Maybe? What Maybe? (rollback earlier dmenu change)

Commands.hs

@@ -102,9 +102,7 @@ runCommand :: [(String, X ())] -> X ()
 runCommand cl = do
   let m = commandMap cl
   choice <- dmenu (M.keys m)
-  case choice of
-    Just selection -> fromMaybe (return ()) (M.lookup selection m)
-    Nothing        -> return ()
+  fromMaybe (return ()) (M.lookup choice m)
 
 runCommand' :: String -> X ()
 runCommand' c = do

DirectoryPrompt.hs

@@ -18,8 +18,6 @@ module XMonadContrib.DirectoryPrompt (
                              directoryPrompt
                               ) where
 
-import Data.Maybe(fromMaybe)
-
 import XMonad
 import XMonadContrib.XPrompt
 import XMonadContrib.Dmenu ( runProcessWithInput )
@@ -36,7 +34,7 @@ directoryPrompt :: XPConfig -> String -> (String -> X ()) -> X ()
 directoryPrompt c prom job = mkXPrompt (Dir prom) c getDirCompl job
 
 getDirCompl :: String -> IO [String]
-getDirCompl s = (filter notboring . lines . fromMaybe "") `fmap`
+getDirCompl s = (filter notboring . lines) `fmap`
                 runProcessWithInput "/bin/bash" [] ("compgen -A directory " ++ s ++ "\n")
 
 notboring :: String -> Bool

Dmenu.hs

@@ -22,7 +22,6 @@ module XMonadContrib.Dmenu (
 import XMonad
 import qualified StackSet as W
 import qualified Data.Map as M
-import System.Exit
 import System.Process
 import System.IO
 import Control.Monad.State
@@ -36,7 +35,7 @@ import Control.Monad.State
 
 -- | Returns Just output if the command succeeded, and Nothing if it didn't.
 -- This corresponds to dmenu's notion of exit code 1 for a cancelled invocation.
-runProcessWithInput :: FilePath -> [String] -> String -> IO (Maybe String)
+runProcessWithInput :: FilePath -> [String] -> String -> IO String
 runProcessWithInput cmd args input = do
     (pin, pout, perr, ph) <- runInteractiveProcess cmd args Nothing Nothing
     hPutStr pin input
@@ -45,21 +44,20 @@ runProcessWithInput cmd args input = do
     when (output==output) $ return ()
     hClose pout
     hClose perr
-    exitCode <- waitForProcess ph
-    case exitCode of
-      ExitSuccess   -> return (Just output)
-      ExitFailure _ -> return Nothing
+    waitForProcess ph
+    return output
 
 -- | Starts dmenu on the current screen. Requires this patch to dmenu:
 -- <http://www.jcreigh.com/dmenu/dmenu-3.2-xinerama.patch>
-dmenuXinerama :: [String] -> X (Maybe String)
+dmenuXinerama :: [String] -> X String
 dmenuXinerama opts = do
     curscreen <- (fromIntegral . W.screen . W.current) `liftM` gets windowset :: X Int
     io $ runProcessWithInput "dmenu" ["-xs", show (curscreen+1)] (unlines opts)
 
-dmenu :: [String] -> X (Maybe String)
+dmenu :: [String] -> X String
 dmenu opts = io $ runProcessWithInput "dmenu" [] (unlines opts)
 
 dmenuMap :: M.Map String a -> X (Maybe a)
-dmenuMap selectionMap =
-  dmenu (M.keys selectionMap) >>= return . maybe Nothing (flip M.lookup selectionMap)
+dmenuMap selectionMap = do
+  selection <- dmenu (M.keys selectionMap)
+  return $ M.lookup selection selectionMap

ShellPrompt.hs

@@ -25,7 +25,6 @@ import XMonadContrib.Dmenu
 
 import Control.Monad
 import Data.List
-import Data.Maybe
 import System.Directory
 import System.IO
 import System.Environment
@@ -58,7 +57,7 @@ shellPrompt c = mkXPrompt Shell c getShellCompl spawn
 getShellCompl :: String -> IO [String]
 getShellCompl s 
     | s /= "" && last s /= ' ' = do
-  f <- fmap (lines . fromMaybe "") $ runProcessWithInput "/bin/bash" [] ("compgen -A file " ++ s ++ "\n")
+  f <- fmap lines $ runProcessWithInput "/bin/bash" [] ("compgen -A file " ++ s ++ "\n")
   c <- commandCompletionFunction s
   hPutStrLn stdout s
   return . map escape . sort . nub $ f ++ c

WorkspaceDir.hs

@@ -68,10 +68,8 @@ workspaceDir :: LayoutClass l a => String -> l a
 workspaceDir s = ModifiedLayout (WorkspaceDir s)
 
 scd :: String -> X ()
-scd x = do x' <- io (runProcessWithInput "bash" [] ("echo -n " ++ x) `catch` \_ -> return Nothing)
-           case x' of
-             Just newDir -> catchIO $ setCurrentDirectory newDir
-             Nothing     -> return ()
+scd x = do x' <- io (runProcessWithInput "bash" [] ("echo -n " ++ x) `catch` \_ -> return x)
+           catchIO $ setCurrentDirectory x'
 
 changeDir :: XPConfig -> X ()
 changeDir c = directoryPrompt c "Set working directory: " (sendMessage . Chdir)