Initial support for adding body from signature

src/GHCMod.hs

@@ -39,6 +39,7 @@ usage =    progVersion
         ++ "\t ghc-mod info" ++ ghcOptHelp ++ "<HaskellFile> <module> <expression>\n"
         ++ "\t ghc-mod type" ++ ghcOptHelp ++ "<HaskellFile> <module> <line-no> <column-no>\n"
         ++ "\t ghc-mod split" ++ ghcOptHelp ++ "<HaskellFile> <module> <line-no> <column-no>\n"
+        ++ "\t ghc-mod sig" ++ ghcOptHelp ++ "<HaskellFile> <module> <line-no> <column-no>\n"
         ++ "\t ghc-mod find <symbol>\n"
         ++ "\t ghc-mod lint [-h opt] <HaskellFile>\n"
         ++ "\t ghc-mod root\n"
@@ -121,6 +122,7 @@ 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)
       "split"   -> nArgs 4 $ splitVar opt cradle cmdArg1 (read cmdArg3) (read cmdArg4)
+      "sig"     -> nArgs 4 $ fillSig opt cradle cmdArg1 (read cmdArg3) (read cmdArg4)
       "find"    -> runGhcMod opt $ nArgs 1 $ findSymbol cmdArg1
       "lint"    -> nArgs 1 withFile (lintSyntax opt) cmdArg1
       "root"    -> rootInfo opt cradle

src/GHCModi.hs

@@ -145,6 +145,7 @@ loop opt set mvar = do
         "info"   -> toGhcMod $ showInfo opt set arg
         "type"   -> toGhcMod $ showType opt set arg
         "split"  -> toGhcMod $ doSplit  opt set arg
+        "sig"    -> toGhcMod $ doSig    opt set arg
         "boot"   -> bootIt set
         "browse" -> browseIt set arg
         "quit"   -> return ("quit", False, set)
@@ -265,6 +266,16 @@ doSplit opt set fileArg  = do
     ret <- splits opt file (read line) (read column)
     return (ret, True, set')
 
+doSig :: Options
+      -> Set FilePath
+      -> FilePath
+      -> Ghc (String, Bool, Set FilePath)
+doSig opt set fileArg  = do
+    let [file, line, column] = words fileArg
+    set' <- newFileSet set file
+    ret <- sig opt file (read line) (read column)
+    return (ret, True, set')
+
 ----------------------------------------------------------------
 
 bootIt :: Set FilePath