X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Fghci%2FInteractiveUI.hs;h=dd4343fa40994eac059f86ea5ed3cb68349604e7;hb=effc285ff0be62636148d66bb4bf0002baaf14e8;hp=282ad93f9092d7ed1ab6c0f97a6ed39f82cd4845;hpb=bc882daec931dcde171341f1fee32b45b17cc22e;p=ghc-hetmet.git

diff --git a/ghc/compiler/ghci/InteractiveUI.hs b/ghc/compiler/ghci/InteractiveUI.hs
index 282ad93..dd4343f 100644
--- a/ghc/compiler/ghci/InteractiveUI.hs
+++ b/ghc/compiler/ghci/InteractiveUI.hs
@@ -15,34 +15,32 @@ module InteractiveUI (
 
 -- The GHC interface
 import qualified GHC
-import GHC		( Session, verbosity, dopt, DynFlag(..),
+import GHC		( Session, verbosity, dopt, DynFlag(..), Target(..),
+			  TargetId(..),
 			  mkModule, pprModule, Type, Module, SuccessFlag(..),
-			  TyThing(..), Name, LoadHowMuch(..),
+			  TyThing(..), Name, LoadHowMuch(..), Phase,
 			  GhcException(..), showGhcException,
-			  CheckedModule(..) )
+			  CheckedModule(..), SrcLoc )
+import PprTyThing
 import Outputable
 
--- following all needed for :info... ToDo: remove
-import IfaceSyn		( IfaceDecl(..), IfaceClassOp(..), IfaceConDecls(..),
-			  IfaceConDecl(..), IfaceType,
-		   	  pprIfaceDeclHead, pprParendIfaceType,
-			  pprIfaceForAllPart, pprIfaceType )
-import FunDeps		( pprFundeps )
-import SrcLoc		( SrcLoc, pprDefnLoc )
-import OccName		( OccName, parenSymOcc, occNameUserString )
-import BasicTypes	( StrictnessMark(..), defaultFixity, failed, successIf )
+-- for createtags (should these come via GHC?)
+import Module		( moduleString )
+import Name		( nameSrcLoc, nameModule, nameOccName )
+import OccName		( pprOccName )
+import SrcLoc		( isGoodSrcLoc, srcLocFile, srcLocLine, srcLocCol )
 
 -- Other random utilities
+import Digraph		( flattenSCCs )
+import BasicTypes	( failed, successIf )
 import Panic 		( panic, installSignalHandlers )
 import Config
 import StaticFlags	( opt_IgnoreDotGhci )
 import Linker		( showLinkerState )
 import Util		( removeSpaces, handle, global, toArgs,
-			  looksLikeModuleName, prefixMatch )
-import ErrUtils		( printErrorsAndWarnings )
+			  looksLikeModuleName, prefixMatch, sortLe )
 
 #ifndef mingw32_HOST_OS
-import Util		( handle )
 import System.Posix
 #if __GLASGOW_HASKELL__ > 504
 	hiding (getEnv)
@@ -65,7 +63,7 @@ import Data.Dynamic
 import Numeric
 import Data.List
 import Data.Int		( Int64 )
-import Data.Maybe	( isJust )
+import Data.Maybe	( isJust, fromMaybe, catMaybes )
 import System.Cmd
 import System.CPUTime
 import System.Environment
@@ -106,10 +104,13 @@ builtin_commands = [
   ("info",      keepGoing info),
   ("load",	keepGoingPaths loadModule_),
   ("module",	keepGoing setContext),
+  ("main",	keepGoing runMain),
   ("reload",	keepGoing reloadModule),
   ("check",	keepGoing checkModule),
   ("set",	keepGoing setCmd),
   ("show",	keepGoing showCmd),
+  ("etags",	keepGoing createETagsFileCmd),
+  ("ctags",	keepGoing createCTagsFileCmd),
   ("type",	keepGoing typeOfExpr),
   ("kind",	keepGoing kindOfType),
   ("unset",	keepGoing unsetOptions),
@@ -138,6 +139,7 @@ helpText =
  "   :info [<name> ...]          display information about the given names\n" ++
  "   :load <filename> ...        load module(s) and their dependents\n" ++
  "   :module [+/-] [*]<mod> ...  set the context for expression evaluation\n" ++
+ "   :main [<arguments> ...]     run the main function with the given arguments\n" ++
  "   :reload                     reload the current module set\n" ++
  "\n" ++
  "   :set <option> ...           set options\n" ++
@@ -147,6 +149,8 @@ helpText =
  "   :show modules               show the currently loaded modules\n" ++
  "   :show bindings              show the current bindings made at the prompt\n" ++
  "\n" ++
+ "   :ctags [<file>]             create tags file for Vi (default: \"tags\")\n" ++
+ "   :etags [<file>]           	 create tags file for Emacs (defauilt: \"TAGS\")\n" ++
  "   :type <expr>                show the type of <expr>\n" ++
  "   :kind <type>                show the kind of <type>\n" ++
  "   :undef <cmd>                undefine user-defined command :<cmd>\n" ++
@@ -163,7 +167,7 @@ helpText =
  "                         (eg. -v2, -fglasgow-exts, etc.)\n"
 
 
-interactiveUI :: Session -> [FilePath] -> Maybe String -> IO ()
+interactiveUI :: Session -> [(FilePath, Maybe Phase)] -> Maybe String -> IO ()
 interactiveUI session srcs maybe_expr = do
 
    -- HACK! If we happen to get into an infinite loop (eg the user
@@ -195,13 +199,6 @@ interactiveUI session srcs maybe_expr = do
    Readline.initialize
 #endif
 
-#if defined(mingw32_HOST_OS)
-    -- The win32 Console API mutates the first character of 
-    -- type-ahead when reading from it in a non-buffered manner. Work
-    -- around this by flushing the input buffer of type-ahead characters.
-    -- 
-   GHC.ConsoleHandler.flushConsole stdin
-#endif
    startGHCi (runGHCi srcs maybe_expr)
 	GHCiState{ progname = "<interactive>",
 		   args = [],
@@ -214,7 +211,7 @@ interactiveUI session srcs maybe_expr = do
 
    return ()
 
-runGHCi :: [FilePath] -> Maybe String -> GHCi ()
+runGHCi :: [(FilePath, Maybe Phase)] -> Maybe String -> GHCi ()
 runGHCi paths maybe_expr = do
   let read_dot_files = not opt_IgnoreDotGhci
 
@@ -264,6 +261,18 @@ runGHCi paths maybe_expr = do
 
   case maybe_expr of
 	Nothing -> 
+#if defined(mingw32_HOST_OS)
+          do
+            -- The win32 Console API mutates the first character of 
+            -- type-ahead when reading from it in a non-buffered manner. Work
+            -- around this by flushing the input buffer of type-ahead characters,
+            -- but only if stdin is available.
+            flushed <- io (IO.try (GHC.ConsoleHandler.flushConsole stdin))
+            case flushed of 
+   	     Left err | isDoesNotExistError err -> return ()
+   		      | otherwise -> io (ioError err)
+   	     Right () -> return ()
+#endif
 	    -- enter the interactive loop
 	    interactiveLoop is_tty show_prompt
 	Just expr -> do
@@ -275,15 +284,18 @@ runGHCi paths maybe_expr = do
   io $ do when (verbosity dflags > 0) $ putStrLn "Leaving GHCi."
 
 
-interactiveLoop is_tty show_prompt = do
+interactiveLoop is_tty show_prompt =
   -- Ignore ^C exceptions caught here
   ghciHandleDyn (\e -> case e of 
-			Interrupted -> ghciUnblock (
+			Interrupted -> do
 #if defined(mingw32_HOST_OS)
-						io (putStrLn "") >> 
+				io (putStrLn "")
 #endif
-						interactiveLoop is_tty show_prompt)
-			_other      -> return ()) $ do
+				interactiveLoop is_tty show_prompt
+			_other      -> return ()) $ 
+
+  ghciUnblock $ do -- unblock necessary if we recursed from the 
+		   -- exception handler above.
 
   -- read commands from stdin
 #ifdef USE_READLINE
@@ -383,6 +395,11 @@ readlineLoop = do
 
 runCommand :: String -> GHCi Bool
 runCommand c = ghciHandle handler (doCommand c)
+  where 
+    doCommand (':' : command) = specialCommand command
+    doCommand stmt
+       = do timeIt (do nms <- runStmt stmt; finishEvalExpr nms)
+            return False
 
 -- This version is for the GHC command-line option -e.  The only difference
 -- from runCommand is that it catches the ExitException exception and
@@ -393,6 +410,14 @@ runCommandEval c = ghciHandle handleEval (doCommand c)
     handleEval e                    = do showException e
 				         io (exitWith (ExitFailure 1))
 
+    doCommand (':' : command) = specialCommand command
+    doCommand stmt
+       = do nms <- runStmt stmt
+	    case nms of 
+		Nothing -> io (exitWith (ExitFailure 1))
+		  -- failure to run the command causes exit(1) for ghc -e.
+		_       -> finishEvalExpr nms
+
 -- This is the exception handler for exceptions generated by the
 -- user's code; it normally just prints out the exception.  The
 -- handler must be recursive, in case showing the exception causes
@@ -419,29 +444,26 @@ showException (DynException dyn) =
 showException other_exception
   = io (putStrLn ("*** Exception: " ++ show other_exception))
 
-doCommand (':' : command) = specialCommand command
-doCommand stmt
-   = do timeIt (do nms <- runStmt stmt; finishEvalExpr nms)
-        return False
-
-runStmt :: String -> GHCi [Name]
+runStmt :: String -> GHCi (Maybe [Name])
 runStmt stmt
- | null (filter (not.isSpace) stmt) = return []
+ | null (filter (not.isSpace) stmt) = return (Just [])
  | otherwise
  = do st <- getGHCiState
       session <- getSession
       result <- io $ withProgName (progname st) $ withArgs (args st) $
 	     	     GHC.runStmt session stmt
       case result of
-	GHC.RunFailed      -> return []
+	GHC.RunFailed      -> return Nothing
 	GHC.RunException e -> throw e  -- this is caught by runCommand(Eval)
-	GHC.RunOk names    -> return names
+	GHC.RunOk names    -> return (Just names)
 
 -- possibly print the type and revert CAFs after evaluating an expression
-finishEvalExpr names
+finishEvalExpr mb_names
  = do b <- isOptionSet ShowType
       session <- getSession
-      when b (mapM_ (showTypeOfName session) names)
+      case mb_names of
+	Nothing    -> return ()      
+	Just names -> when b (mapM_ (showTypeOfName session) names)
 
       flushInterpBuffers
       io installSignalHandlers
@@ -467,17 +489,13 @@ specialCommand ('!':str) = shellEscape (dropWhile isSpace str)
 specialCommand str = do
   let (cmd,rest) = break isSpace str
   cmds <- io (readIORef commands)
-  case [ (s,f) | (s,f) <- cmds, prefixMatch cmd s ] of
-     []      -> io (hPutStr stdout ("unknown command ':" ++ cmd ++ "'\n" 
+  -- look for exact match first, then the first prefix match
+  case [ (s,f) | (s,f) <- cmds, cmd == s ] of
+     (_,f):_ -> f (dropWhile isSpace rest)
+     [] -> case [ (s,f) | (s,f) <- cmds, prefixMatch cmd s ] of
+     		[] -> io (hPutStr stdout ("unknown command ':" ++ cmd ++ "'\n" 
 		                    ++ shortHelpText) >> return False)
-     [(_,f)] -> f (dropWhile isSpace rest)
-     cs      -> io (hPutStrLn stdout ("prefix " ++ cmd ++ 
-			    	      " matches multiple commands (" ++ 
-	         	     	       foldr1 (\a b -> a ++ ',':b) (map fst cs)
-					 ++ ")") >> return False)
-
-noArgs c = throwDyn (CmdLineError ("command '" ++ c ++ "' takes no arguments"))
-
+     		(_,f):_ -> f (dropWhile isSpace rest)
 
 -----------------------------------------------------------------------------
 -- To flush buffers for the *interpreted* computation we need
@@ -532,135 +550,47 @@ info s  = do { let names = words s
 	     ; let exts = dopt Opt_GlasgowExts dflags
 	     ; mapM_ (infoThing exts session) names }
   where
-    infoThing exts session name
-	= do { stuff <- io (GHC.getInfo session name)
-	     ; unqual <- io (GHC.getPrintUnqual session)
-	     ; io (putStrLn (showSDocForUser unqual $
-     		   vcat (intersperse (text "") (map (showThing exts) stuff)))) }
-
-showThing :: Bool -> GHC.GetInfoResult -> SDoc
-showThing exts (wanted_str, thing, fixity, src_loc, insts) 
-    = vcat [ showWithLoc src_loc (showDecl exts want_name thing),
-	     show_fixity fixity,
-	     vcat (map show_inst insts)]
+    infoThing exts session str = io $ do
+	names <- GHC.parseName session str
+	let filtered = filterOutChildren names
+	mb_stuffs <- mapM (GHC.getInfo session) filtered
+	unqual <- GHC.getPrintUnqual session
+	putStrLn (showSDocForUser unqual $
+     		   vcat (intersperse (text "") $
+		   [ pprInfo exts stuff | Just stuff <-  mb_stuffs ]))
+
+  -- Filter out names whose parent is also there Good
+  -- example is '[]', which is both a type and data
+  -- constructor in the same type
+filterOutChildren :: [Name] -> [Name]
+filterOutChildren names = filter (not . parent_is_there) names
+ where parent_is_there n 
+	 | Just p <- GHC.nameParent_maybe n = p `elem` names
+	 | otherwise		           = False
+
+pprInfo exts (thing, fixity, insts)
+  =  pprTyThingInContextLoc exts thing 
+  $$ show_fixity fixity
+  $$ vcat (map GHC.pprInstance insts)
   where
-    want_name occ = wanted_str == occNameUserString occ
-
     show_fixity fix 
-	| fix == defaultFixity = empty
-	| otherwise            = ppr fix <+> text wanted_str
-
-    show_inst (inst_ty, loc)
-	= showWithLoc loc (ptext SLIT("instance") <+> ppr inst_ty)
-
-showWithLoc :: SrcLoc -> SDoc -> SDoc
-showWithLoc loc doc 
-    = hang doc 2 (char '\t' <> comment <+> pprDefnLoc loc)
-		-- The tab tries to make them line up a bit
-  where
-    comment = ptext SLIT("--")
-
-
--- Now there is rather a lot of goop just to print declarations in a
--- civilised way with "..." for the parts we are less interested in.
-
-showDecl :: Bool -> (OccName -> Bool) -> IfaceDecl -> SDoc
-showDecl exts want_name (IfaceForeign {ifName = tc})
-  = ppr tc <+> ptext SLIT("is a foreign type")
-
-showDecl exts want_name (IfaceId {ifName = var, ifType = ty})
-  = ppr var <+> dcolon <+> showIfaceType exts ty 
-
-showDecl exts want_name (IfaceSyn {ifName = tycon, ifTyVars = tyvars, ifSynRhs = mono_ty})
-  = hang (ptext SLIT("type") <+> pprIfaceDeclHead [] tycon tyvars)
-       2 (equals <+> ppr mono_ty)
-
-showDecl exts want_name (IfaceData {ifName = tycon, 
-		     ifTyVars = tyvars, ifCons = condecls, ifCtxt = context})
-  = hang (pp_nd <+> pprIfaceDeclHead context tycon tyvars)
-       2 (add_bars (ppr_trim show_con cs))
-  where
-    show_con (IfVanillaCon { ifConOcc = con_name, ifConInfix = is_infix, ifConArgTys = tys, 
-			     ifConStricts = strs, ifConFields = flds})
-	| want_name tycon || want_name con_name || any want_name flds
-	= Just (show_guts con_name is_infix tys_w_strs flds)
-	| otherwise = Nothing
-	where
-	  tys_w_strs = tys `zip` (strs ++ repeat NotMarkedStrict)
-    show_con (IfGadtCon { ifConOcc = con_name, ifConTyVars = tvs, ifConCtxt = theta, 
-			  ifConArgTys = arg_tys, ifConResTys = res_tys, ifConStricts = strs })
-	| want_name tycon || want_name con_name
-	= Just (ppr_bndr con_name <+> colon <+> pprIfaceForAllPart tvs theta pp_tau)
-	| otherwise = Nothing
-	where
-	  tys_w_strs = arg_tys `zip` (strs ++ repeat NotMarkedStrict)
-	  pp_tau = foldr add pp_res_ty tys_w_strs
-	  pp_res_ty = ppr_bndr tycon <+> hsep (map pprParendIfaceType res_tys)
-	  add bty pp_ty = ppr_bangty bty <+> arrow <+> pp_ty
-
-    show_guts con True [ty1, ty2] flds = sep [ppr_bangty ty1, ppr con, ppr_bangty ty2]
-    show_guts con _ tys []   = ppr_bndr con <+> sep (map ppr_bangty tys)
-    show_guts con _ tys flds 
-	= ppr_bndr con <+> braces (sep (punctuate comma (ppr_trim show_fld (tys `zip` flds))))
-	where
-	  show_fld (bty, fld) | want_name tycon || want_name con || want_name fld
-			      = Just (ppr_bndr fld <+> dcolon <+> ppr_bangty bty)
-			      | otherwise = Nothing
-
-    (pp_nd, cs) = case condecls of
-		    IfAbstractTyCon 	   -> (ptext SLIT("data"),   [])
-		    IfDataTyCon cs         -> (ptext SLIT("data"),   cs)
-		    IfNewTyCon c    	   -> (ptext SLIT("newtype"),[c])
-
-    add_bars []      = empty
-    add_bars [c]     = equals <+> c
-    add_bars (c:cs)  = equals <+> sep (c : map (char '|' <+>) cs)
-
-    ppr_bangty (ty, str) = ppr_str str <> pprParendIfaceType ty
-    ppr_str MarkedStrict    = char '!'
-    ppr_str MarkedUnboxed   = ptext SLIT("!!")
-    ppr_str NotMarkedStrict = empty
-
-showDecl exts want_name (IfaceClass {ifCtxt = context, ifName = clas, ifTyVars = tyvars, 
-		      ifFDs = fds, ifSigs = sigs})
-  = hang (ptext SLIT("class") <+> pprIfaceDeclHead context clas tyvars
-		<+> pprFundeps fds <+> opt_where)
-       2 (vcat (ppr_trim show_op sigs))
-  where
-    opt_where | null sigs = empty
-	      | otherwise = ptext SLIT("where")
-    show_op (IfaceClassOp op dm ty) 
-	| want_name clas || want_name op 
-	= Just (ppr_bndr op <+> dcolon <+> showIfaceType exts ty)
-	| otherwise
-	= Nothing
-
-showIfaceType :: Bool -> IfaceType -> SDoc
-showIfaceType True  ty = pprIfaceType ty -- -fglasgow-exts: print with the foralls
-showIfaceType False ty = ppr ty	    -- otherwise, print without the foralls
-
-ppr_trim :: (a -> Maybe SDoc) -> [a] -> [SDoc]
-ppr_trim show xs
-  = snd (foldr go (False, []) xs)
-  where
-    go x (eliding, so_far)
-	| Just doc <- show x = (False, doc : so_far)
-	| otherwise = if eliding then (True, so_far)
-		                 else (True, ptext SLIT("...") : so_far)
-
-ppr_bndr :: OccName -> SDoc
--- Wrap operators in ()
-ppr_bndr occ = parenSymOcc occ (ppr occ)
-
+	| fix == GHC.defaultFixity = empty
+	| otherwise		   = ppr fix <+> ppr (GHC.getName thing)
 
 -----------------------------------------------------------------------------
 -- Commands
 
+runMain :: String -> GHCi ()
+runMain args = do
+  let ss = concat $ intersperse "," (map (\ s -> ('"':s)++"\"") (toArgs args))
+  runCommand $ '[': ss ++ "] `System.Environment.withArgs` main"
+  return ()
+
 addModule :: [FilePath] -> GHCi ()
 addModule files = do
   io (revertCAFs)			-- always revert CAFs on load/add.
   files <- mapM expandPath files
-  targets <- mapM (io . GHC.guessTarget) files
+  targets <- mapM (\m -> io (GHC.guessTarget m Nothing)) files
   session <- getSession
   io (mapM_ (GHC.addTarget session) targets)
   ok <- io (GHC.load session LoadAllTargets)
@@ -674,7 +604,7 @@ changeDirectory dir = do
 	io $ putStr "Warning: changing directory causes all loaded modules to be unloaded,\nbecause the search path has changed.\n"
   io (GHC.setTargets session [])
   io (GHC.load session LoadAllTargets)
-  setContextAfterLoad []
+  setContextAfterLoad session []
   io (GHC.workingDirectoryChanged session)
   dir <- expandPath dir
   io (setCurrentDirectory dir)
@@ -701,7 +631,7 @@ defineMacro s = do
   case maybe_hv of
      Nothing -> return ()
      Just hv -> io (writeIORef commands --
-		    ((macro_name, keepGoing (runMacro hv)) : cmds))
+		    (cmds ++ [(macro_name, keepGoing (runMacro hv))]))
 
 runMacro :: GHC.HValue{-String -> IO String-} -> String -> GHCi ()
 runMacro fun s = do
@@ -722,13 +652,13 @@ undefineMacro macro_name = do
   io (writeIORef commands (filter ((/= macro_name) . fst) cmds))
 
 
-loadModule :: [FilePath] -> GHCi SuccessFlag
+loadModule :: [(FilePath, Maybe Phase)] -> GHCi SuccessFlag
 loadModule fs = timeIt (loadModule' fs)
 
 loadModule_ :: [FilePath] -> GHCi ()
-loadModule_ fs = do loadModule fs; return ()
+loadModule_ fs = do loadModule (zip fs (repeat Nothing)); return ()
 
-loadModule' :: [FilePath] -> GHCi SuccessFlag
+loadModule' :: [(FilePath, Maybe Phase)] -> GHCi SuccessFlag
 loadModule' files = do
   session <- getSession
 
@@ -737,8 +667,10 @@ loadModule' files = do
   io (GHC.load session LoadAllTargets)
 
   -- expand tildes
-  files <- mapM expandPath files
-  targets <- io (mapM GHC.guessTarget files)
+  let (filenames, phases) = unzip files
+  exp_filenames <- mapM expandPath filenames
+  let files' = zip exp_filenames phases
+  targets <- io (mapM (uncurry GHC.guessTarget) files')
 
   -- NOTE: we used to do the dependency anal first, so that if it
   -- fails we didn't throw away the current set of modules.  This would
@@ -754,7 +686,7 @@ checkModule :: String -> GHCi ()
 checkModule m = do
   let modl = mkModule m
   session <- getSession
-  result <- io (GHC.checkModule session modl printErrorsAndWarnings)
+  result <- io (GHC.checkModule session modl)
   case result of
     Nothing -> io $ putStrLn "Nothing"
     Just r  -> io $ putStrLn (showSDoc (
@@ -783,19 +715,39 @@ reloadModule m = do
 afterLoad ok session = do
   io (revertCAFs)  -- always revert CAFs on load.
   graph <- io (GHC.getModuleGraph session)
-  let mods = map GHC.ms_mod graph
-  mods' <- filterM (io . GHC.isLoaded session) mods
-  setContextAfterLoad mods'
-  modulesLoadedMsg ok mods'
+  graph' <- filterM (io . GHC.isLoaded session . GHC.ms_mod) graph
+  setContextAfterLoad session graph'
+  modulesLoadedMsg ok (map GHC.ms_mod graph')
 
-setContextAfterLoad [] = do
-  session <- getSession
+setContextAfterLoad session [] = do
   io (GHC.setContext session [] [prelude_mod])
-setContextAfterLoad (m:_) = do
-  session <- getSession
-  b <- io (GHC.moduleIsInterpreted session m)
-  if b then io (GHC.setContext session [m] []) 
-       else io (GHC.setContext session []  [m])
+setContextAfterLoad session ms = do
+  -- load a target if one is available, otherwise load the topmost module.
+  targets <- io (GHC.getTargets session)
+  case [ m | Just m <- map (findTarget ms) targets ] of
+	[]    -> 
+	  let graph' = flattenSCCs (GHC.topSortModuleGraph True ms Nothing) in
+	  load_this (last graph')	  
+	(m:_) -> 
+	  load_this m
+ where
+   findTarget ms t
+    = case filter (`matches` t) ms of
+	[]    -> Nothing
+	(m:_) -> Just m
+
+   summary `matches` Target (TargetModule m) _
+	= GHC.ms_mod summary == m
+   summary `matches` Target (TargetFile f _) _ 
+	| Just f' <- GHC.ml_hs_file (GHC.ms_location summary)	= f == f'
+   summary `matches` target
+	= False
+
+   load_this summary | m <- GHC.ms_mod summary = do
+	b <- io (GHC.moduleIsInterpreted session m)
+	if b then io (GHC.setContext session [m] []) 
+       	     else io (GHC.setContext session []  [prelude_mod,m])
+
 
 modulesLoadedMsg :: SuccessFlag -> [Module] -> GHCi ()
 modulesLoadedMsg ok mods = do
@@ -838,6 +790,117 @@ shellEscape :: String -> GHCi Bool
 shellEscape str = io (system str >> return False)
 
 -----------------------------------------------------------------------------
+-- create tags file for currently loaded modules.
+
+createETagsFileCmd, createCTagsFileCmd :: String -> GHCi ()
+
+createCTagsFileCmd ""   = ghciCreateTagsFile CTags "tags"
+createCTagsFileCmd file = ghciCreateTagsFile CTags file
+
+createETagsFileCmd ""    = ghciCreateTagsFile ETags "TAGS"
+createETagsFileCmd file  = ghciCreateTagsFile ETags file
+
+data TagsKind = ETags | CTags
+
+ghciCreateTagsFile :: TagsKind -> FilePath -> GHCi ()
+ghciCreateTagsFile kind file = do
+  session <- getSession
+  io $ createTagsFile session kind file
+
+-- ToDo: 
+-- 	- remove restriction that all modules must be interpreted
+--	  (problem: we don't know source locations for entities unless
+--	  we compiled the module.
+--
+--	- extract createTagsFile so it can be used from the command-line
+--	  (probably need to fix first problem before this is useful).
+--
+createTagsFile :: Session -> TagsKind -> FilePath -> IO ()
+createTagsFile session tagskind tagFile = do
+  graph <- GHC.getModuleGraph session
+  let ms = map GHC.ms_mod graph
+      tagModule m = do 
+        is_interpreted <- GHC.moduleIsInterpreted session m
+        -- should we just skip these?
+        when (not is_interpreted) $
+          throwDyn (CmdLineError ("module '" ++ moduleString m ++ "' is not interpreted"))
+
+        mbModInfo <- GHC.getModuleInfo session m
+        let unqual 
+	      | Just modinfo <- mbModInfo,
+		Just unqual <- GHC.modInfoPrintUnqualified modinfo = unqual
+	      | otherwise = GHC.alwaysQualify
+
+        case mbModInfo of 
+          Just modInfo -> return $! listTags unqual modInfo 
+          _            -> return []
+
+  mtags <- mapM tagModule ms
+  either_res <- collateAndWriteTags tagskind tagFile $ concat mtags
+  case either_res of
+    Left e  -> hPutStrLn stderr $ ioeGetErrorString e
+    Right _ -> return ()
+
+listTags :: PrintUnqualified -> GHC.ModuleInfo -> [TagInfo]
+listTags unqual modInfo =
+	   [ tagInfo unqual name loc 
+           | name <- GHC.modInfoExports modInfo
+           , let loc = nameSrcLoc name
+           , isGoodSrcLoc loc
+           ]
+
+type TagInfo = (String -- tag name
+               ,String -- file name
+               ,Int    -- line number
+               ,Int    -- column number
+               )
+
+-- get tag info, for later translation into Vim or Emacs style
+tagInfo :: PrintUnqualified -> Name -> SrcLoc -> TagInfo
+tagInfo unqual name loc
+    = ( showSDocForUser unqual $ pprOccName (nameOccName name)
+      , showSDocForUser unqual $ ftext (srcLocFile loc)
+      , srcLocLine loc
+      , srcLocCol loc
+      )
+
+collateAndWriteTags :: TagsKind -> FilePath -> [TagInfo] -> IO (Either IOError ())
+collateAndWriteTags CTags file tagInfos = do -- ctags style, Vim et al
+  let tags = unlines $ sortLe (<=) $ nub $ map showTag tagInfos
+  IO.try (writeFile file tags)
+collateAndWriteTags ETags file tagInfos = do -- etags style, Emacs/XEmacs
+  let byFile op (_,f1,_,_) (_,f2,_,_) = f1 `op` f2
+      groups = groupBy (byFile (==)) $ sortLe (byFile (<=)) tagInfos
+  tagGroups <- mapM tagFileGroup groups 
+  IO.try (writeFile file $ concat tagGroups)
+  where
+    tagFileGroup group@[] = throwDyn (CmdLineError "empty tag file group??")
+    tagFileGroup group@((_,fileName,_,_):_) = do
+      file <- readFile fileName -- need to get additional info from sources..
+      let byLine (_,_,l1,_) (_,_,l2,_) = l1 <= l2
+          sortedGroup = sortLe byLine group
+          tags = unlines $ perFile sortedGroup 1 0 $ lines file
+      return $ "\x0c\n" ++ fileName ++ "," ++ show (length tags) ++ "\n" ++ tags
+    perFile (tagInfo@(tag,file,lNo,colNo):tags) count pos (line:lines) | lNo>count =
+      perFile (tagInfo:tags) (count+1) (pos+length line) lines
+    perFile (tagInfo@(tag,file,lNo,colNo):tags) count pos lines@(line:_) | lNo==count =
+      showETag tagInfo line pos : perFile tags count pos lines
+    perFile tags count pos lines = []
+
+-- simple ctags format, for Vim et al
+showTag :: TagInfo -> String
+showTag (tag,file,lineNo,colNo)
+    =  tag ++ "\t" ++ file ++ "\t" ++ show lineNo
+
+-- etags format, for Emacs/XEmacs
+showETag :: TagInfo -> String -> Int -> String
+showETag (tag,file,lineNo,colNo) line charPos
+    =  take colNo line ++ tag
+    ++ "\x7f" ++ tag
+    ++ "\x01" ++ show lineNo
+    ++ "," ++ show charPos
+
+-----------------------------------------------------------------------------
 -- Browsing a module's contents
 
 browseCmd :: String -> GHCi ()
@@ -860,16 +923,29 @@ browseModule m exports_only = do
   (as,bs) <- io (GHC.getContext s)
   io (if exports_only then GHC.setContext s [] [prelude_mod,modl]
 		      else GHC.setContext s [modl] [])
+  unqual <- io (GHC.getPrintUnqual s)
   io (GHC.setContext s as bs)
 
-  things <- io (GHC.browseModule s modl exports_only)
-  unqual <- io (GHC.getPrintUnqual s)
+  mb_mod_info <- io $ GHC.getModuleInfo s modl
+  case mb_mod_info of
+    Nothing -> throwDyn (CmdLineError ("unknown module: " ++ m))
+    Just mod_info -> do
+        let names
+	       | exports_only = GHC.modInfoExports mod_info
+	       | otherwise    = fromMaybe [] (GHC.modInfoTopLevelScope mod_info)
 
-  dflags <- getDynFlags
-  let exts = dopt Opt_GlasgowExts dflags
-  io (putStrLn (showSDocForUser unqual (
-   	 vcat (map (showDecl exts (const True)) things)
-      )))
+	    filtered = filterOutChildren names
+	
+        things <- io $ mapM (GHC.lookupName s) filtered
+
+        dflags <- getDynFlags
+	let exts = dopt Opt_GlasgowExts dflags
+	io (putStrLn (showSDocForUser unqual (
+		vcat (map (pprTyThingInContext exts) (catMaybes things))
+	   )))
+	-- ToDo: modInfoInstances currently throws an exception for
+	-- package modules.  When it works, we can do this:
+	--	$$ vcat (map GHC.pprInstance (GHC.modInfoInstances mod_info))
 
 -----------------------------------------------------------------------------
 -- Setting the module context