ghc-mod root does not need a file.

Language/Haskell/GhcMod/Debug.hs

@@ -1,4 +1,4 @@
-module Language.Haskell.GhcMod.Debug (debugInfo, debug, rootInfo, root) where
+module Language.Haskell.GhcMod.Debug (debugInfo, debug, rootInfo) where
 
 import Control.Applicative ((<$>))
 import Control.Exception.IOChoice ((||>))
@@ -62,13 +62,5 @@ debug opt cradle fileName = do
 -- | Obtaining root information.
 rootInfo :: Options
           -> Cradle
-          -> FilePath   -- ^ A target file.
           -> IO String
-rootInfo opt cradle fileName = withGHC fileName (root opt cradle fileName)
+rootInfo opt cradle = return $ convert opt $ cradleRootDir cradle
-
--- | Obtaining root information.
-root :: Options
-      -> Cradle
-      -> FilePath     -- ^ A target file.
-      -> Ghc String
-root _ cradle _ = return $ cradleRootDir cradle ++ "\n"

src/GHCMod.hs

@@ -34,7 +34,7 @@ usage =    "ghc-mod version " ++ showVersion version ++ "\n"
         ++ "\t ghc-mod info" ++ ghcOptHelp ++ "<HaskellFile> <module> <expression>\n"
         ++ "\t ghc-mod type" ++ ghcOptHelp ++ "<HaskellFile> <module> <line-no> <column-no>\n"
         ++ "\t ghc-mod lint [-h opt] <HaskellFile>\n"
-        ++ "\t ghc-mod root <HaskellFile>\n"
+        ++ "\t ghc-mod root\n"
         ++ "\t ghc-mod doc <module>\n"
         ++ "\t ghc-mod boot\n"
         ++ "\t ghc-mod help\n"
@@ -116,7 +116,7 @@ main = flip E.catches handlers $ do
       "info"   -> nArgs 3 infoExpr opt cradle cmdArg1 cmdArg3
       "type"   -> nArgs 4 $ typeExpr opt cradle cmdArg1 (read cmdArg3) (read cmdArg4)
       "lint"   -> nArgs 1 withFile (lintSyntax opt) cmdArg1
-      "root"   -> nArgs 1 $ rootInfo opt cradle cmdArg1
+      "root"   -> rootInfo opt cradle
       "doc"    -> nArgs 1 $ packageDoc opt cradle cmdArg1
       "boot"   -> do
          mods  <- listModules opt cradle