations over integral types.
 
 * Bits are numbered from 0 with bit 0 being the least
   significant bit.
+
+Minimal complete definition: '.&.', '.|.', 'xor', 'complement',
+('shift' or ('shiftL' and 'shiftR')), ('rotate' or ('rotateL' and 'rotateR')),
+'bitSize' and 'isSigned'.
 -}
 class Num a => Bits a where
     -- | Bitwise \"and\"
@@ -188,6 +192,8 @@ class Num a => Bits a where
     x `rotateR` i = x `rotate` (-i)
 
 instance Bits Int where
+    {-# INLINE shift #-}
+
 #ifdef __GLASGOW_HASKELL__
     (I# x#) .&.   (I# y#)  = I# (word2Int# (int2Word# x# `and#` int2Word# y#))
     (I# x#) .|.   (I# y#)  = I# (word2Int# (int2Word# x# `or#`  int2Word# y#))
@@ -197,8 +203,8 @@ instance Bits Int where
         | i# >=# 0#        = I# (x# `iShiftL#` i#)
         | otherwise        = I# (x# `iShiftRA#` negateInt# i#)
     (I# x#) `rotate` (I# i#) =
-        I# (word2Int# ((x'# `shiftL#` i'#) `or#`
-                       (x'# `shiftRL#` (wsib -# i'#))))
+        I# (word2Int# ((x'# `uncheckedShiftL#` i'#) `or#`
+                       (x'# `uncheckedShiftRL#` (wsib -# i'#))))
         where
         x'# = int2Word# x#
         i'# = word2Int# (int2Word# i# `and#` int2Word# (wsib -# 1#))