[project @ 2000-01-30 10:11:32 by simonmar]

[ghc-hetmet.git] / ghc / lib / std / PrelIOBase.lhs

diff --git a/ghc/lib/std/PrelIOBase.lhs b/ghc/lib/std/PrelIOBase.lhs
index bf7a64f..9f8aa77 100644 (file)
--- a/ghc/lib/std/PrelIOBase.lhs
+++ b/ghc/lib/std/PrelIOBase.lhs
@@ -1,5 +1,5 @@
 % -----------------------------------------------------------------------------
-% $Id: PrelIOBase.lhs,v 1.15 1999/11/26 16:26:32 simonmar Exp $
+% $Id: PrelIOBase.lhs,v 1.17 2000/01/30 10:11:32 simonmar Exp $
 % 
 % (c) The AQUA Project, Glasgow University, 1994-1998
 %
@@ -55,6 +55,23 @@ The IO Monad is just an instance of the ST monad, where the state is
 the real world.  We use the exception mechanism (in PrelException) to
 implement IO exceptions.
 
+NOTE: The IO representation is deeply wired in to various parts of the
+system.  The following list may or may not be exhaustive:
+
+Compiler  - types of various primitives in PrimOp.lhs
+
+RTS      - forceIO (StgMiscClosures.hc)
+         - catchzh_fast, (un)?blockAsyncExceptionszh_fast, raisezh_fast 
+           (Exceptions.hc)
+         - raiseAsync (Schedule.c)
+
+Prelude   - PrelIOBase.lhs, and several other places including
+           PrelException.lhs.
+
+Libraries - parts of hslibs/lang.
+
+--SDM
+
 \begin{code}
 #ifndef __HUGS__
 newtype IO a = IO (State# RealWorld -> (# State# RealWorld, a #))
@@ -75,10 +92,6 @@ instance  Monad IO  where
     m >>= k     = bindIO m k
     fail s     = error s -- not ioError?
 
-    -- not required but worth having around
-fixIO          :: (a -> IO a) -> IO a
-fixIO m         = stToIO (fixST (ioToST . m))
-
 liftIO :: IO a -> State# RealWorld -> STret RealWorld a
 liftIO (IO m) = \s -> case m s of (# s', r #) -> STret s' r