X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Fghci%2FInteractiveUI.hs;h=bc0b3bc0923d261d26d65266176a671f09030694;hp=573aaa01cc49fb4a75746534d2f81e0b7d80133a;hb=940524aec90652b5ef81789c9a453c57c0e42cc9;hpb=d0a4736028a4834f6ce643a0629c7b5f1f451d34

diff --git a/compiler/ghci/InteractiveUI.hs b/compiler/ghci/InteractiveUI.hs
index 573aaa0..bc0b3bc 100644
--- a/compiler/ghci/InteractiveUI.hs
+++ b/compiler/ghci/InteractiveUI.hs
@@ -14,22 +14,21 @@ module InteractiveUI (
 #include "HsVersions.h"
 
 import GhciMonad
+import GhciTags
+import Debugger
 
 -- The GHC interface
 import qualified GHC
 import GHC              ( Session, LoadHowMuch(..), Target(..),  TargetId(..),
-                          Type, Module, ModuleName, TyThing(..), Phase )
+                          Type, Module, ModuleName, TyThing(..), Phase,
+                          BreakIndex, Name, SrcSpan, Resume, SingleStep )
 import DynFlags
 import Packages
 import PackageConfig
 import UniqFM
 import PprTyThing
-import Outputable
-
--- for createtags
-import Name
-import OccName
-import SrcLoc
+import Outputable       hiding (printForUser)
+import Module           -- for ModuleEnv
 
 -- Other random utilities
 import Digraph
@@ -39,19 +38,7 @@ import Config
 import StaticFlags
 import Linker
 import Util
-
--- The debugger
-import Breakpoints
-import Debugger hiding  ( addModule )
-import HscTypes
-import Id
-import Var       ( globaliseId )
-import IdInfo
-import NameEnv
-import RdrName
-import Module
-import Type
-import TcType
+import FastString
 
 #ifndef mingw32_HOST_OS
 import System.Posix
@@ -74,10 +61,9 @@ import System.Console.Readline as Readline
 import Control.Exception as Exception
 -- import Control.Concurrent
 
-import Numeric
+import qualified Data.ByteString.Char8 as BS
 import Data.List
-import Data.Int		( Int64 )
-import Data.Maybe	( isJust, isNothing, fromMaybe, catMaybes )
+import Data.Maybe
 import System.Cmd
 import System.Environment
 import System.Exit	( exitWith, ExitCode(..) )
@@ -86,13 +72,15 @@ import System.IO
 import System.IO.Error as IO
 import Data.Char
 import Data.Dynamic
+import Data.Array
 import Control.Monad as Monad
-import Foreign.StablePtr	( newStablePtr )
+import Text.Printf
 
+import Foreign.StablePtr	( newStablePtr )
 import GHC.Exts		( unsafeCoerce# )
 import GHC.IOBase	( IOErrorType(InvalidArgument) )
 
-import Data.IORef	( IORef, newIORef, readIORef, writeIORef )
+import Data.IORef	( IORef, readIORef, writeIORef )
 
 import System.Posix.Internals ( setNonBlockingFD )
 
@@ -101,9 +89,9 @@ import System.Posix.Internals ( setNonBlockingFD )
 ghciWelcomeMsg =
  "   ___         ___ _\n"++
  "  / _ \\ /\\  /\\/ __(_)\n"++
- " / /_\\// /_/ / /  | |      GHC Interactive, version " ++ cProjectVersion ++ ", for Haskell 98.\n"++
- "/ /_\\\\/ __  / /___| |      http://www.haskell.org/ghc/\n"++
- "\\____/\\/ /_/\\____/|_|      Type :? for help.\n"
+ " / /_\\// /_/ / /  | |    GHC Interactive, version " ++ cProjectVersion ++ ", for Haskell 98.\n"++
+ "/ /_\\\\/ __  / /___| |    http://www.haskell.org/ghc/\n"++
+ "\\____/\\/ /_/\\____/|_|    Type :? for help.\n"
 
 type Command = (String, String -> GHCi Bool, Bool, String -> IO [String])
 cmdName (n,_,_,_) = n
@@ -112,100 +100,108 @@ GLOBAL_VAR(commands, builtin_commands, [Command])
 
 builtin_commands :: [Command]
 builtin_commands = [
-  ("add",	tlC$ keepGoingPaths addModule,	False, completeFilename),
+	-- Hugs users are accustomed to :e, so make sure it doesn't overlap
+  ("?",		keepGoing help,			False, completeNone),
+  ("add",	keepGoingPaths addModule,	False, completeFilename),
+  ("abandon",   keepGoing abandonCmd,           False, completeNone),
+  ("break",     keepGoing breakCmd,             False, completeIdentifier),
+  ("back",      keepGoing backCmd,              False, completeNone),
   ("browse",    keepGoing browseCmd,		False, completeModule),
-#ifdef DEBUGGER
-        -- I think that :c should mean :continue rather than :cd, makes more sense
-        --  (pepe 01.11.07)
-  ("continue",  const(bkptOptions "continue"),  False, completeNone),
-#endif
-  ("cd",    	tlC$ keepGoing changeDirectory,	False, completeFilename),
+  ("cd",    	keepGoing changeDirectory,	False, completeFilename),
+  ("check",	keepGoing checkModule,		False, completeHomeModule),
+  ("continue",  keepGoing continueCmd,          False, completeNone),
+  ("ctags",	keepGoing createCTagsFileCmd, 	False, completeFilename),
   ("def",	keepGoing defineMacro,		False, completeIdentifier),
+  ("delete",    keepGoing deleteCmd,            False, completeNone),
   ("e", 	keepGoing editFile,		False, completeFilename),
-	-- Hugs users are accustomed to :e, so make sure it doesn't overlap
   ("edit",	keepGoing editFile,		False, completeFilename),
+  ("etags",	keepGoing createETagsFileCmd,	False, completeFilename),
+  ("force",     keepGoing forceCmd,             False, completeIdentifier),
+  ("forward",   keepGoing forwardCmd,           False, completeNone),
   ("help",	keepGoing help,			False, completeNone),
-  ("?",		keepGoing help,			False, completeNone),
+  ("history",   keepGoing historyCmd,           False, completeNone), 
   ("info",      keepGoing info,			False, completeIdentifier),
-  ("load",	tlC$ keepGoingPaths loadModule_,False, completeHomeModuleOrFile),
+  ("kind",	keepGoing kindOfType,		False, completeIdentifier),
+  ("load",	keepGoingPaths loadModule_,     False, completeHomeModuleOrFile),
+  ("list",	keepGoing listCmd,              False, completeNone),
   ("module",	keepGoing setContext,		False, completeModule),
-  ("main",	tlC$ keepGoing runMain,		False, completeIdentifier),
-  ("reload", 	tlC$ keepGoing reloadModule,  	False, completeNone),
-  ("check",	keepGoing checkModule,		False, completeHomeModule),
+  ("main",	keepGoing runMain,		False, completeIdentifier),
+  ("print",     keepGoing printCmd,             False, completeIdentifier),
+  ("quit",	quit,				False, completeNone),
+  ("reload", 	keepGoing reloadModule,  	False, completeNone),
   ("set",	keepGoing setCmd,		True,  completeSetOptions),
   ("show",	keepGoing showCmd,		False, completeNone),
-  ("etags",	keepGoing createETagsFileCmd,	False, completeFilename),
-  ("ctags",	keepGoing createCTagsFileCmd, 	False, completeFilename),
+  ("sprint",    keepGoing sprintCmd,            False, completeIdentifier),
+  ("step",      keepGoing stepCmd,              False, completeIdentifier), 
   ("type",	keepGoing typeOfExpr,		False, completeIdentifier),
-#if defined(DEBUGGER)
-  ("print",     keepGoing (pprintClosureCommand True False), False, completeIdentifier),
-  ("sprint",    keepGoing (pprintClosureCommand False False),False, completeIdentifier),
-  ("force",     keepGoing (pprintClosureCommand False True), False, completeIdentifier),
-  ("breakpoint",bkptOptions,                    False, completeBkpt),
-#endif
-  ("kind",	keepGoing kindOfType,		False, completeIdentifier),
-  ("unset",	keepGoing unsetOptions,		True,  completeSetOptions),
+  ("trace",     keepGoing traceCmd,             False, completeIdentifier), 
   ("undef",     keepGoing undefineMacro,	False, completeMacro),
-  ("quit",	quit,				False, completeNone)
+  ("unset",	keepGoing unsetOptions,		True,  completeSetOptions)
   ]
 
 keepGoing :: (String -> GHCi ()) -> (String -> GHCi Bool)
 keepGoing a str = a str >> return False
 
--- tlC: Top Level Command, not allowed in inferior sessions
-tlC ::  (String -> GHCi Bool) -> (String -> GHCi Bool)
-tlC a str = do 
-    top_level <- isTopLevel
-    if not top_level
-       then throwDyn (CmdLineError "Command only allowed at Top Level")
-       else a str
-
 keepGoingPaths :: ([FilePath] -> GHCi ()) -> (String -> GHCi Bool)
 keepGoingPaths a str = a (toArgs str) >> return False
 
 shortHelpText = "use :? for help.\n"
 
--- NOTE: spaces at the end of each line to workaround CPP/string gap bug.
 helpText =
  " Commands available from the prompt:\n" ++
  "\n" ++
- "   <stmt>                      evaluate/run <stmt>\n" ++
+ "   <statement>                 evaluate/run <statement>\n" ++
  "   :add <filename> ...         add module(s) to the current target set\n" ++
- "   :breakpoint <option>        commands for the GHCi debugger\n" ++
  "   :browse [*]<module>         display the names defined by <module>\n" ++
  "   :cd <dir>                   change directory to <dir>\n" ++
- "   :continue                   equivalent to ':breakpoint continue'\n"  ++
+ "   :ctags [<file>]             create tags file for Vi (default: \"tags\")\n" ++
  "   :def <cmd> <expr>           define a command :<cmd>\n" ++
  "   :edit <file>                edit file\n" ++
  "   :edit                       edit last module\n" ++
+ "   :etags [<file>]             create tags file for Emacs (default: \"TAGS\")\n" ++
  "   :help, :?                   display this list of commands\n" ++
  "   :info [<name> ...]          display information about the given names\n" ++
- "   :print [<name> ...]         prints a value without forcing its computation\n" ++
- "   :sprint [<name> ...]        simplified version of :print\n" ++
+ "   :kind <type>                show the kind of <type>\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" ++
+ "   :quit                       exit GHCi\n" ++
  "   :reload                     reload the current module set\n" ++
+ "   :type <expr>                show the type of <expr>\n" ++
+ "   :undef <cmd>                undefine user-defined command :<cmd>\n" ++
+ "   :!<command>                 run the shell command <command>\n" ++
+ "\n" ++
+ " -- Commands for debugging:\n" ++
+ "\n" ++
+ "   :abandon                    at a breakpoint, abandon current computation\n" ++
+ "   :back                       go back in the history (after :trace)\n" ++
+ "   :break [<mod>] <l> [<col>]  set a breakpoint at the specified location\n" ++
+ "   :break <name>               set a breakpoint on the specified function\n" ++
+ "   :continue                   resume after a breakpoint\n" ++
+ "   :delete <number>            delete the specified breakpoint\n" ++
+ "   :delete *                   delete all breakpoints\n" ++
+ "   :force <expr>               print <expr>, forcing unevaluated parts\n" ++
+ "   :forward                    go forward in the history (after :back)\n" ++
+ "   :history [<n>]              show the last <n> items in the history (after :trace)\n" ++
+ "   :print [<name> ...]         prints a value without forcing its computation\n" ++
+ "   :step                       single-step after stopping at a breakpoint\n"++
+ "   :step <expr>                single-step into <expr>\n"++
+ "   :trace                      trace after stopping at a breakpoint\n"++
+ "   :trace <expr>               trace into <expr> (remembers breakpoints for :history)\n"++
+ "   :sprint [<name> ...]        simplifed version of :print\n" ++
+
+ "\n" ++
+ " -- Commands for changing settings:\n" ++
  "\n" ++
  "   :set <option> ...           set options\n" ++
  "   :set args <arg> ...         set the arguments returned by System.getArgs\n" ++
  "   :set prog <progname>        set the value returned by System.getProgName\n" ++
  "   :set prompt <prompt>        set the prompt used in GHCi\n" ++
  "   :set editor <cmd>           set the command used for :edit\n" ++
- "\n" ++
- "   :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 (default: \"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" ++
+ "   :set stop <cmd>             set the command to run when a breakpoint is hit\n" ++
  "   :unset <option> ...         unset options\n" ++
- "   :quit                       exit GHCi\n" ++
- "   :!<command>                 run the shell command <command>\n" ++
  "\n" ++
- " Options for ':set' and ':unset':\n" ++
+ "  Options for ':set' and ':unset':\n" ++
  "\n" ++
  "    +r            revert top-level expressions after each evaluation\n" ++
  "    +s            print timing/memory stats after each evaluation\n" ++
@@ -213,13 +209,14 @@ helpText =
  "    -<flags>      most GHC command line flags can also be set here\n" ++
  "                         (eg. -v2, -fglasgow-exts, etc.)\n" ++
  "\n" ++
- " Options for ':breakpoint':\n" ++
- "   list                                     list the current breakpoints\n" ++
- "   add Module line [col]                    add a new breakpoint\n" ++
- "   del (breakpoint# | Module line [col])    delete a breakpoint\n" ++
- "   continue                                 continue execution\n"  ++
- "   stop                   Stop a computation and return to the top level\n" ++
- "   step [count]           Step by step execution (DISABLED)\n"
+ " -- Commands for displaying information:\n" ++
+ "\n" ++
+ "   :show bindings              show the current bindings made at the prompt\n" ++
+ "   :show breaks                show the active breakpoints\n" ++
+ "   :show context               show the breakpoint context\n" ++
+ "   :show modules               show the currently loaded modules\n" ++
+ "   :show <setting>             show anything that can be set with :set (e.g. args)\n" ++
+ "\n" 
 
 findEditor = do
   getEnv "EDITOR" 
@@ -260,7 +257,7 @@ interactiveUI session srcs maybe_expr = do
 	hSetBuffering stdin NoBuffering
 
 	-- initial context is just the Prelude
-   prel_mod <- GHC.findModule session prel_name Nothing
+   prel_mod <- GHC.findModule session prel_name (Just basePackageId)
    GHC.setContext session [] [prel_mod]
 
 #ifdef USE_READLINE
@@ -277,20 +274,20 @@ interactiveUI session srcs maybe_expr = do
    Readline.setCompleterWordBreakCharacters word_break_chars
 #endif
 
-   bkptTable <- newIORef emptyBkptTable
-   GHC.setBreakpointHandler session (instrumentationBkptHandler bkptTable)
    default_editor <- findEditor
 
    startGHCi (runGHCi srcs maybe_expr)
 	GHCiState{ progname = "<interactive>",
 		   args = [],
                    prompt = "%s> ",
+                   stop = "",
 		   editor = default_editor,
 		   session = session,
 		   options = [],
                    prelude = prel_mod,
-                   bkptTable = bkptTable,
-		   topLevel  = True
+                   break_ctr = 0,
+                   breaks = [],
+                   tickarrays = emptyModuleEnv
                  }
 
 #ifdef USE_READLINE
@@ -433,10 +430,9 @@ checkPerms name =
 
 fileLoop :: Handle -> Bool -> GHCi ()
 fileLoop hdl show_prompt = do
-   session <- getSession
-   (mod,imports) <- io (GHC.getContext session)
-   st <- getGHCiState
-   when show_prompt (io (putStr (mkPrompt mod imports (prompt st))))
+   when show_prompt $ do
+        prompt <- mkPrompt
+        (io (putStr prompt))
    l <- io (IO.try (hGetLine hdl))
    case l of
 	Left e | isEOFError e		   -> return ()
@@ -461,17 +457,41 @@ stringLoop (s:ss) = do
 	l  -> do quit <- runCommand l
                  if quit then return True else stringLoop ss
 
-mkPrompt toplevs exports prompt
-  = showSDoc $ f prompt
-    where
-        f ('%':'s':xs) = perc_s <> f xs
+mkPrompt = do
+  session <- getSession
+  (toplevs,exports) <- io (GHC.getContext session)
+  resumes <- io $ GHC.getResumeContext session
+
+  context_bit <-
+        case resumes of
+            [] -> return empty
+            r:rs -> do
+                let ix = GHC.resumeHistoryIx r
+                if ix == 0
+                   then return (brackets (ppr (GHC.resumeSpan r)) <> space)
+                   else do
+                        let hist = GHC.resumeHistory r !! (ix-1)
+                        span <- io $ GHC.getHistorySpan session hist
+                        return (brackets (ppr (negate ix) <> char ':' 
+                                          <+> ppr span) <> space)
+  let
+        dots | r:rs <- resumes, not (null rs) = text "... "
+             | otherwise = empty
+
+        modules_bit = 
+             hsep (map (\m -> char '*' <> ppr (GHC.moduleName m)) toplevs) <+>
+             hsep (map (ppr . GHC.moduleName) exports)
+
+        deflt_prompt = dots <> context_bit <> modules_bit
+
+        f ('%':'s':xs) = deflt_prompt <> f xs
         f ('%':'%':xs) = char '%' <> f xs
         f (x:xs) = char x <> f xs
         f [] = empty
-    
-        perc_s = hsep (map (\m -> char '*' <> ppr (GHC.moduleName m)) toplevs) <+>
-                 hsep (map (ppr . GHC.moduleName) exports)
-             
+   --
+  st <- getGHCiState
+  return (showSDoc (f (prompt st)))
+
 
 #ifdef USE_READLINE
 readlineLoop :: GHCi ()
@@ -481,8 +501,9 @@ readlineLoop = do
    io yield
    saveSession -- for use by completion
    st <- getGHCiState
-   l <- io (readline (mkPrompt mod imports (prompt st))
-	  	`finally` setNonBlockingFD 0)
+   mb_span <- getCurrentBreakSpan
+   prompt <- mkPrompt
+   l <- io (readline prompt `finally` setNonBlockingFD 0)
 		-- readline sometimes puts stdin into blocking mode,
 		-- so we need to put it back for the IO library
    splatSavedSession
@@ -502,7 +523,7 @@ runCommand c = ghciHandle handler (doCommand c)
   where 
     doCommand (':' : command) = specialCommand command
     doCommand stmt
-       = do timeIt (do nms <- runStmt stmt; finishEvalExpr nms)
+       = do timeIt $ runStmt stmt GHC.RunToCompletion
             return False
 
 -- This version is for the GHC command-line option -e.  The only difference
@@ -516,38 +537,50 @@ runCommandEval c = ghciHandle handleEval (doCommand c)
 
     doCommand (':' : command) = specialCommand command
     doCommand stmt
-       = do nms <- runStmt stmt
-	    case nms of 
-		Nothing -> io (exitWith (ExitFailure 1))
+       = do r <- runStmt stmt GHC.RunToCompletion
+	    case r of 
+		False -> io (exitWith (ExitFailure 1))
 		  -- failure to run the command causes exit(1) for ghc -e.
-		_       -> finishEvalExpr nms
+		_       -> return True
 
-runStmt :: String -> GHCi (Maybe [Name])
-runStmt stmt
- | null (filter (not.isSpace) stmt) = return (Just [])
+runStmt :: String -> SingleStep -> GHCi Bool
+runStmt stmt step
+ | null (filter (not.isSpace) stmt) = return False
  | otherwise
  = do st <- getGHCiState
       session <- getSession
       result <- io $ withProgName (progname st) $ withArgs (args st) $
-	     	     GHC.runStmt session stmt
-      case result of
-	GHC.RunFailed      -> return Nothing
-	GHC.RunException e -> throw e  -- this is caught by runCommand(Eval)
-	GHC.RunOk names    -> return (Just names)
-
--- possibly print the type and revert CAFs after evaluating an expression
-finishEvalExpr mb_names
- = do b <- isOptionSet ShowType
-      session <- getSession
-      case mb_names of
-	Nothing    -> return ()      
-	Just names -> when b (mapM_ (showTypeOfName session) names)
+	     	     GHC.runStmt session stmt step
+      afterRunStmt result
+
+
+afterRunStmt :: GHC.RunResult -> GHCi Bool
+                                 -- False <=> the statement failed to compile
+afterRunStmt (GHC.RunException e) = throw e
+afterRunStmt run_result = do
+  session <- getSession
+  case run_result of
+     GHC.RunOk names -> do
+        show_types <- isOptionSet ShowType
+        when show_types $ mapM_ (showTypeOfName session) names
+     GHC.RunBreak _ names _ -> do
+        resumes <- io $ GHC.getResumeContext session
+        printForUser $ ptext SLIT("Stopped at") <+> 
+                       ppr (GHC.resumeSpan (head resumes))
+        mapM_ (showTypeOfName session) names
+        -- run the command set with ":set stop <cmd>"
+        st <- getGHCiState
+        runCommand (stop st)
+        return ()
+     _ -> return ()
+
+  flushInterpBuffers
+  io installSignalHandlers
+  b <- isOptionSet RevertCAFs
+  io (when b revertCAFs)
+
+  return (case run_result of GHC.RunOk _ -> True; _ -> False)
 
-      flushInterpBuffers
-      io installSignalHandlers
-      b <- isOptionSet RevertCAFs
-      io (when b revertCAFs)
-      return True
 
 showTypeOfName :: Session -> Name -> GHCi ()
 showTypeOfName session n
@@ -576,9 +609,29 @@ lookupCommand str = do
      		[] -> return Nothing
      		c:_ -> return (Just c)
 
+
+getCurrentBreakSpan :: GHCi (Maybe SrcSpan)
+getCurrentBreakSpan = do
+  session <- getSession
+  resumes <- io $ GHC.getResumeContext session
+  case resumes of
+    [] -> return Nothing
+    (r:rs) -> do
+        let ix = GHC.resumeHistoryIx r
+        if ix == 0
+           then return (Just (GHC.resumeSpan r))
+           else do
+                let hist = GHC.resumeHistory r !! (ix-1)
+                span <- io $ GHC.getHistorySpan session hist
+                return (Just span)
+
 -----------------------------------------------------------------------------
 -- Commands
 
+noArgs :: GHCi () -> String -> GHCi ()
+noArgs m "" = m
+noArgs m _ = io $ putStrLn "This command takes no arguments"
+
 help :: String -> GHCi ()
 help _ = io (putStr helpText)
 
@@ -618,9 +671,6 @@ pprInfo exts (thing, fixity, insts)
 	| 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))
@@ -725,6 +775,7 @@ loadModule' files = do
   session <- getSession
 
   -- unload first
+  discardActiveBreakPoints
   io (GHC.setTargets session [])
   io (GHC.load session LoadAllTargets)
 
@@ -740,9 +791,7 @@ loadModule' files = do
   -- as a ToDo for now.
 
   io (GHC.setTargets session targets)
-  ok <- io (GHC.load session LoadAllTargets)
-  afterLoad ok session
-  return ok
+  doLoad session LoadAllTargets
 
 checkModule :: String -> GHCi ()
 checkModule m = do
@@ -765,24 +814,31 @@ checkModule m = do
 reloadModule :: String -> GHCi ()
 reloadModule "" = do
   io (revertCAFs)		-- always revert CAFs on reload.
+  discardActiveBreakPoints
   session <- getSession
-  ok <- io (GHC.load session LoadAllTargets)
-  afterLoad ok session
+  doLoad session LoadAllTargets
+  return ()
 reloadModule m = do
   io (revertCAFs)		-- always revert CAFs on reload.
+  discardActiveBreakPoints
   session <- getSession
-  ok <- io (GHC.load session (LoadUpTo (GHC.mkModuleName m)))
+  doLoad session (LoadUpTo (GHC.mkModuleName m))
+  return ()
+
+doLoad session howmuch = do
+  -- turn off breakpoints before we load: we can't turn them off later, because
+  -- the ModBreaks will have gone away.
+  discardActiveBreakPoints
+  ok <- io (GHC.load session howmuch)
   afterLoad ok session
+  return ok
 
 afterLoad ok session = do
   io (revertCAFs)  -- always revert CAFs on load.
+  discardTickArrays
   graph <- io (GHC.getModuleGraph session)
   graph' <- filterM (io . GHC.isLoaded session . GHC.ms_mod_name) graph
   setContextAfterLoad session graph'
-  do 
-     bt  <- getBkptTable
-     bt' <- io$ refreshBkptTable session bt graph'
-     setBkptTable bt'
   modulesLoadedMsg ok (map GHC.ms_mod_name graph')
 
 setContextAfterLoad session [] = do
@@ -840,8 +896,7 @@ typeOfExpr str
        case maybe_ty of
 	  Nothing -> return ()
 	  Just ty -> do ty' <- cleanType ty
-			tystr <- showForUser (ppr ty')
-		        io (putStrLn (str ++ " :: " ++ tystr))
+                        printForUser $ text str <> text " :: " <> ppr ty'
 
 kindOfType :: String -> GHCi ()
 kindOfType str 
@@ -849,132 +904,15 @@ kindOfType str
        maybe_ty <- io (GHC.typeKind cms str)
        case maybe_ty of
 	  Nothing    -> return ()
-	  Just ty    -> do tystr <- showForUser (ppr ty)
-		           io (putStrLn (str ++ " :: " ++ tystr))
-
-quit :: String -> GHCi Bool
-quit _ =  do in_inferior_session <- liftM not isTopLevel 
-             if in_inferior_session 
-               then throwDyn StopParentSession
-               else return True
+	  Just ty    -> printForUser $ text str <> text " :: " <> ppr ty
           
+quit :: String -> GHCi Bool
+quit _ = return True
 
 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 '" 
-                                ++ GHC.moduleNameString (GHC.moduleName 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 ()
@@ -986,10 +924,8 @@ browseCmd m =
 
 browseModule m exports_only = do
   s <- getSession
-  modl <- io $ GHC.findModule s (GHC.mkModuleName m) Nothing
-  is_interpreted <- io (GHC.moduleIsInterpreted s modl)
-  when (not is_interpreted && not exports_only) $
-	throwDyn (CmdLineError ("module '" ++ m ++ "' is not interpreted"))
+  modl <- if exports_only then lookupModule m
+                          else wantInterpretedModule m
 
   -- Temporarily set the context to the module we're interested in,
   -- just so we can get an appropriate PrintUnqualified
@@ -1110,6 +1046,7 @@ setCmd str
 	("prog":prog) -> setProg prog
         ("prompt":prompt) -> setPrompt (after 6)
         ("editor":cmd) -> setEditor (after 6)
+        ("stop":cmd) -> setStop (after 4)
 	wds -> setOptions wds
    where after n = dropWhile isSpace $ drop n $ dropWhile isSpace str
 
@@ -1127,6 +1064,10 @@ setEditor cmd = do
   st <- getGHCiState
   setGHCiState st{ editor = cmd }
 
+setStop cmd = do
+  st <- getGHCiState
+  setGHCiState st{ stop = cmd }
+
 setPrompt value = do
   st <- getGHCiState
   if null value
@@ -1140,8 +1081,10 @@ setOptions wds =
    do -- first, deal with the GHCi opts (+s, +t, etc.)
       let (plus_opts, minus_opts)  = partition isPlus wds
       mapM_ setOpt plus_opts
-
       -- then, dynamic flags
+      newDynFlags minus_opts
+
+newDynFlags minus_opts = do
       dflags <- getDynFlags
       let pkg_flags = packageFlags dflags
       (dflags',leftovers) <- io $ GHC.parseDynamicFlags dflags minus_opts
@@ -1179,10 +1122,11 @@ unsetOptions str
 
        mapM_ unsetOpt plus_opts
  
-       -- can't do GHC flags for now
-       if (not (null minus_opts))
-	  then throwDyn (CmdLineError "can't unset GHC command-line flags")
-	  else return ()
+       let no_flag ('-':'f':rest) = return ("-fno-" ++ rest)
+           no_flag f = throwDyn (ProgramError ("don't know how to reverse " ++ f))
+
+       no_flags <- mapM no_flag minus_opts
+       newDynFlags no_flags
 
 isMinus ('-':s) = True
 isMinus _ = False
@@ -1214,13 +1158,20 @@ optToStr RevertCAFs = "r"
 -- ---------------------------------------------------------------------------
 -- code for `:show'
 
-showCmd str =
+showCmd str = do
+  st <- getGHCiState
   case words str of
+        ["args"]     -> io $ putStrLn (show (args st))
+        ["prog"]     -> io $ putStrLn (show (progname st))
+        ["prompt"]   -> io $ putStrLn (show (prompt st))
+        ["editor"]   -> io $ putStrLn (show (editor st))
+        ["stop"]     -> io $ putStrLn (show (stop st))
 	["modules" ] -> showModules
 	["bindings"] -> showBindings
 	["linker"]   -> io showLinkerState
-        ["breakpoints"] -> showBkptTable
-	_ -> throwDyn (CmdLineError "syntax:  :show [modules|bindings]")
+        ["breaks"]   -> showBkptTable
+        ["context"]  -> showContext
+	_ -> throwDyn (CmdLineError "syntax:  :show [args|prog|prompt|editor|stop|modules|bindings|breaks|context]")
 
 showModules = do
   session <- getSession
@@ -1238,8 +1189,7 @@ showBindings = do
 
 showTyThing (AnId id) = do 
   ty' <- cleanType (GHC.idType id)
-  str <- showForUser (ppr id <> text " :: " <> ppr ty')
-  io (putStrLn str)
+  printForUser $ ppr id <> text " :: " <> ppr ty'
 showTyThing _  = return ()
 
 -- if -fglasgow-exts is on we show the foralls, otherwise we don't.
@@ -1252,12 +1202,20 @@ cleanType ty = do
 
 showBkptTable :: GHCi ()
 showBkptTable = do
-  bt     <- getBkptTable
-  msg <- showForUser . vcat $ 
-             [ ppr mod <> colon <+> fcat 
-                       [ parens(int row <> comma <> int col) | (row,col) <- sites]
-               | (mod, sites) <-  sitesList bt ]
-  io (putStrLn msg)
+  st <- getGHCiState
+  printForUser $ prettyLocations (breaks st)
+
+showContext :: GHCi ()
+showContext = do
+   session <- getSession
+   resumes <- io $ GHC.getResumeContext session
+   printForUser $ vcat (map pp_resume (reverse resumes))
+  where
+   pp_resume resume =
+        ptext SLIT("--> ") <> text (GHC.resumeStmt resume)
+        $$ nest 2 (ptext SLIT("Stopped at") <+> ppr (GHC.resumeSpan resume))
+
+
 -- -----------------------------------------------------------------------------
 -- Completion
 
@@ -1329,12 +1287,6 @@ completeSetOptions w = do
   return (filter (w `isPrefixOf`) options)
     where options = "args":"prog":allFlags
 
-completeBkpt = unionComplete completeModule completeBkptCmds
-
-completeBkptCmds w = do
-  return (filter (w `isPrefixOf`) options)
-    where options = ["add","del","list","stop"]
-
 completeFilename = Readline.filenameCompletionFunction
 
 completeHomeModuleOrFile = unionComplete completeHomeModule completeFilename
@@ -1395,18 +1347,6 @@ completeBkpt       = completeNone
 -- handler arond the flushing operation, so if stderr is closed
 -- GHCi will just die gracefully rather than going into an infinite loop.
 handler :: Exception -> GHCi Bool
-handler (DynException dyn) 
-  | Just StopChildSession <- fromDynamic dyn 
-     -- propagate to the parent session
-  = do ASSERTM (liftM not isTopLevel) 
-       throwDyn StopChildSession
-
-  | Just StopParentSession <- fromDynamic dyn 
-  = do at_topLevel <-  isTopLevel
-       if at_topLevel then return True else throwDyn StopParentSession
-  
-  | Just (ChildSessionStopped msg) <- fromDynamic dyn     
-  = io(putStrLn msg) >> return False
 
 handler exception = do
   flushInterpBuffers
@@ -1452,6 +1392,28 @@ expandPath path =
    other -> 
 	return other
 
+wantInterpretedModule :: String -> GHCi Module
+wantInterpretedModule str = do
+   session <- getSession
+   modl <- lookupModule str
+   is_interpreted <- io (GHC.moduleIsInterpreted session modl)
+   when (not is_interpreted) $
+       throwDyn (CmdLineError ("module '" ++ str ++ "' is not interpreted"))
+   return modl
+
+wantNameFromInterpretedModule noCanDo str and_then = do
+   session <- getSession
+   names <- io $ GHC.parseName session str
+   case names of
+      []    -> return ()
+      (n:_) -> do
+            let modl = GHC.nameModule n
+            is_interpreted <- io (GHC.moduleIsInterpreted session modl)
+            if not is_interpreted
+               then noCanDo n $ text "module " <> ppr modl <>
+                                text " is not interpreted"
+               else and_then n
+
 -- ----------------------------------------------------------------------------
 -- Windows console setup
 
@@ -1476,84 +1438,390 @@ setUpConsole = do
 #endif
 	return ()
 
+-- -----------------------------------------------------------------------------
+-- commands for debugger
+
+sprintCmd = pprintCommand False False
+printCmd  = pprintCommand True False
+forceCmd  = pprintCommand False True
+
+pprintCommand bind force str = do
+  session <- getSession
+  io $ pprintClosureCommand session bind force str
 
-instrumentationBkptHandler :: IORef (BkptTable Module) -> BkptHandler Module
-instrumentationBkptHandler ref_bkptTable = BkptHandler {
-    isAutoBkptEnabled = \sess bkptLoc -> do 
-      bktpTable <- readIORef ref_bkptTable
-      return$ isBkptEnabled bktpTable bkptLoc
-
-  , handleBreakpoint = doBreakpoint ref_bkptTable 
-  }
-
-doBreakpoint :: IORef (BkptTable Module)-> Session -> [(Id,HValue)] -> BkptLocation Module -> String -> b -> IO b
-doBreakpoint ref_bkptTable s@(Session ref) values _ locMsg b = do
-         let (ids, hValues) = unzip values
-             names = map idName ids
-         ASSERT (length names == length hValues) return ()
-         let global_ids = map globaliseAndTidy ids
-         printScopeMsg locMsg global_ids
-         typed_ids  <- mapM instantiateIdType global_ids
-         hsc_env <- readIORef ref
-         let ictxt = hsc_IC hsc_env
-             rn_env   = ic_rn_local_env ictxt
-             type_env = ic_type_env ictxt
-             bound_names = map idName typed_ids
-             new_rn_env  = extendLocalRdrEnv rn_env bound_names
-		-- Remove any shadowed bindings from the type_env;
-		-- they are inaccessible but might, I suppose, cause 
-		-- a space leak if we leave them there
-             shadowed = [ n | name <- bound_names,
-                          let rdr_name = mkRdrUnqual (nameOccName name),
-                          Just n <- [lookupLocalRdrEnv rn_env rdr_name] ]
-             filtered_type_env = delListFromNameEnv type_env shadowed
-             new_type_env = extendTypeEnvWithIds filtered_type_env (typed_ids)
-             new_ic = ictxt { ic_rn_local_env = new_rn_env, 
-		  	      ic_type_env     = new_type_env }
-         writeIORef ref (hsc_env { hsc_IC = new_ic })
-         is_tty <- hIsTerminalDevice stdin
-         prel_mod <- GHC.findModule s prel_name Nothing
-         withExtendedLinkEnv (zip names hValues) $ 
-           startGHCi (interactiveLoop is_tty True) GHCiState{ 
-                              progname = "<interactive>",
-                              args     = [],
-                              prompt   = locMsg ++ "> ",
-                              session  = s,
-                              options  = [],
-                              bkptTable= ref_bkptTable,
-                              prelude  = prel_mod,
-			      topLevel = False }
-             `catchDyn` (\e -> case e of 
-                           StopChildSession -> evaluate$
-                                               throwDyn (ChildSessionStopped "")
-                           StopParentSession -> throwDyn StopParentSession
-           ) `finally` do
-             writeIORef ref hsc_env
-             putStrLn $ "Returning to normal execution..."
-         return b
+stepCmd :: String -> GHCi ()
+stepCmd []         = doContinue GHC.SingleStep
+stepCmd expression = do runStmt expression GHC.SingleStep; return ()
+
+traceCmd :: String -> GHCi ()
+traceCmd []         = doContinue GHC.RunAndLogSteps
+traceCmd expression = do runStmt expression GHC.RunAndLogSteps; return ()
+
+continueCmd :: String -> GHCi ()
+continueCmd = noArgs $ doContinue GHC.RunToCompletion
+
+doContinue :: SingleStep -> GHCi ()
+doContinue step = do 
+  session <- getSession
+  runResult <- io $ GHC.resume session step
+  afterRunStmt runResult
+  return ()
+
+abandonCmd :: String -> GHCi ()
+abandonCmd = noArgs $ do
+  s <- getSession
+  b <- io $ GHC.abandon s -- the prompt will change to indicate the new context
+  when (not b) $ io $ putStrLn "There is no computation running."
+  return ()
+
+deleteCmd :: String -> GHCi ()
+deleteCmd argLine = do
+   deleteSwitch $ words argLine
+   where
+   deleteSwitch :: [String] -> GHCi ()
+   deleteSwitch [] = 
+      io $ putStrLn "The delete command requires at least one argument."
+   -- delete all break points
+   deleteSwitch ("*":_rest) = discardActiveBreakPoints
+   deleteSwitch idents = do
+      mapM_ deleteOneBreak idents 
+      where
+      deleteOneBreak :: String -> GHCi ()
+      deleteOneBreak str
+         | all isDigit str = deleteBreak (read str)
+         | otherwise = return ()
+
+historyCmd :: String -> GHCi ()
+historyCmd arg
+  | null arg        = history 20
+  | all isDigit arg = history (read arg)
+  | otherwise       = io $ putStrLn "Syntax:  :history [num]"
+  where
+  history num = do
+    s <- getSession
+    resumes <- io $ GHC.getResumeContext s
+    case resumes of
+      [] -> io $ putStrLn "Not stopped at a breakpoint"
+      (r:rs) -> do
+        let hist = GHC.resumeHistory r
+            (took,rest) = splitAt num hist
+        spans <- mapM (io . GHC.getHistorySpan s) took
+        let nums = map (printf "-%-3d:") [(1::Int)..]
+        printForUser (vcat (zipWith (<+>) (map text nums) (map ppr spans)))
+        io $ putStrLn $ if null rest then "<end of history>" else "..."
+
+backCmd :: String -> GHCi ()
+backCmd = noArgs $ do
+  s <- getSession
+  (names, ix, span) <- io $ GHC.back s
+  printForUser $ ptext SLIT("Logged breakpoint at") <+> ppr span
+  mapM_ (showTypeOfName s) names
+   -- run the command set with ":set stop <cmd>"
+  st <- getGHCiState
+  runCommand (stop st)
+  return ()
+
+forwardCmd :: String -> GHCi ()
+forwardCmd = noArgs $ do
+  s <- getSession
+  (names, ix, span) <- io $ GHC.forward s
+  printForUser $ (if (ix == 0)
+                    then ptext SLIT("Stopped at")
+                    else ptext SLIT("Logged breakpoint at")) <+> ppr span
+  mapM_ (showTypeOfName s) names
+   -- run the command set with ":set stop <cmd>"
+  st <- getGHCiState
+  runCommand (stop st)
+  return ()
+
+-- handle the "break" command
+breakCmd :: String -> GHCi ()
+breakCmd argLine = do
+   session <- getSession
+   breakSwitch session $ words argLine
+
+breakSwitch :: Session -> [String] -> GHCi ()
+breakSwitch _session [] = do
+   io $ putStrLn "The break command requires at least one argument."
+breakSwitch session args@(arg1:rest) 
+   | looksLikeModuleName arg1 = do
+        mod <- wantInterpretedModule arg1
+        breakByModule session mod rest
+   | all isDigit arg1 = do
+        (toplevel, _) <- io $ GHC.getContext session 
+        case toplevel of
+           (mod : _) -> breakByModuleLine mod (read arg1) rest
+           [] -> do 
+              io $ putStrLn "Cannot find default module for breakpoint." 
+              io $ putStrLn "Perhaps no modules are loaded for debugging?"
+   | otherwise = do -- try parsing it as an identifier
+        wantNameFromInterpretedModule noCanDo arg1 $ \name -> do
+        let loc = GHC.srcSpanStart (GHC.nameSrcSpan name)
+        if GHC.isGoodSrcLoc loc
+               then findBreakAndSet (GHC.nameModule name) $ 
+                         findBreakByCoord (Just (GHC.srcLocFile loc))
+                                          (GHC.srcLocLine loc, 
+                                           GHC.srcLocCol loc)
+               else noCanDo name $ text "can't find its location: " <> ppr loc
+       where
+          noCanDo n why = printForUser $
+                text "cannot set breakpoint on " <> ppr n <> text ": " <> why
+
+breakByModule :: Session -> Module -> [String] -> GHCi () 
+breakByModule session mod args@(arg1:rest)
+   | all isDigit arg1 = do  -- looks like a line number
+        breakByModuleLine mod (read arg1) rest
+   | otherwise = io $ putStrLn "Invalid arguments to :break"
+
+breakByModuleLine :: Module -> Int -> [String] -> GHCi ()
+breakByModuleLine mod line args
+   | [] <- args = findBreakAndSet mod $ findBreakByLine line
+   | [col] <- args, all isDigit col =
+        findBreakAndSet mod $ findBreakByCoord Nothing (line, read col)
+   | otherwise = io $ putStrLn "Invalid arguments to :break"
+
+findBreakAndSet :: Module -> (TickArray -> Maybe (Int, SrcSpan)) -> GHCi ()
+findBreakAndSet mod lookupTickTree = do 
+   tickArray <- getTickArray mod
+   (breakArray, _) <- getModBreak mod
+   case lookupTickTree tickArray of 
+      Nothing  -> io $ putStrLn $ "No breakpoints found at that location."
+      Just (tick, span) -> do
+         success <- io $ setBreakFlag True breakArray tick 
+         session <- getSession
+         if success 
+            then do
+               (alreadySet, nm) <- 
+                     recordBreak $ BreakLocation
+                             { breakModule = mod
+                             , breakLoc = span
+                             , breakTick = tick
+                             }
+               printForUser $
+                  text "Breakpoint " <> ppr nm <>
+                  if alreadySet 
+                     then text " was already set at " <> ppr span
+                     else text " activated at " <> ppr span
+            else do
+            printForUser $ text "Breakpoint could not be activated at" 
+                                 <+> ppr span
+
+-- When a line number is specified, the current policy for choosing
+-- the best breakpoint is this:
+--    - the leftmost complete subexpression on the specified line, or
+--    - the leftmost subexpression starting on the specified line, or
+--    - the rightmost subexpression enclosing the specified line
+--
+findBreakByLine :: Int -> TickArray -> Maybe (BreakIndex,SrcSpan)
+findBreakByLine line arr
+  | not (inRange (bounds arr) line) = Nothing
+  | otherwise =
+    listToMaybe (sortBy leftmost_largest  complete)   `mplus`
+    listToMaybe (sortBy leftmost_smallest incomplete) `mplus`
+    listToMaybe (sortBy rightmost ticks)
+  where 
+        ticks = arr ! line
+
+        starts_here = [ tick | tick@(nm,span) <- ticks,
+                               GHC.srcSpanStartLine span == line ]
+
+        (complete,incomplete) = partition ends_here starts_here
+            where ends_here (nm,span) = GHC.srcSpanEndLine span == line
+
+findBreakByCoord :: Maybe FastString -> (Int,Int) -> TickArray
+                 -> Maybe (BreakIndex,SrcSpan)
+findBreakByCoord mb_file (line, col) arr
+  | not (inRange (bounds arr) line) = Nothing
+  | otherwise =
+    listToMaybe (sortBy rightmost contains)
   where 
-     printScopeMsg :: String -> [Id] -> IO ()
-     printScopeMsg location ids = do
-       unqual  <- GHC.getPrintUnqual s
-       printForUser stdout unqual $
-         text "Stopped at a breakpoint in " <> text (stripColumn location) <>
-         char '.' <+> text "Local bindings in scope:" $$
-         nest 2 (pprWithCommas showId ids)
-      where 
-           showId id = 
-                ppr (idName id) <+> dcolon <+> ppr (idType id) 
-           stripColumn = reverse . tail . dropWhile (/= ':') . reverse
-
--- | Give the Id a Global Name, and tidy its type
-     globaliseAndTidy :: Id -> Id
-     globaliseAndTidy id
-      = let tidied_type = tidyTopType$ idType id
-        in setIdType (globaliseId VanillaGlobal id) tidied_type
-
--- | Instantiate the tyVars with GHC.Base.Unknown
-     instantiateIdType :: Id -> IO Id
-     instantiateIdType id = do
-       instantiatedType <- instantiateTyVarsToUnknown s (idType id)
-       return$ setIdType id instantiatedType
+        ticks = arr ! line
+
+        -- the ticks that span this coordinate
+        contains = [ tick | tick@(nm,span) <- ticks, span `spans` (line,col),
+                            is_correct_file span ]
+
+        is_correct_file span
+                 | Just f <- mb_file = GHC.srcSpanFile span == f
+                 | otherwise         = True
+
+
+leftmost_smallest  (_,a) (_,b) = a `compare` b
+leftmost_largest   (_,a) (_,b) = (GHC.srcSpanStart a `compare` GHC.srcSpanStart b)
+                                `thenCmp`
+                                 (GHC.srcSpanEnd b `compare` GHC.srcSpanEnd a)
+rightmost (_,a) (_,b) = b `compare` a
+
+spans :: SrcSpan -> (Int,Int) -> Bool
+spans span (l,c) = GHC.srcSpanStart span <= loc && loc <= GHC.srcSpanEnd span
+   where loc = GHC.mkSrcLoc (GHC.srcSpanFile span) l c
+
+start_bold = BS.pack "\ESC[1m"
+end_bold   = BS.pack "\ESC[0m"
+
+listCmd :: String -> GHCi ()
+listCmd "" = do
+   mb_span <- getCurrentBreakSpan
+   case mb_span of
+      Nothing  -> printForUser $ text "not stopped at a breakpoint; nothing to list"
+      Just span -> io $ listAround span True
+listCmd str = list2 (words str)
+
+list2 [arg] | all isDigit arg = do
+    session <- getSession
+    (toplevel, _) <- io $ GHC.getContext session 
+    case toplevel of
+        [] -> io $ putStrLn "No module to list"
+        (mod : _) -> listModuleLine mod (read arg)
+list2 [arg1,arg2] | looksLikeModuleName arg1, all isDigit arg2 = do
+        mod <- wantInterpretedModule arg1
+        listModuleLine mod (read arg2)
+list2 [arg] = do
+        wantNameFromInterpretedModule noCanDo arg $ \name -> do
+        let loc = GHC.srcSpanStart (GHC.nameSrcSpan name)
+        if GHC.isGoodSrcLoc loc
+               then do
+                  tickArray <- getTickArray (GHC.nameModule name)
+                  let mb_span = findBreakByCoord (Just (GHC.srcLocFile loc))
+                                        (GHC.srcLocLine loc, GHC.srcLocCol loc)
+                                        tickArray
+                  case mb_span of
+                    Nothing       -> io $ listAround (GHC.srcLocSpan loc) False
+                    Just (_,span) -> io $ listAround span False
+               else
+                  noCanDo name $ text "can't find its location: " <>
+                                 ppr loc
+    where
+        noCanDo n why = printForUser $
+            text "cannot list source code for " <> ppr n <> text ": " <> why
+list2  _other = 
+        io $ putStrLn "syntax:  :list [<line> | <module> <line> | <identifier>]"
 
+listModuleLine :: Module -> Int -> GHCi ()
+listModuleLine modl line = do
+   session <- getSession
+   graph <- io (GHC.getModuleGraph session)
+   let this = filter ((== modl) . GHC.ms_mod) graph
+   case this of
+     [] -> panic "listModuleLine"
+     summ:_ -> do
+           let filename = fromJust (ml_hs_file (GHC.ms_location summ))
+               loc = GHC.mkSrcLoc (mkFastString (filename)) line 0
+           io $ listAround (GHC.srcLocSpan loc) False
+
+-- | list a section of a source file around a particular SrcSpan.
+-- If the highlight flag is True, also highlight the span using
+-- start_bold/end_bold.
+listAround span do_highlight = do
+      contents <- BS.readFile (unpackFS file)
+      let 
+          lines = BS.split '\n' contents
+          these_lines = take (line2 - line1 + 1 + pad_before + pad_after) $ 
+                        drop (line1 - 1 - pad_before) $ lines
+          fst_line = max 1 (line1 - pad_before)
+          line_nos = [ fst_line .. ]
+
+          highlighted | do_highlight = zipWith highlight line_nos these_lines
+                      | otherwise   = these_lines
+
+          bs_line_nos = [ BS.pack (show l ++ "  ") | l <- line_nos ]
+          prefixed = zipWith BS.append bs_line_nos highlighted
+      --
+      BS.putStrLn (BS.join (BS.pack "\n") prefixed)
+  where
+        file  = GHC.srcSpanFile span
+        line1 = GHC.srcSpanStartLine span
+        col1  = GHC.srcSpanStartCol span
+        line2 = GHC.srcSpanEndLine span
+        col2  = GHC.srcSpanEndCol span
+
+        pad_before | line1 == 1 = 0
+                   | otherwise  = 1
+        pad_after = 1
+
+        highlight no line
+          | no == line1 && no == line2
+          = let (a,r) = BS.splitAt col1 line
+                (b,c) = BS.splitAt (col2-col1) r
+            in
+            BS.concat [a,start_bold,b,end_bold,c]
+          | no == line1
+          = let (a,b) = BS.splitAt col1 line in
+            BS.concat [a, start_bold, b]
+          | no == line2
+          = let (a,b) = BS.splitAt col2 line in
+            BS.concat [a, end_bold, b]
+          | otherwise   = line
+
+-- --------------------------------------------------------------------------
+-- Tick arrays
+
+getTickArray :: Module -> GHCi TickArray
+getTickArray modl = do
+   st <- getGHCiState
+   let arrmap = tickarrays st
+   case lookupModuleEnv arrmap modl of
+      Just arr -> return arr
+      Nothing  -> do
+        (breakArray, ticks) <- getModBreak modl 
+        let arr = mkTickArray (assocs ticks)
+        setGHCiState st{tickarrays = extendModuleEnv arrmap modl arr}
+        return arr
+
+discardTickArrays :: GHCi ()
+discardTickArrays = do
+   st <- getGHCiState
+   setGHCiState st{tickarrays = emptyModuleEnv}
+
+mkTickArray :: [(BreakIndex,SrcSpan)] -> TickArray
+mkTickArray ticks
+  = accumArray (flip (:)) [] (1, max_line) 
+        [ (line, (nm,span)) | (nm,span) <- ticks,
+                              line <- srcSpanLines span ]
+    where
+        max_line = foldr max 0 (map GHC.srcSpanEndLine (map snd ticks))
+        srcSpanLines span = [ GHC.srcSpanStartLine span .. 
+                              GHC.srcSpanEndLine span ]
+
+lookupModule :: String -> GHCi Module
+lookupModule modName
+   = do session <- getSession 
+        io (GHC.findModule session (GHC.mkModuleName modName) Nothing)
+
+-- don't reset the counter back to zero?
+discardActiveBreakPoints :: GHCi ()
+discardActiveBreakPoints = do
+   st <- getGHCiState
+   mapM (turnOffBreak.snd) (breaks st)
+   setGHCiState $ st { breaks = [] }
+
+deleteBreak :: Int -> GHCi ()
+deleteBreak identity = do
+   st <- getGHCiState
+   let oldLocations    = breaks st
+       (this,rest)     = partition (\loc -> fst loc == identity) oldLocations
+   if null this 
+      then printForUser (text "Breakpoint" <+> ppr identity <+>
+                         text "does not exist")
+      else do
+           mapM (turnOffBreak.snd) this
+           setGHCiState $ st { breaks = rest }
+
+turnOffBreak loc = do
+  (arr, _) <- getModBreak (breakModule loc)
+  io $ setBreakFlag False arr (breakTick loc)
+
+getModBreak :: Module -> GHCi (GHC.BreakArray, Array Int SrcSpan)
+getModBreak mod = do
+   session <- getSession
+   Just mod_info <- io $ GHC.getModuleInfo session mod
+   let modBreaks  = GHC.modInfoModBreaks mod_info
+   let array      = GHC.modBreaks_flags modBreaks
+   let ticks      = GHC.modBreaks_locs  modBreaks
+   return (array, ticks)
+
+setBreakFlag :: Bool -> GHC.BreakArray -> Int -> IO Bool 
+setBreakFlag toggle array index
+   | toggle    = GHC.setBreakOn array index 
+   | otherwise = GHC.setBreakOff array index