X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Fghci%2FInteractiveUI.hs;h=af0faad30855783c68ba570ca5a26ebfef04f37f;hb=1965e001f7e023563c1d8925c4f75f63989a8720;hp=8915badcaa876c4bb186b652733b07290b29488b;hpb=f3c0c2571a40d667cbe57ac1442b1d5ebaead0e0;p=ghc-hetmet.git

diff --git a/ghc/compiler/ghci/InteractiveUI.hs b/ghc/compiler/ghci/InteractiveUI.hs
index 8915bad..af0faad 100644
--- a/ghc/compiler/ghci/InteractiveUI.hs
+++ b/ghc/compiler/ghci/InteractiveUI.hs
@@ -1,5 +1,5 @@
 -----------------------------------------------------------------------------
--- $Id: InteractiveUI.hs,v 1.66 2001/05/04 16:36:38 simonmar Exp $
+-- $Id: InteractiveUI.hs,v 1.90 2001/08/16 10:54:22 simonmar Exp $
 --
 -- GHC Interactive User Interface
 --
@@ -8,13 +8,16 @@
 -----------------------------------------------------------------------------
 
 {-# OPTIONS -#include "Linker.h" #-}
+{-# OPTIONS -#include "SchedAPI.h" #-}
 module InteractiveUI ( interactiveUI, ghciWelcomeMsg ) where
 
 #include "../includes/config.h"
 #include "HsVersions.h"
 
+import Packages
 import CompManager
-import CmStaticInfo
+import HscTypes		( GhciMode(..), TyThing(..) )
+import MkIface          ( ifaceTyCls )
 import ByteCodeLink
 import DriverFlags
 import DriverState
@@ -22,13 +25,23 @@ import DriverUtil
 import Linker
 import Finder		( flushPackageCache )
 import Util
-import Name		( Name )
+import Id		( isRecordSelector, recordSelectorFieldLabel, 
+			  isDataConWrapId, idName )
+import Class		( className )
+import TyCon		( tyConName, tyConClass_maybe )
+import FieldLabel	( fieldLabelTyCon )
+import SrcLoc		( isGoodSrcLoc )
+import Name		( Name, isHomePackageName, nameSrcLoc, NamedThing(..) )
+import BasicTypes	( defaultFixity )
 import Outputable
-import CmdLineOpts	( DynFlag(..), dopt_unset )
+import CmdLineOpts	( DynFlag(..), getDynFlags, saveDynFlags, restoreDynFlags, dopt_unset )
 import Panic		( GhcException(..) )
 import Config
 
+#ifndef mingw32_TARGET_OS
 import Posix
+#endif
+
 import Exception
 import Dynamic
 #if HAVE_READLINE_HEADERS && HAVE_READLINE_LIBS
@@ -54,7 +67,7 @@ import CString		( peekCString )
 ghciWelcomeMsg = "\ 
 \   ___         ___ _\n\ 
 \  / _ \\ /\\  /\\/ __(_)\n\ 
-\ / /_\\// /_/ / /  | |      GHC Interactive, version " ++ cProjectVersion ++ ", For Haskell 98.\n\ 
+\ / /_\\// /_/ / /  | |      GHC Interactive, version " ++ cProjectVersion ++ ", for Haskell 98.\n\ 
 \/ /_\\\\/ __  / /___| |      http://www.haskell.org/ghc/\n\ 
 \\\____/\\/ /_/\\____/|_|      Type :? for help.\n"
 
@@ -67,6 +80,7 @@ builtin_commands = [
   ("def",	keepGoing defineMacro),
   ("help",	keepGoing help),
   ("?",		keepGoing help),
+  ("info",      keepGoing info),
   ("load",	keepGoing loadModule),
   ("module",	keepGoing setContext),
   ("reload",	keepGoing reloadModule),
@@ -84,20 +98,22 @@ shortHelpText = "use :? for help.\n"
 
 helpText = "\ 
 \ Commands available from the prompt:\n\ 
-\\  
-\   <stmt>		evaluate/run <stmt>\n\ 
-\   :cd <dir>		change directory to <dir>\n\ 
-\   :def <cmd> <expr>   define a command :<cmd>\n\ 
-\   :help, :?		display this list of commands\n\ 
-\   :load <filename>    load a module (and it dependents)\n\ 
-\   :module <mod>	set the context for expression evaluation to <mod>\n\ 
-\   :reload		reload the current module set\n\ 
-\   :set <option> ...	set options\n\ 
-\   :undef <name> 	undefine user-defined command :<name>\n\ 
-\   :type <expr>	show the type of <expr>\n\ 
-\   :unset <option> ...	unset options\n\ 
-\   :quit		exit GHCi\n\ 
-\   :!<command>		run the shell command <command>\n\ 
+\\
+\   <stmt>		   evaluate/run <stmt>\n\ 
+\   :add <filename> ...    add module(s) to the current target set\n\ 
+\   :cd <dir>		   change directory to <dir>\n\ 
+\   :def <cmd> <expr>      define a command :<cmd>\n\ 
+\   :help, :?		   display this list of commands\n\ 
+\   :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 to <mod>\n\ 
+\   :reload		   reload the current module set\n\ 
+\   :set <option> ...	   set options\n\ 
+\   :undef <cmd> 	   undefine user-defined command :<cmd>\n\ 
+\   :type <expr>	   show the type of <expr>\n\ 
+\   :unset <option> ...	   unset options\n\ 
+\   :quit		   exit GHCi\n\ 
+\   :!<command>		   run the shell command <command>\n\ 
 \\ 
 \ Options for `:set' and `:unset':\n\ 
 \\ 
@@ -107,10 +123,9 @@ helpText = "\
 \    -<flags>		most GHC command line flags can also be set here\n\ 
 \                         (eg. -v2, -fglasgow-exts, etc.)\n\ 
 \"
- --ToDo   :add <filename>     add a module to the current set\n\ 
 
-interactiveUI :: CmState -> Maybe FilePath -> [LibrarySpec] -> IO ()
-interactiveUI cmstate mod cmdline_libs = do
+interactiveUI :: CmState -> [FilePath] -> [LibrarySpec] -> IO ()
+interactiveUI cmstate paths cmdline_libs = do
    hFlush stdout
    hSetBuffering stdout NoBuffering
 
@@ -120,9 +135,9 @@ interactiveUI cmstate mod cmdline_libs = do
    linkPackages cmdline_libs pkgs
 
    (cmstate, ok, mods) <-
-   	case mod of
-	     Nothing  -> return (cmstate, True, [])
-	     Just m -> cmLoadModule cmstate m
+   	case paths of
+	     [] -> return (cmstate, True, [])
+	     _  -> cmLoadModule cmstate paths
 
 #if HAVE_READLINE_HEADERS && HAVE_READLINE_LIBS
    Readline.initialize
@@ -142,39 +157,49 @@ interactiveUI cmstate mod cmdline_libs = do
 	Just hval -> writeIORef flush_stdout (unsafeCoerce# hval :: IO ())
 	_ -> panic "interactiveUI:stdout"
 
-   (unGHCi runGHCi) GHCiState{ target = mod,
-			       cmstate = cmstate,
-			       options = [] }
+   startGHCi runGHCi GHCiState{ targets = paths,
+			        cmstate = cmstate,
+			        options = [] }
+
+#if HAVE_READLINE_HEADERS && HAVE_READLINE_LIBS
+   Readline.resetTerminal Nothing
+#endif
+
    return ()
 
 
 runGHCi :: GHCi ()
 runGHCi = do
-  -- Read in ./.ghci.
-  let file = "./.ghci"
-  exists <- io (doesFileExist file)
-  when exists $ do
-     dir_ok  <- io (checkPerms ".")
-     file_ok <- io (checkPerms file)
-     when (dir_ok && file_ok) $ do
-   	either_hdl <- io (IO.try (openFile "./.ghci" ReadMode))
-   	case either_hdl of
-   	   Left e    -> return ()
-   	   Right hdl -> fileLoop hdl False
-  
-  -- Read in $HOME/.ghci
-  either_dir <- io (IO.try (getEnv "HOME"))
-  case either_dir of
-     Left e -> return ()
-     Right dir -> do
-	cwd <- io (getCurrentDirectory)
-    	when (dir /= cwd) $ do
-	   let file = dir ++ "/.ghci"
-	   ok <- io (checkPerms file)
-       	   either_hdl <- io (IO.try (openFile file ReadMode))
-	   case either_hdl of
-		Left e    -> return ()
-		Right hdl -> fileLoop hdl False
+  read_dot_files <- io (readIORef v_Read_DotGHCi)
+
+  when (read_dot_files) $ do
+    -- Read in ./.ghci.
+    let file = "./.ghci"
+    exists <- io (doesFileExist file)
+    when exists $ do
+       dir_ok  <- io (checkPerms ".")
+       file_ok <- io (checkPerms file)
+       when (dir_ok && file_ok) $ do
+  	  either_hdl <- io (IO.try (openFile "./.ghci" ReadMode))
+  	  case either_hdl of
+  	     Left e    -> return ()
+  	     Right hdl -> fileLoop hdl False
+    
+  when (read_dot_files) $ do
+    -- Read in $HOME/.ghci
+    either_dir <- io (IO.try (getEnv "HOME"))
+    case either_dir of
+       Left e -> return ()
+       Right dir -> do
+  	  cwd <- io (getCurrentDirectory)
+  	  when (dir /= cwd) $ do
+  	     let file = dir ++ "/.ghci"
+  	     ok <- io (checkPerms file)
+  	     when ok $ do
+  	       either_hdl <- io (IO.try (openFile file ReadMode))
+  	       case either_hdl of
+  		  Left e    -> return ()
+  		  Right hdl -> fileLoop hdl False
 
   -- read commands from stdin
 #if HAVE_READLINE_HEADERS && HAVE_READLINE_LIBS
@@ -191,15 +216,17 @@ runGHCi = do
 -- and aren't world writable.  Otherwise, we could be accidentally 
 -- running code planted by a malicious third party.
 
--- Furthermore, We only read ./.ghci if both . and ./.ghci are
--- owned by the current user and aren't writable by anyone else.  I
--- think this is sufficient: we don't need to check .. and
--- ../.. etc. because "."  always refers to the same directory while a
--- process is running.
+-- Furthermore, We only read ./.ghci if . is owned by the current user
+-- and isn't writable by anyone else.  I think this is sufficient: we
+-- don't need to check .. and ../.. etc. because "."  always refers to
+-- the same directory while a process is running.
 
 checkPerms :: String -> IO Bool
 checkPerms name =
   handle (\_ -> return False) $ do
+#ifdef mingw32_TARGET_OS
+     doesFileExist name
+#else
      st <- getFileStatus name
      me <- getRealUserID
      if fileOwner st /= me then do
@@ -214,6 +241,7 @@ checkPerms name =
    			  " is writable by someone else, IGNORING!"
    	       return False
    	  else return True
+#endif
 
 fileLoop :: Handle -> Bool -> GHCi ()
 fileLoop hdl prompt = do
@@ -260,27 +288,28 @@ readlineLoop = do
 -- and carries on.
 runCommand :: String -> GHCi Bool
 runCommand c = 
-  ghciHandle ( \exception -> 
-	(case exception of
-	   DynException dyn -> 
-	      case fromDynamic dyn of
-		Nothing -> io (putStrLn ("*** Exception: (unknown)"))
-		Just ghc_ex -> 
-		  case ghc_ex of
-		    PhaseFailed phase code ->
-			io ( putStrLn ("Phase " ++ phase ++ " failed (code "
-				        ++ show code ++ ")"))
-		    Interrupted -> io (putStrLn "Interrupted.")
-			-- omit the location for CmdLineError
-		    CmdLineError s -> io (putStrLn s)
-		    other -> io (putStrLn (show (ghc_ex :: GhcException)))
-
-	   other -> io (putStrLn ("*** Exception: " ++ show exception))
-
-	) >> return False
-     ) $
-
-   doCommand c
+  ghciHandle ( \exception -> do
+		flushEverything
+		showException exception
+		return False
+	     ) $
+  doCommand c
+
+showException (DynException dyn) =
+  case fromDynamic dyn of
+    Nothing -> 
+	io (putStrLn ("*** Exception: (unknown)"))
+    Just (PhaseFailed phase code) ->
+	io (putStrLn ("Phase " ++ phase ++ " failed (code "
+		       ++ show code ++ ")"))
+    Just Interrupted ->
+	io (putStrLn "Interrupted.")
+    Just (CmdLineError s) -> 
+	io (putStrLn s)	 -- omit the location for CmdLineError
+    Just other_ghc_ex ->
+	io (putStrLn (show other_ghc_ex))
+showException other_exception
+  = io (putStrLn ("*** Exception: " ++ show other_exception))
 
 doCommand (':' : command) = specialCommand command
 doCommand stmt
@@ -295,7 +324,7 @@ runStmt stmt
  = return Nothing
  | otherwise
  = do st <- getGHCiState
-      dflags <- io (getDynFlags)
+      dflags <- io getDynFlags
       let dflags' = dopt_unset dflags Opt_WarnUnusedBinds
       (new_cmstate, names) <- io (cmRunStmt (cmstate st) dflags' stmt)
       setGHCiState st{cmstate = new_cmstate}
@@ -350,14 +379,77 @@ noArgs c = throwDyn (CmdLineError ("command `" ++ c ++ "' takes no arguments"))
 help :: String -> GHCi ()
 help _ = io (putStr helpText)
 
+info :: String -> GHCi ()
+info "" = throwDyn (CmdLineError "syntax: `:i <thing-you-want-info-about>'")
+info s = do
+  let names = words s
+  state <- getGHCiState
+  dflags <- io getDynFlags
+  let 
+    infoThings cms [] = return cms
+    infoThings cms (name:names) = do
+      (cms, unqual, stuff) <- io (cmInfoThing cms dflags name)
+      io (putStrLn (showSDocForUser unqual (
+	    vcat (intersperse (text "") (map showThing stuff))))
+         )
+      infoThings cms names
+
+    showThing (ty_thing, fixity) 
+	= vcat [ text "-- " <> showTyThing ty_thing, 
+		 showFixity fixity (getName ty_thing),
+	         ppr (ifaceTyCls ty_thing) ]
+
+    showFixity fix name
+	| fix == defaultFixity = empty
+	| otherwise            = ppr fix <+> ppr name
+
+    showTyThing (AClass cl) 
+       = hcat [ppr cl, text " is a class", showSrcLoc (className cl)]
+    showTyThing (ATyCon ty)
+       = hcat [ppr ty, text " is a type constructor", showSrcLoc (tyConName ty)]
+    showTyThing (AnId   id)
+       = hcat [ppr id, text " is a ", idDescr id, showSrcLoc (idName id)]
+
+    idDescr id
+       | isRecordSelector id = 
+		case tyConClass_maybe (fieldLabelTyCon (
+				recordSelectorFieldLabel id)) of
+			Nothing -> text "record selector"
+			Just c  -> text "method in class " <> ppr c
+       | isDataConWrapId id  = text "data constructor"
+       | otherwise           = text "variable"
+
+	-- also print out the source location for home things
+    showSrcLoc name
+	| isHomePackageName name && isGoodSrcLoc loc
+	= hsep [ text ", defined at", ppr loc ]
+	| otherwise
+	= empty
+	where loc = nameSrcLoc name
+
+  cms <- infoThings (cmstate state) names
+  setGHCiState state{ cmstate = cms }
+  return ()
+
+
 addModule :: String -> GHCi ()
-addModule _ = throwDyn (InstallationError ":add not implemented")
+addModule str = do
+  let files = words str
+  state <- getGHCiState
+  dflags <- io (getDynFlags)
+  io (revertCAFs)			-- always revert CAFs on load/add.
+  let new_targets = files ++ targets state 
+  (cmstate1, ok, mods) <- io (cmLoadModule (cmstate state) new_targets)
+  setGHCiState state{ cmstate = cmstate1, targets = new_targets }
+  modulesLoadedMsg ok mods
 
 setContext :: String -> GHCi ()
 setContext ""
   = throwDyn (CmdLineError "syntax: `:m <module>'")
-setContext m | not (isUpper (head m)) || not (all isAlphaNum (tail m))
+setContext m | not (isUpper (head m)) || not (all isAlphaNumEx (tail m))
   = throwDyn (CmdLineError ("strange looking module name: `" ++ m ++ "'"))
+    where
+       isAlphaNumEx c = isAlphaNum c || c == '_'
 setContext str
   = do st <- getGHCiState
        new_cmstate <- io (cmSetContext (cmstate st) str)
@@ -387,7 +479,7 @@ defineMacro s = do
 
   -- compile the expression
   st <- getGHCiState
-  dflags <- io (getDynFlags)
+  dflags <- io getDynFlags
   (new_cmstate, maybe_hv) <- io (cmCompileExpr (cmstate st) dflags new_expr)
   setGHCiState st{cmstate = new_cmstate}
   case maybe_hv of
@@ -414,28 +506,27 @@ undefineMacro macro_name = do
   io (writeIORef commands (filter ((/= macro_name) . fst) cmds))
 
 loadModule :: String -> GHCi ()
-loadModule path = timeIt (loadModule' path)
+loadModule str = timeIt (loadModule' str)
 
-loadModule' path = do
+loadModule' str = do
+  let files = words str
   state <- getGHCiState
-  dflags <- io (getDynFlags)
+  dflags <- io getDynFlags
   cmstate1 <- io (cmUnload (cmstate state) dflags)
+  setGHCiState state{ cmstate = cmstate1, targets = [] }
   io (revertCAFs)			-- always revert CAFs on load.
-  (cmstate2, ok, mods) <- io (cmLoadModule cmstate1 path)
-  let new_state = state{ cmstate = cmstate2,
-			 target = Just path
-		       }
-  setGHCiState new_state
+  (cmstate2, ok, mods) <- io (cmLoadModule cmstate1 files)
+  setGHCiState state{ cmstate = cmstate2, targets = files }
   modulesLoadedMsg ok mods
 
 reloadModule :: String -> GHCi ()
 reloadModule "" = do
   state <- getGHCiState
-  case target state of
-   Nothing -> io (putStr "no current target\n")
-   Just path
+  case targets state of
+   [] -> io (putStr "no current target\n")
+   paths
       -> do io (revertCAFs)		-- always revert CAFs on reload.
-	    (new_cmstate, ok, mods) <- io (cmLoadModule (cmstate state) path)
+	    (new_cmstate, ok, mods) <- io (cmLoadModule (cmstate state) paths)
             setGHCiState state{ cmstate=new_cmstate }
 	    modulesLoadedMsg ok mods
 
@@ -457,7 +548,7 @@ modulesLoadedMsg ok mods = do
 typeOfExpr :: String -> GHCi ()
 typeOfExpr str 
   = do st <- getGHCiState
-       dflags <- io (getDynFlags)
+       dflags <- io getDynFlags
        (new_cmstate, maybe_tystr) <- io (cmTypeOfExpr (cmstate st) dflags str)
        setGHCiState st{cmstate = new_cmstate}
        case maybe_tystr of
@@ -506,11 +597,9 @@ setOptions str
 
       -- then, dynamic flags
       io $ do 
-	dyn_flags <- readIORef v_InitDynFlags
-        writeIORef v_DynFlags dyn_flags
+	restoreDynFlags
         leftovers <- processArgs dynamic_flags leftovers []
-        dyn_flags <- readIORef v_DynFlags
-        writeIORef v_InitDynFlags dyn_flags
+	saveDynFlags
 
         if (not (null leftovers))
 		then throwDyn (CmdLineError ("unrecognised flags: " ++ 
@@ -565,9 +654,9 @@ optToStr RevertCAFs = "r"
 
 newPackages new_pkgs = do
   state <- getGHCiState
-  dflags <- io (getDynFlags)
+  dflags <- io getDynFlags
   cmstate1 <- io (cmUnload (cmstate state) dflags)
-  setGHCiState state{ cmstate = cmstate1, target = Nothing }
+  setGHCiState state{ cmstate = cmstate1, targets = [] }
 
   io $ do
     pkgs <- getPackageInfo
@@ -581,7 +670,7 @@ newPackages new_pkgs = do
 
 data GHCiState = GHCiState
      { 
-	target         :: Maybe FilePath,
+	targets        :: [FilePath],
 	cmstate        :: CmState,
 	options        :: [GHCiOption]
      }
@@ -595,14 +684,17 @@ data GHCiOption
 GLOBAL_VAR(flush_stdout, error "no flush_stdout", IO ())
 GLOBAL_VAR(flush_stderr, error "no flush_stdout", IO ())
 
-newtype GHCi a = GHCi { unGHCi :: GHCiState -> IO (GHCiState, a) }
+newtype GHCi a = GHCi { unGHCi :: IORef GHCiState -> IO a }
+
+startGHCi :: GHCi a -> GHCiState -> IO a
+startGHCi g state = do ref <- newIORef state; unGHCi g ref
 
 instance Monad GHCi where
-  (GHCi m) >>= k  =  GHCi $ \s -> m s >>= \(s,a) -> unGHCi (k a) s
-  return a  = GHCi $ \s -> return (s,a)
+  (GHCi m) >>= k  =  GHCi $ \s -> m s >>= \a -> unGHCi (k a) s
+  return a  = GHCi $ \s -> return a
 
-getGHCiState   = GHCi $ \s -> return (s,s)
-setGHCiState s = GHCi $ \_ -> return (s,())
+getGHCiState   = GHCi $ \r -> readIORef r
+setGHCiState s = GHCi $ \r -> writeIORef r s
 
 isOptionSet :: GHCiOption -> GHCi Bool
 isOptionSet opt
@@ -619,7 +711,8 @@ unsetOption opt
  = do st <- getGHCiState
       setGHCiState (st{ options = filter (/= opt) (options st) })
 
-io m = GHCi $ \s -> m >>= \a -> return (s,a)
+io :: IO a -> GHCi a
+io m = GHCi { unGHCi = \s -> m >>= return }
 
 -----------------------------------------------------------------------------
 -- recursive exception handlers
@@ -644,7 +737,11 @@ ghciUnblock (GHCi a) = GHCi $ \s -> Exception.unblock (a s)
 --        e.g.    On unix     "qt"  denotes "libqt.so"
 --                On WinDoze  "burble"  denotes "burble.DLL"
 --        addDLL is platform-specific and adds the lib/.so/.DLL
---        prefixes plaform-dependently; we don't do that here.
+--        suffixes platform-dependently; we don't do that here.
+-- 
+-- For dynamic objects only, try to find the object file in all the 
+-- directories specified in v_Library_Paths before giving up.
+
 type LibrarySpec
    = Either FilePath String
 
@@ -654,30 +751,64 @@ showLS (Right nm) = "(dynamic) " ++ nm
 linkPackages :: [LibrarySpec] -> [PackageConfig] -> IO ()
 linkPackages cmdline_lib_specs pkgs
    = do sequence_ [ linkPackage (name p `elem` loaded) p | p <- reverse pkgs ]
-        mapM_ preloadLib cmdline_lib_specs
+        lib_paths <- readIORef v_Library_paths
+        mapM_ (preloadLib lib_paths) cmdline_lib_specs
+	if (null cmdline_lib_specs)
+	   then return ()
+	   else do putStr "final link ... "
+		   ok <- resolveObjs
+		   if ok then putStrLn "done."
+	      		 else throwDyn (InstallationError "linking extra libraries/objects failed")
      where
-	-- packages that are already linked into GHCi
-	loaded = [ "concurrent", "posix", "text", "util" ]
-
-        preloadLib lib_spec
+	-- Packages that are already linked into GHCi.  For mingw32, we only
+	-- skip gmp and rts, since std and after need to load the msvcrt.dll
+	-- library which std depends on.
+	loaded 
+#          ifndef mingw32_TARGET_OS
+           = [ "gmp", "rts", "std", "concurrent", "posix", "text", "util" ]
+#          else
+           = [ "gmp", "rts" ]
+#          endif
+
+        preloadLib :: [String] -> LibrarySpec -> IO ()
+        preloadLib lib_paths lib_spec
            = do putStr ("Loading object " ++ showLS lib_spec ++ " ... ")
                 case lib_spec of
                    Left static_ish
-                      -> do b <- doesFileExist static_ish
-                            if    not b
-                             then do putStr "not found.\n"
-                                     croak
-                             else do loadObj static_ish
-                                     putStr "done.\n"
+                      -> do b <- preload_static lib_paths static_ish
+                            putStrLn (if b then "done." else "not found")
                    Right dll_unadorned
-                      -> do maybe_errmsg <- addDLL dll_unadorned
-                            if    maybe_errmsg == nullPtr
-                             then putStr "done.\n"
-                             else do str <- peekCString maybe_errmsg
-                                     putStr ("failed (" ++ str ++ ")\n")
-                                     croak
-
-        croak = throwDyn (CmdLineError "user specified .o/.so/.DLL could not be loaded.")
+                      -> -- We add "" to the set of paths to try, so that
+                         -- if none of the real paths match, we force addDLL
+                         -- to look in the default dynamic-link search paths.
+                         do b <- preload_dynamic (lib_paths++[""]) dll_unadorned
+                            when (not b) (cantFind lib_paths lib_spec)
+                            putStrLn "done"
+
+        cantFind :: [String] -> LibrarySpec -> IO ()
+        cantFind paths spec
+           = do putStr ("failed.\nCan't find " ++ showLS spec
+                        ++ " in directories:\n"
+                        ++ unlines (map ("   "++) paths) )
+                give_up
+
+        -- not interested in the paths in the static case.
+        preload_static paths name
+           = do b <- doesFileExist name
+                if not b then return False
+                         else loadObj name >> return True
+
+        preload_dynamic [] name
+           = return False
+        preload_dynamic (path:paths) rootname
+           = do maybe_errmsg <- addDLL path rootname
+                if    maybe_errmsg /= nullPtr
+                 then preload_dynamic paths rootname
+                 else return True
+
+        give_up 
+           = (throwDyn . CmdLineError)
+                "user specified .o/.so/.DLL could not be loaded."
 
 
 linkPackage :: Bool -> PackageConfig -> IO ()
@@ -701,8 +832,9 @@ linkPackage loaded_in_ghci pkg
 
         mapM loadClassified sos_first
         putStr "linking ... "
-        resolveObjs
-        putStrLn "done."
+        ok <- resolveObjs
+	if ok then putStrLn "done."
+	      else panic ("can't load package `" ++ name pkg ++ "'")
      where
         isRight (Right _) = True
         isRight (Left _)  = False
@@ -711,11 +843,11 @@ loadClassified :: LibrarySpec -> IO ()
 loadClassified (Left obj_absolute_filename)
    = do loadObj obj_absolute_filename
 loadClassified (Right dll_unadorned)
-   = do maybe_errmsg <- addDLL dll_unadorned
+   = do maybe_errmsg <- addDLL "" dll_unadorned -- doesn't seem right to me
         if    maybe_errmsg == nullPtr
          then return ()
          else do str <- peekCString maybe_errmsg
-                 throwDyn (CmdLineError ("can't find .o or .so/.DLL for: " 
+                 throwDyn (CmdLineError ("can't load .so/.DLL for: " 
                                        ++ dll_unadorned ++ " (" ++ str ++ ")" ))
 
 locateOneObj :: [FilePath] -> String -> IO LibrarySpec