[project @ 2005-03-14 15:22:51 by simonmar]

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

diff --git a/GHC/IOBase.lhs b/GHC/IOBase.lhs
index 6fa596a..0a3cfca 100644 (file)
--- a/GHC/IOBase.lhs
+++ b/GHC/IOBase.lhs
@@ -1,5 +1,5 @@
 \begin{code}
-{-# OPTIONS -fno-implicit-prelude #-}
+{-# OPTIONS_GHC -fno-implicit-prelude #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  GHC.IOBase
@@ -14,14 +14,41 @@
 --
 -----------------------------------------------------------------------------
 
-module GHC.IOBase where
-
+-- #hide
+module GHC.IOBase(
+    IO(..), unIO, failIO, liftIO, bindIO, thenIO, returnIO, 
+    unsafePerformIO, unsafeInterleaveIO,
+  
+       -- To and from from ST
+    stToIO, ioToST, unsafeIOToST,
+
+       -- References
+    IORef(..), newIORef, readIORef, writeIORef, 
+    IOArray(..), newIOArray, readIOArray, writeIOArray, unsafeReadIOArray, unsafeWriteIOArray,
+    MVar(..),
+
+       -- Handles, file descriptors,
+    FilePath,  
+    Handle(..), Handle__(..), HandleType(..), IOMode(..), FD, 
+    isReadableHandleType, isWritableHandleType, showHandle,
+  
+       -- Buffers
+    Buffer(..), RawBuffer, BufferState(..), BufferList(..), BufferMode(..),
+    bufferIsWritable, bufferEmpty, bufferFull, 
+
+       -- Exceptions
+    Exception(..), ArithException(..), AsyncException(..), ArrayException(..),
+    stackOverflow, heapOverflow, throw, throwIO, ioException, 
+    IOError, IOException(..), IOErrorType(..), ioError, userError,
+    ExitCode(..) 
+  ) where
+       
 import GHC.ST
 import GHC.Arr -- to derive Ix class
 import GHC.Enum -- to derive Enum class
 import GHC.STRef
 import GHC.Base
-import GHC.Num -- To get fromInteger etc, needed because of -fno-implicit-prelude
+--  import GHC.Num     -- To get fromInteger etc, needed because of -fno-implicit-prelude
 import Data.Maybe  ( Maybe(..) )
 import GHC.Show
 import GHC.List
@@ -122,6 +149,12 @@ stToIO (ST m) = IO m
 ioToST       :: IO a -> ST RealWorld a
 ioToST (IO m) = (ST m)
 
+-- This relies on IO and ST having the same representation modulo the
+-- constraint on the type of the state
+--
+unsafeIOToST        :: IO a -> ST s a
+unsafeIOToST (IO io) = ST $ \ s -> (unsafeCoerce# io) s
+
 -- ---------------------------------------------------------------------------
 -- Unsafe IO operations
 
@@ -260,6 +293,15 @@ instance Eq (MVar a) where
 -- enough information to identify the handle for debugging.  A handle is
 -- equal according to '==' only to itself; no attempt
 -- is made to compare the internal state of different handles for equality.
+--
+-- GHC note: a 'Handle' will be automatically closed when the garbage
+-- collector detects that it has become unreferenced by the program.
+-- However, relying on this behaviour is not generally recommended:
+-- the garbage collector is unpredictable.  If possible, use explicit
+-- an explicit 'hClose' to close 'Handle's when they are no longer
+-- required.  GHC does not currently attempt to free up file
+-- descriptors when they have run out, it is your responsibility to
+-- ensure that this doesn't happen.
 
 data Handle 
   = FileHandle                         -- A normal handle to a file
@@ -553,6 +595,10 @@ data Exception
        -- ^The current thread was executing a call to
        -- 'Control.Concurrent.MVar.takeMVar' that could never return,
        -- because there are no other references to this 'MVar'.
+  | BlockedIndefinitely
+       -- ^The current thread was waiting to retry an atomic memory transaction
+       -- that could never become possible to complete because there are no other
+       -- threads referring to any of teh TVars involved.
   | Deadlock
        -- ^There are no runnable threads, so the program is
        -- deadlocked.  The 'Deadlock' exception is
@@ -690,6 +736,7 @@ instance Show Exception where
   showsPrec _ (DynException _err)        = showString "unknown exception"
   showsPrec _ (AsyncException e)        = shows e
   showsPrec _ (BlockedOnDeadMVar)       = showString "thread blocked indefinitely"
+  showsPrec _ (BlockedIndefinitely)     = showString "thread blocked indefinitely"
   showsPrec _ (NonTermination)           = showString "<<loop>>"
   showsPrec _ (Deadlock)                 = showString "<<deadlock>>"