[project @ 2003-04-17 15:23:37 by simonpj]

[ghc-base.git] / GHC / IOBase.lhs

diff --git a/GHC/IOBase.lhs b/GHC/IOBase.lhs
index 54ec69f..cf3c5eb 100644 (file)
--- a/GHC/IOBase.lhs
+++ b/GHC/IOBase.lhs
@@ -123,7 +123,7 @@ ioToST (IO m) = (ST m)
 -- Unsafe IO operations
 
 {-|
-This is the "back door" into the 'IO' monad, allowing
+This is the \"back door\" into the 'IO' monad, allowing
 'IO' computation to be performed at any time.  For
 this to be safe, the 'IO' computation should be
 free of side effects and independent of its environment.
@@ -406,6 +406,42 @@ writeIORef  :: IORef a -> a -> IO ()
 writeIORef (IORef var) v = stToIO (writeSTRef var v)
 
 -- ---------------------------------------------------------------------------
+-- | An 'IOArray' is a mutable, boxed, non-strict array in the 'IO' monad.  
+-- The type arguments are as follows:
+--
+--  * @i@: the index type of the array (should be an instance of @Ix@)
+--
+--  * @e@: the element type of the array.
+--
+-- 
+
+newtype IOArray i e = IOArray (STArray RealWorld i e) deriving Eq
+
+-- |Build a new 'IOArray'
+newIOArray :: Ix i => (i,i) -> e -> IO (IOArray i e)
+{-# INLINE newIOArray #-}
+newIOArray lu init  = stToIO $ do {marr <- newSTArray lu init; return (IOArray marr)}
+
+-- | Read a value from an 'IOArray'
+unsafeReadIOArray  :: Ix i => IOArray i e -> Int -> IO e
+{-# INLINE unsafeReadIOArray #-}
+unsafeReadIOArray (IOArray marr) i = stToIO (unsafeReadSTArray marr i)
+
+-- | Write a new value into an 'IOArray'
+unsafeWriteIOArray :: Ix i => IOArray i e -> Int -> e -> IO ()
+{-# INLINE unsafeWriteIOArray #-}
+unsafeWriteIOArray (IOArray marr) i e = stToIO (unsafeWriteSTArray marr i e)
+
+-- | Read a value from an 'IOArray'
+readIOArray  :: Ix i => IOArray i e -> i -> IO e
+readIOArray (IOArray marr) i = stToIO (readSTArray marr i)
+
+-- | Write a new value into an 'IOArray'
+writeIOArray :: Ix i => IOArray i e -> i -> e -> IO ()
+writeIOArray (IOArray marr) i e = stToIO (writeSTArray marr i e)
+
+
+-- ---------------------------------------------------------------------------
 -- Show instance for Handles
 
 -- handle types are 'show'n when printing error msgs, so
@@ -715,7 +751,7 @@ data IOException
                                     -- the error.
      ioe_type     :: IOErrorType,    -- what it was.
      ioe_location :: String,        -- location.
-     ioe_descr    :: String,         -- error type specific information.
+     ioe_description :: String,      -- error type specific information.
      ioe_filename :: Maybe FilePath  -- filename the error is related to.
    }
 
@@ -751,7 +787,7 @@ instance Eq IOErrorType where
    x == y = 
      case x of
        DynIOError{} -> False -- from a strictness POV, compatible with a derived Eq inst?
-       _ -> getTag# x ==# getTag# y
+       _ -> getTag x ==# getTag y
  
 instance Show IOErrorType where
   showsPrec _ e =