X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;ds=sidebyside;f=ghc%2Fcompiler%2Fghci%2FInteractiveUI.hs;h=f4e0800427ad152f1922b18cabb2ce362b0a503e;hb=433e74b58ec9d389e39aa62c63599fada0bb75b2;hp=3c663ecfc8fee4873fa9b0ca1dc10510efff4f8a;hpb=b382ce6f044cbea2af7c2489bd8c0f95f7cc724c;p=ghc-hetmet.git

diff --git a/ghc/compiler/ghci/InteractiveUI.hs b/ghc/compiler/ghci/InteractiveUI.hs
index 3c663ec..f4e0800 100644
--- a/ghc/compiler/ghci/InteractiveUI.hs
+++ b/ghc/compiler/ghci/InteractiveUI.hs
@@ -1,5 +1,5 @@
 -----------------------------------------------------------------------------
--- $Id: InteractiveUI.hs,v 1.12 2000/11/22 11:12:52 simonmar Exp $
+-- $Id: InteractiveUI.hs,v 1.34 2001/02/07 10:45:43 simonmar Exp $
 --
 -- GHC Interactive User Interface
 --
@@ -13,23 +13,34 @@ module InteractiveUI (interactiveUI) where
 
 import CompManager
 import CmStaticInfo
+import ByteCodeLink
 import DriverFlags
-import DriverUtil
 import DriverState
+import DriverUtil
+import Type
 import Linker
+import Finder
 import Module
 import Outputable
-import Panic
 import Util
+import PprType		{- instance Outputable Type; do not delete -}
+import Panic		( GhcException(..) )
 
 import Exception
+#ifndef NO_READLINE
 import Readline
+#endif
 import IOExts
 
+import Numeric
+import List
 import System
+import CPUTime
 import Directory
 import IO
 import Char
+import Monad ( when )
+
 
 -----------------------------------------------------------------------------
 
@@ -41,23 +52,29 @@ ghciWelcomeMsg = "\
 \||   || ||   || ||     (|     Bug reports to: glasgow-haskell-bugs@haskell.org \n\ 
 \(|___|| ||   || (|__|) \\\\______________________________________________________\n"
 
-commands :: [(String, String -> GHCi ())]
+commands :: [(String, String -> GHCi Bool)]
 commands = [
-  ("add",	addModule),
-  ("cd",    	changeDirectory),
-  ("help",	help),
-  ("?",		help),
-  ("load",	loadModule),
-  ("module",	setContext),
-  ("reload",	reloadModule),
-  ("set",	setOptions),
-  ("type",	typeOfExpr),
+  ("add",	keepGoing addModule),
+  ("cd",    	keepGoing changeDirectory),
+  ("help",	keepGoing help),
+  ("?",		keepGoing help),
+  ("load",	keepGoing loadModule),
+  ("module",	keepGoing setContext),
+  ("reload",	keepGoing reloadModule),
+  ("set",	keepGoing setOptions),
+  ("type",	keepGoing typeOfExpr),
+  ("unset",	keepGoing unsetOptions),
   ("quit",	quit)
   ]
 
+keepGoing :: (String -> GHCi ()) -> (String -> GHCi Bool)
+keepGoing a str = a str >> return False
+
 shortHelpText = "use :? for help.\n"
 
 helpText = "\ 
+\ Commands available from the prompt:\n\ 
+\\  
 \   <expr>		evaluate <expr>\n\ 
 \   :add <filename>     add a module to the current set\n\ 
 \   :cd <dir>		change directory to <dir>\n\ 
@@ -66,13 +83,22 @@ helpText = "\
 \   :module <mod>	set the context for expression evaluation to <mod>\n\ 
 \   :reload		reload the current module set\n\ 
 \   :set <option> ...	set options\n\ 
+\   :unset <option> ...	unset options\n\ 
 \   :type <expr>	show the type of <expr>\n\ 
 \   :quit		exit GHCi\n\ 
 \   :!<command>		run the shell command <command>\n\ 
+\\ 
+\ Options for `:set' and `:unset':\n\ 
+\\ 
+\    +s                 print timing/memory stats after each evaluation\n\ 
+\    +t			print type after evaluation\n\ 
+\    +r			revert top-level expressions after each evaluation\n\ 
+\    -<flags>		most GHC command line flags can also be set here\n\ 
+\                         (eg. -v2, -fglasgow-exts, etc.)\n\ 
 \"
 
-interactiveUI :: CmState -> IO ()
-interactiveUI st = do
+interactiveUI :: CmState -> Maybe FilePath -> IO ()
+interactiveUI cmstate mod = do
    hPutStrLn stdout ghciWelcomeMsg
    hFlush stdout
    hSetBuffering stdout NoBuffering
@@ -81,78 +107,179 @@ interactiveUI st = do
    pkgs <- getPackageInfo
    linkPackages (reverse pkgs)
 
+   (cmstate, ok, mods) <-
+   	case mod of
+	     Nothing  -> return (cmstate, True, [])
+	     Just m -> cmLoadModule cmstate m
+
 #ifndef NO_READLINE
    Readline.initialize
 #endif
-   _ <- (unGHCi uiLoop) GHCiState{ modules = [],
-				   current_module = defaultCurrentModule,
-	  	                   target = Nothing,
-			           cmstate = st }
+
+   prel <- moduleNameToModule defaultCurrentModuleName
+   writeIORef defaultCurrentModule prel
+
+   dflags <- getDynFlags
+
+   (cmstate, maybe_stuff) <- cmGetExpr cmstate dflags False prel 
+		  		"PrelHandle.hFlush PrelHandle.stdout"
+   case maybe_stuff of
+	Nothing -> return ()
+	Just (hv,_,_) -> writeIORef flush_stdout hv
+   
+   (cmstate, maybe_stuff) <- cmGetExpr cmstate dflags False prel 
+		  		"PrelHandle.hFlush PrelHandle.stdout"
+   case maybe_stuff of
+	Nothing -> return ()
+	Just (hv,_,_) -> writeIORef flush_stderr hv
+   
+   let this_mod = case mods of 
+	  	      []   -> prel
+  	  	      m:ms -> m
+
+   (unGHCi runGHCi) GHCiState{ modules = mods,
+			      current_module = this_mod,
+	  	              target = mod,
+			      cmstate = cmstate,
+			      options = [ShowTiming],
+                              last_expr = Nothing}
    return ()
 
-uiLoop :: GHCi ()
-uiLoop = do
-  st <- getGHCiState
+
+runGHCi :: GHCi ()
+runGHCi = do
+  -- read in ./.ghci
+  dot_ghci <- io (IO.try (openFile "./.ghci" ReadMode))
+  case dot_ghci of
+	Left e -> return ()
+	Right hdl -> fileLoop hdl False
+  
+  -- read in ~/.ghci
+  home <- io (IO.try (getEnv "HOME"))
+  case home of
+   Left e  -> return ()
+   Right dir -> do
+  	dot_ghci <- io (IO.try (openFile (dir ++ "/.ghci") ReadMode))
+	case dot_ghci of
+	   Left e -> return ()
+	   Right hdl -> fileLoop hdl False
+
+  -- read commands from stdin
 #ifndef NO_READLINE
-  l <- io (readline (moduleNameUserString (current_module st) ++ "> "))
+  readlineLoop
 #else
-  l <- io (hGetLine stdin)
+  fileLoop stdin True
 #endif
-  case l of
-    Nothing -> exitGHCi
-    Just "" -> uiLoop
-    Just l  -> do
+
+  -- and finally, exit
+  io $ do putStrLn "Leaving GHCi." 
+
+
+fileLoop :: Handle -> Bool -> GHCi ()
+fileLoop hdl prompt = do
+   st <- getGHCiState
+   when prompt (io (hPutStr hdl (moduleUserString (current_module st) ++ "> ")))
+   l <- io (IO.try (hGetLine hdl))
+   case l of
+	Left e | isEOFError e -> return ()
+	       | otherwise    -> throw e
+	Right l -> 
+	  case remove_spaces l of
+	    "" -> fileLoop hdl prompt
+	    l  -> do quit <- runCommand l
+          	     if quit then return () else fileLoop hdl prompt
+
 #ifndef NO_READLINE
-          io (addHistory l)
+readlineLoop :: GHCi ()
+readlineLoop = do
+   st <- getGHCiState
+   l <- io (readline (moduleUserString (current_module st) ++ "> "))
+   case l of
+	Nothing -> return ()
+	Just l  ->
+	  case remove_spaces l of
+	    "" -> readlineLoop
+	    l  -> do
+        	  io (addHistory l)
+  	  	  quit <- runCommand l
+          	  if quit then return () else readlineLoop
 #endif
-  	  runCommand l
-	  uiLoop  
-
-exitGHCi = io $ do putStrLn "Leaving GHCi."; exitWith ExitSuccess
 
 -- Top level exception handler, just prints out the exception 
 -- and carries on.
+runCommand :: String -> GHCi Bool
 runCommand c = 
-  ghciHandle ( \other_exception ->io (putStrLn (show other_exception) )) $
+  ghciHandle ( 
+     \other_exception 
+        -> io (putStrLn (show other_exception)) >> return False
+  ) $
   ghciHandleDyn
     (\dyn -> case dyn of
 		PhaseFailed phase code ->
 			io ( putStrLn ("Phase " ++ phase ++ " failed (code "
 				        ++ show code ++ ")"))
 		Interrupted -> io (putStrLn "Interrupted.")
-		_ -> io (putStrLn (show (dyn :: BarfKind)))
+		_ -> io (putStrLn (show (dyn :: GhcException)))
+             >> return False
     ) $
    doCommand c
 
 doCommand (':' : command) = specialCommand command
+doCommand ('-':'-':_) = return False	-- comments, useful in scripts
 doCommand expr
+   = do expr_expanded <- expandExpr expr
+        -- io (putStrLn ( "Before: " ++ expr ++ "\nAfter:  " ++ expr_expanded))
+        expr_ok <- timeIt (do stuff <- evalExpr expr_expanded
+			      finishEvalExpr stuff)
+        when expr_ok (rememberExpr expr_expanded)
+        return False
+
+-- possibly print the type and revert CAFs after evaluating an expression
+finishEvalExpr Nothing = return False
+finishEvalExpr (Just (unqual,ty))
+ = do b <- isOptionSet ShowType
+      io (when b (printForUser stdout unqual (text "::" <+> ppr ty)))
+      b <- isOptionSet RevertCAFs
+      io (when b revertCAFs)
+      return True
+
+-- Returned Bool indicates whether or not the expr was successfully
+-- parsed, renamed and typechecked.
+evalExpr :: String -> GHCi (Maybe (PrintUnqualified,Type))
+evalExpr expr
+ | null (filter (not.isSpace) expr)
+ = return Nothing
+ | otherwise
  = do st <- getGHCiState
       dflags <- io (getDynFlags)
-      (new_cmstate, maybe_hvalue) <- 
-      	 io (cmGetExpr (cmstate st) dflags (current_module st) expr)
+      (new_cmstate, maybe_stuff) <- 
+      	 io (cmGetExpr (cmstate st) dflags True (current_module st) expr)
       setGHCiState st{cmstate = new_cmstate}
-      case maybe_hvalue of
-      	 Nothing -> return ()
-      	 Just hv -> io (cmRunExpr hv)
-{-
-  let (mod,'.':str) = break (=='.') expr
-  case cmLookupSymbol (mkOrig varName (mkModuleName mod) (_PK_ str)) (cmstate st) of
-	Nothing -> io (putStrLn "nothing.")
-	Just e  -> io (
-  return ()
--}
-
+      case maybe_stuff of
+      	 Nothing -> return Nothing
+      	 Just (hv, unqual, ty) -> do io (cmRunExpr hv)
+		 		     flushEverything
+		 		     return (Just (unqual,ty))
+
+flushEverything :: GHCi ()
+flushEverything
+   = io $ do flush_so <- readIORef flush_stdout
+     	     cmRunExpr flush_so
+     	     flush_se <- readIORef flush_stdout
+     	     cmRunExpr flush_se
+
+specialCommand :: String -> GHCi Bool
 specialCommand ('!':str) = shellEscape (dropWhile isSpace str)
 specialCommand str = do
   let (cmd,rest) = break isSpace str
   case [ (s,f) | (s,f) <- commands, prefixMatch cmd s ] of
-     []      -> io $ hPutStr stdout ("unknown command `:" ++ cmd ++ "'\n" 
-				    ++ shortHelpText)
+     []      -> io (hPutStr stdout ("unknown command `:" ++ cmd ++ "'\n" 
+		                    ++ shortHelpText) >> return False)
      [(_,f)] -> f (dropWhile isSpace rest)
-     cs      -> io $ hPutStrLn stdout ("prefix " ++ cmd ++ 
-			    	       " matches multiple commands (" ++ 
+     cs      -> io (hPutStrLn stdout ("prefix " ++ cmd ++ 
+			    	      " matches multiple commands (" ++ 
 	         	     	       foldr1 (\a b -> a ++ ',':b) (map fst cs)
-					 ++ ")")
+					 ++ ")") >> return False)
 
 noArgs c = io (hPutStrLn stdout ("command `:" ++ c ++ "' takes no arguments"))
 
@@ -170,24 +297,42 @@ setContext ""
   = throwDyn (OtherError "syntax: `:m <module>'")
 setContext m | not (isUpper (head m)) || not (all isAlphaNum (tail m))
   = throwDyn (OtherError ("strange looking module name: `" ++ m ++ "'"))
-setContext m
-  = do st <- getGHCiState
-       setGHCiState st{current_module = mkModuleName m}
+setContext mn
+  = do m <- io (moduleNameToModule (mkModuleName mn))
+       st <- getGHCiState
+       if (isHomeModule m && m `notElem` modules st)
+	  then throwDyn (OtherError (showSDoc (quotes (ppr (moduleName m))
+				<+> text "is not currently loaded, use :load")))
+	  else setGHCiState st{current_module = m}
+
+moduleNameToModule :: ModuleName -> IO Module
+moduleNameToModule mn
+ = do maybe_stuff <- findModule mn
+      case maybe_stuff of
+	 Nothing -> throwDyn (OtherError ("can't find module `"
+					    ++ moduleNameUserString mn ++ "'"))
+   	 Just (m,_) -> return m
 
 changeDirectory :: String -> GHCi ()
-changeDirectory = io . setCurrentDirectory
+changeDirectory d = io (setCurrentDirectory d)
 
 loadModule :: String -> GHCi ()
-loadModule path = do
+loadModule path = timeIt (loadModule' path)
+
+loadModule' path = do
   state <- getGHCiState
-  (new_cmstate, ok, mods) <- io (cmLoadModule (cmstate state) path)
+  cmstate1 <- io (cmUnload (cmstate state))
+  io (revertCAFs)			-- always revert CAFs on load.
+  (cmstate2, ok, mods) <- io (cmLoadModule cmstate1 path)
+
+  def_mod <- io (readIORef defaultCurrentModule)
 
-  let new_state = GHCiState {
-  			cmstate = new_cmstate,
+  let new_state = state{
+  			cmstate = cmstate2,
 			modules = mods,
 			current_module = case mods of 
-					   [] -> defaultCurrentModule
-					   xs -> last xs,
+					   [] -> def_mod
+					   xs -> head xs,
 			target = Just path
 		   }
   setGHCiState new_state
@@ -195,7 +340,7 @@ loadModule path = do
   let mod_commas 
 	| null mods = text "none."
 	| otherwise = hsep (
-	    punctuate comma (map (text.moduleNameUserString) mods)) <> text "."
+	    punctuate comma (map (text.moduleUserString) mods)) <> text "."
   case ok of
     False -> 
        io (putStrLn (showSDoc (text "Failed, modules loaded: " <> mod_commas)))
@@ -207,59 +352,193 @@ reloadModule "" = do
   state <- getGHCiState
   case target state of
    Nothing -> io (putStr "no current target\n")
-   Just path -> do (new_cmstate, ok, mod) 
-			<- io (cmLoadModule (cmstate state) path)
-  		   setGHCiState state{cmstate=new_cmstate}  
+   Just path
+      -> do io (revertCAFs)		-- always revert CAFs on reload.
+	    (new_cmstate, ok, mods) <- io (cmLoadModule (cmstate state) path)
+	    def_mod <- io (readIORef defaultCurrentModule)
+            setGHCiState 
+               state{cmstate=new_cmstate,
+                     modules = mods,
+                     current_module = case mods of 
+                                         [] -> def_mod
+                                         xs -> head xs
+                    }
+
 reloadModule _ = noArgs ":reload"
 
+typeOfExpr :: String -> GHCi ()
+typeOfExpr str 
+  = do st <- getGHCiState
+       dflags <- io (getDynFlags)
+       (new_cmstate, maybe_ty) <- io (cmGetExpr (cmstate st) dflags False
+					 (current_module st) str)
+       setGHCiState st{cmstate = new_cmstate}
+       case maybe_ty of
+	 Nothing -> return ()
+	 Just (_, unqual, ty) -> io (printForUser stdout unqual (ppr ty)) 
+
+quit :: String -> GHCi Bool
+quit _ = return True
+
+shellEscape :: String -> GHCi Bool
+shellEscape str = io (system str >> return False)
+
+----------------------------------------------------------------------------
+-- Code for `:set'
+
 -- set options in the interpreter.  Syntax is exactly the same as the
 -- ghc command line, except that certain options aren't available (-C,
 -- -E etc.)
 --
 -- This is pretty fragile: most options won't work as expected.  ToDo:
 -- figure out which ones & disallow them.
-setOptions :: String -> GHCi ()
-setOptions str =
-   io (do leftovers <- processArgs static_flags (words str) []
-	  dyn_flags <- readIORef v_InitDynFlags
-	  writeIORef v_DynFlags dyn_flags
-	  leftovers <- processArgs dynamic_flags leftovers []
-	  dyn_flags <- readIORef v_DynFlags
-	  writeIORef v_InitDynFlags dyn_flags
-          if (not (null leftovers))
-		then throwDyn (OtherError ("unrecognised flags: " ++ 
-						unwords leftovers))
-		else return ()
-   )
 
-typeOfExpr :: String -> GHCi ()
-typeOfExpr str 
+setOptions :: String -> GHCi ()
+setOptions ""
   = do st <- getGHCiState
-       dflags <- io (getDynFlags)
-       (st, maybe_ty) <- io (cmTypeExpr (cmstate st) dflags 
-				(current_module st) str)
-       case maybe_ty of
-	 Nothing -> return ()
-	 Just (unqual, ty) -> io (printForUser stdout unqual (ppr ty))
+       let opts = options st
+       io $ putStrLn (showSDoc (
+   	      text "options currently set: " <> 
+   	      if null opts
+   		   then text "none."
+   		   else hsep (map (\o -> char '+' <> text (optToStr o)) opts)
+   	   ))
+setOptions str
+  = do -- first, deal with the GHCi opts (+s, +t, etc.)
+       let opts = words str
+	   (minus_opts, rest1) = partition isMinus opts
+	   (plus_opts, rest2)  = partition isPlus rest1
+
+       if (not (null rest2)) 
+	  then io (putStrLn ("unknown option: `" ++ head rest2 ++ "'"))
+	  else do
+
+       mapM setOpt plus_opts
+
+       -- now, the GHC flags
+       io (do -- first, static flags
+	      leftovers <- processArgs static_flags minus_opts []
+
+	      -- then, dynamic flags
+	      dyn_flags <- readIORef v_InitDynFlags
+	      writeIORef v_DynFlags dyn_flags
+	      leftovers <- processArgs dynamic_flags leftovers []
+	      dyn_flags <- readIORef v_DynFlags
+	      writeIORef v_InitDynFlags dyn_flags
+
+              if (not (null leftovers))
+		 then throwDyn (OtherError ("unrecognised flags: " ++ 
+						unwords leftovers))
+		 else return ()
+         )
+
+unsetOptions :: String -> GHCi ()
+unsetOptions str
+  = do -- first, deal with the GHCi opts (+s, +t, etc.)
+       let opts = words str
+	   (minus_opts, rest1) = partition isMinus opts
+	   (plus_opts, rest2)  = partition isPlus rest1
+
+       if (not (null rest2)) 
+	  then io (putStrLn ("unknown option: `" ++ head rest2 ++ "'"))
+	  else do
+
+       mapM unsetOpt plus_opts
+ 
+       -- can't do GHC flags for now
+       if (not (null minus_opts))
+	  then throwDyn (OtherError "can't unset GHC command-line flags")
+	  else return ()
+
+isMinus ('-':s) = True
+isMinus _ = False
+
+isPlus ('+':s) = True
+isPlus _ = False
+
+setOpt ('+':str)
+  = case strToGHCiOpt str of
+	Nothing -> io (putStrLn ("unknown option: `" ++ str ++ "'"))
+	Just o  -> setOption o
+
+unsetOpt ('+':str)
+  = case strToGHCiOpt str of
+	Nothing -> io (putStrLn ("unknown option: `" ++ str ++ "'"))
+	Just o  -> unsetOption o
+
+strToGHCiOpt :: String -> (Maybe GHCiOption)
+strToGHCiOpt "s" = Just ShowTiming
+strToGHCiOpt "t" = Just ShowType
+strToGHCiOpt "r" = Just RevertCAFs
+strToGHCiOpt _   = Nothing
+
+optToStr :: GHCiOption -> String
+optToStr ShowTiming = "s"
+optToStr ShowType   = "t"
+optToStr RevertCAFs = "r"
 
-quit :: String -> GHCi ()
-quit _ = exitGHCi
+-----------------------------------------------------------------------------
+-- Code to do last-expression-entered stuff.  (a.k.a the $$ facility)
+
+-- Take a string and replace $$s in it with the last expr, if any.
+expandExpr :: String -> GHCi String
+expandExpr str
+   = do mle <- getLastExpr
+        return (outside mle str)
+     where
+        outside mle ('$':'$':cs)
+           = case mle of
+                Just le -> " (" ++ le ++ ") " ++ outside mle cs
+                Nothing -> outside mle cs
+
+        outside mle []           = []
+        outside mle ('"':str)    = '"' : inside2 mle str   -- "
+        outside mle ('\'':str)   = '\'' : inside1 mle str   -- '
+        outside mle (c:cs)       = c : outside mle cs
+
+        inside2 mle ('"':cs)  = '"' : outside mle cs   -- "
+        inside2 mle (c:cs)    = c : inside2 mle cs
+        inside2 mle []        = []
+
+        inside1 mle ('\'':cs) = '\'': outside mle cs
+        inside1 mle (c:cs)    = c : inside1 mle cs
+        inside1 mle []        = []
+
+
+rememberExpr :: String -> GHCi ()
+rememberExpr str
+   = do let cleaned = (clean . reverse . clean . reverse) str
+        let forget_me_not | null cleaned = Nothing
+                          | otherwise    = Just cleaned
+        setLastExpr forget_me_not
+     where
+        clean = dropWhile isSpace
 
-shellEscape :: String -> GHCi ()
-shellEscape str = io (system str >> return ())
 
 -----------------------------------------------------------------------------
 -- GHCi monad
 
 data GHCiState = GHCiState
      { 
-	modules	       :: [ModuleName],
-	current_module :: ModuleName,
+	modules	       :: [Module],
+	current_module :: Module,
 	target         :: Maybe FilePath,
-	cmstate        :: CmState
+	cmstate        :: CmState,
+	options        :: [GHCiOption],
+        last_expr      :: Maybe String
      }
 
-defaultCurrentModule = mkModuleName "Prelude"
+data GHCiOption 
+	= ShowTiming		-- show time/allocs after evaluation
+	| ShowType		-- show the type of expressions
+	| RevertCAFs		-- revert CAFs after every evaluation
+	deriving Eq
+
+defaultCurrentModuleName = mkModuleName "Prelude"
+GLOBAL_VAR(defaultCurrentModule, error "no defaultCurrentModule", Module)
+
+GLOBAL_VAR(flush_stdout, error "no flush_stdout", HValue)
+GLOBAL_VAR(flush_stderr, error "no flush_stdout", HValue)
 
 newtype GHCi a = GHCi { unGHCi :: GHCiState -> IO (GHCiState, a) }
 
@@ -270,6 +549,29 @@ instance Monad GHCi where
 getGHCiState   = GHCi $ \s -> return (s,s)
 setGHCiState s = GHCi $ \_ -> return (s,())
 
+isOptionSet :: GHCiOption -> GHCi Bool
+isOptionSet opt
+ = do st <- getGHCiState
+      return (opt `elem` options st)
+
+setOption :: GHCiOption -> GHCi ()
+setOption opt
+ = do st <- getGHCiState
+      setGHCiState (st{ options = opt : filter (/= opt) (options st) })
+
+unsetOption :: GHCiOption -> GHCi ()
+unsetOption opt
+ = do st <- getGHCiState
+      setGHCiState (st{ options = filter (/= opt) (options st) })
+
+getLastExpr :: GHCi (Maybe String)
+getLastExpr
+ = do st <- getGHCiState ; return (last_expr st)
+
+setLastExpr :: Maybe String -> GHCi ()
+setLastExpr last_expr
+ = do st <- getGHCiState ; setGHCiState (st{last_expr = last_expr})
+
 io m = GHCi $ \s -> m >>= \a -> return (s,a)
 
 ghciHandle h (GHCi m) = GHCi $ \s -> 
@@ -304,3 +606,34 @@ findFile (d:ds) obj = do
   let path = d ++ '/':obj
   b <- doesFileExist path
   if b then return path else findFile ds obj
+
+-----------------------------------------------------------------------------
+-- timing & statistics
+
+timeIt :: GHCi a -> GHCi a
+timeIt action
+  = do b <- isOptionSet ShowTiming
+       if not b 
+	  then action 
+	  else do allocs1 <- io $ getAllocations
+		  time1   <- io $ getCPUTime
+		  a <- action
+		  allocs2 <- io $ getAllocations
+		  time2   <- io $ getCPUTime
+		  io $ printTimes (allocs2 - allocs1) (time2 - time1)
+		  return a
+
+foreign import "getAllocations" getAllocations :: IO Int
+
+printTimes :: Int -> Integer -> IO ()
+printTimes allocs psecs
+   = do let secs = (fromIntegral psecs / (10^12)) :: Float
+	    secs_str = showFFloat (Just 2) secs
+	putStrLn (showSDoc (
+		 parens (text (secs_str "") <+> text "secs" <> comma <+> 
+			 int allocs <+> text "bytes")))
+
+-----------------------------------------------------------------------------
+-- reverting CAFs
+	
+foreign import revertCAFs :: IO ()	-- make it "safe", just in case