-- This is written in Haskell.
{--
HBase -- general-purpose libraries for Haskell
Copyright (C) 2002 Ashley Yakeley <ashley@semantic.org>

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
--}

-- | This module is not included in HBase,
-- you have to import it separately.
module HBase.Debug
	(
	module HBase.Debug,
	unsafePerformIO
	) where
	{
	import HBase;
	import System.IO.Unsafe(unsafePerformIO);
	import qualified System.IO;

	-- | This will typically crash if you're coercing to a different type.
	unsafeCoerce :: a -> b;
	unsafeCoerce a = unsafePerformIO (do
		{
		set r (Just a);
		Just b <- get r;
		return b;
		}) where
		{
		r :: IORef (Maybe c);
		r = unsafePerformIO (newStd Nothing);
		};

	unsafeTypedCoerce :: (Type b) -> a -> b;
	unsafeTypedCoerce _ = unsafeCoerce;

	unsafeCoerceIO :: (Monad m) =>
	 IO a -> m a;
	unsafeCoerceIO = unsafeCoerce;

	debugPrint :: String -> IO ();
	debugPrint s = System.IO.hPutStrLn System.IO.stderr s;

	debugPrintValue :: (Show a) => String -> a -> IO ();
	debugPrintValue s a = debugPrint (s ++ ": " ++ (show a));

	unsafePrintValue :: (Show a) => String -> a -> a;
	unsafePrintValue s a = unsafePerformIO (do
		{
		debugPrintValue s a;
		return a;
		});

	unsafePrintCoercedValue :: (Show b) => (Type b) -> String -> a -> a;
	unsafePrintCoercedValue t s a = unsafePerformIO (do
		{
		debugPrintValue s (unsafeTypedCoerce t a);
		return a;
		});

	seqReturn :: (Monad m) => a -> m ();
	seqReturn a = seq a (return ());

	debugSource :: (Show a,LiftedMonad IO m) =>
	 m a -> m a;
	debugSource ma = do
		{
		a <- ma;
		lift (debugPrint (show a));
		return a;
		};
	}