Adding a ":clear" clear-screen command to GHCi

[porges]

I have written a (hopeful) patch for this. I say hopeful because I'm not sure if it even compiles (I don't have the space to compile GHC at the moment...).

Anyway if this could be confirmed to work and then incorporated that would be nice :)

@@ -119,6 +119,7 @@
   ("browse!",   keepGoing (browseCmd True),	Nothing, completeModule),
   ("cd",    	keepGoing changeDirectory,	Just filenameWordBreakChars, completeFilename),
   ("check",	keepGoing checkModule,		Nothing, completeHomeModule),
+  ("clear", keepGoing clearScreen, Nothing, completeNone),
   ("continue",  keepGoing continueCmd,          Nothing, completeNone),
   ("cmd",       keepGoing cmdCmd,               Nothing, completeIdentifier),
   ("ctags",	keepGoing createCTagsFileCmd, 	Just filenameWordBreakChars, completeFilename),
@@ -200,6 +201,7 @@
  "   :browse[!] [[*]<mod>]       display the names defined by module <mod>\n" ++
  "                               (!: more details; *: all top-level names)\n" ++
  "   :cd <dir>                   change directory to <dir>\n" ++
+ "   :clear                      clear the screen\n" ++
  "   :cmd <expr>                 run the commands returned by <expr>::IO String\n" ++
  "   :ctags [<file>]             create tags file for Vi (default: \"tags\")\n" ++
  "   :def <cmd> <expr>           define a command :<cmd>\n" ++
@@ -936,6 +938,15 @@
   prev_context <- GHC.getContext
   ok <- trySuccess $ GHC.load LoadAllTargets
   afterLoad ok False prev_context
+  
+clearScreen :: String -> GHCi ()
+clearScreen _ = do
+  let cmd = case os of			
+    "windows" -> Just "cls"
+    "linux" -> Just "clear"
+    _ -> Nothing
+  didnt_work <- maybe (return True) shellEscape cmd
+  when didnt_work (io (putStrLn ("Error: unsupported operating system for command 'clear'. Please report a bug.")))
 
 changeDirectory :: String -> GHCi ()
 changeDirectory "" = do

[judah]

You can use ghci macros to do this:

 http://haskell.org/haskellwiki/GHC/GHCi

Add the following line to your ~/.ghci file:

:def clear \_ -> return $ ":!clear"

[simonmar]

I don't think this is something we need to add to GHCi. e.g. just hitting Ctrl-L does it for me.