"info" and "type" can display it even if the source file is broken.

GHCMod.hs

@@ -27,8 +27,8 @@ usage =    "ghc-mod version 0.5.0\n"
         ++ "\t ghc-mod [-l] lang\n"
         ++ "\t ghc-mod [-l] browse <module> [<module> ...]\n"
         ++ "\t ghc-mod check <HaskellFile>\n"
-        ++ "\t ghc-mod type <HaskellFile> <expression>\n"
-        ++ "\t ghc-mod info <HaskellFile> <expression>\n"
+        ++ "\t ghc-mod type <HaskellFile> <module> <expression>\n"
+        ++ "\t ghc-mod info <HaskellFile> <module> <expression>\n"
         ++ "\t ghc-mod [-h opt] lint <HaskellFile>\n"
         ++ "\t ghc-mod boot\n"
         ++ "\t ghc-mod help\n"
@@ -75,8 +75,8 @@ main = flip catches handlers $ do
       "browse" -> concat <$> mapM (browseModule opt) (tail cmdArg)
       "list"   -> listModules opt
       "check"  -> withFile (checkSyntax opt) (safelist cmdArg 1)
-      "type"   -> withFile (typeExpr opt (safelist cmdArg 2)) (safelist cmdArg 1)
-      "info"   -> withFile (infoExpr opt (safelist cmdArg 2)) (safelist cmdArg 1)
+      "type"   -> withFile (typeExpr opt (safelist cmdArg 2) (safelist cmdArg 3)) (safelist cmdArg 1)
+      "info"   -> withFile (infoExpr opt (safelist cmdArg 2) (safelist cmdArg 3)) (safelist cmdArg 1)
       "lint"   -> withFile (lintSyntax opt)  (safelist cmdArg 1)
       "lang"   -> listLanguages opt
       "boot"   -> do

Info.hs

@@ -9,35 +9,47 @@ import Types
 import NameSet
 import HscTypes
 import Data.List
+import Control.Exception
+
+type Expression = String
+type ModuleString = String
 
 ----------------------------------------------------------------
 
-typeExpr :: Options -> String -> String -> IO String
-typeExpr _ expr file = (++ "\n") <$> typeOf file expr
+typeExpr :: Options -> ModuleString -> Expression -> FilePath -> IO String
+typeExpr _ modstr expr file = (++ "\n") <$> typeOf file modstr expr
 
-typeOf :: String -> String -> IO String
-typeOf fileName expr = withGHC $ do
-    initSession []
-    setTargetFile fileName
-    load LoadAllTargets
-    setContextFromTarget
-    pretty <$> exprType expr
+typeOf :: FilePath -> ModuleString-> Expression -> IO String
+typeOf fileName modstr expr = withGHC $ valid `gcatch` invalid
   where
+    valid = makeTypeOf LoadAllTargets
+    invalid = constE invalid0
+    invalid0 = makeTypeOf $ LoadDependenciesOf (mkModuleName modstr)
+    makeTypeOf x = do
+        initSession ["-w"]
+        setTargetFile fileName
+        loadWithLogger (\_ -> return ()) x
+        setContextFromTarget
+        pretty <$> exprType expr
     pretty = showSDocForUser neverQualify . pprTypeForUser False
 
 ----------------------------------------------------------------
 
-infoExpr :: Options -> String -> String -> IO String
-infoExpr _ expr file = (++ "\n") <$> info file expr
+infoExpr :: Options -> ModuleString -> Expression -> FilePath -> IO String
+infoExpr _ modstr expr file = (++ "\n") <$> info file modstr expr
 
-info :: String -> String -> IO String
-info fileName expr = withGHC $ do
-    initSession []
-    setTargetFile fileName
-    load LoadAllTargets
-    setContextFromTarget
-    infoThing expr
+info :: FilePath -> ModuleString -> FilePath -> IO String
+info fileName modstr expr = withGHC $ valid `gcatch` invalid
   where
+    valid = makeInfo LoadAllTargets
+    invalid = constE invalid0
+    invalid0 = makeInfo $ LoadDependenciesOf (mkModuleName modstr)
+    makeInfo x = do
+        initSession ["-w"]
+        setTargetFile fileName
+        loadWithLogger (\_ -> return ()) x
+        setContextFromTarget
+        infoThing expr
     -- ghc/InteractiveUI.hs
     infoThing str = do
         names <- parseName str
@@ -68,5 +80,15 @@ pprInfo pefas (thing, fixity, insts)
 setContextFromTarget :: Ghc ()
 setContextFromTarget = do
     ms <- depanal [] False
-    mdl <- findModule (ms_mod_name (head ms)) Nothing
-    setContext [mdl] []
+    mdls <- mapM toModule ms
+    setContext (catMaybes mdls) []
+ where
+   toModule ms = lookupMod `gcatch` nothing
+     where
+       lookupMod = lookupModule (ms_mod_name ms) Nothing >>= return . Just
+       nothing = constE $ return Nothing
+
+----------------------------------------------------------------
+
+constE :: a -> (SomeException -> a)
+constE func = \_ -> func

elisp/ghc-info.el

@@ -14,35 +14,53 @@
   (interactive "P")
   (if (not (ghc-which ghc-module-command))
       (message "%s not found" ghc-module-command)
-    (let* ((expr0 (thing-at-point 'symbol))
-	   (expr (if ask (ghc-read-expression expr0) expr0))
-	   (cdir default-directory)
-	   (file (buffer-name)))
-      (with-temp-buffer
-	(cd cdir)
-	(call-process ghc-module-command nil t nil "type" file expr)
-	(message (buffer-substring (point-min) (1- (point-max))))))))
+    (let ((modname (ghc-find-module-name)))
+      (if (not modname)
+	  (message "module should be specified")
+	(ghc-show-type0 ask modname)))))
+
+(defun ghc-show-type0 (ask modname)
+  (let* ((expr0 (thing-at-point 'symbol))
+	 (expr (if ask (ghc-read-expression expr0) expr0))
+	 (cdir default-directory)
+	 (file (buffer-name)))
+    (with-temp-buffer
+      (cd cdir)
+      (call-process ghc-module-command nil t nil "type" file modname expr)
+      (message (buffer-substring (point-min) (1- (point-max)))))))
 
 (defun ghc-show-info (&optional ask)
   (interactive "P")
   (if (not (ghc-which ghc-module-command))
       (message "%s not found" ghc-module-command)
-    (let* ((expr0 (thing-at-point 'symbol))
-	   (expr (if ask (ghc-read-expression expr0) expr0))
-	   (cdir default-directory)
-	   (file (buffer-name))
-	   (buf (get-buffer-create ghc-error-buffer-name)))
-      (with-current-buffer buf
-        (erase-buffer)
-	(insert
-	 (with-temp-buffer
-	   (cd cdir)
-	   (call-process ghc-module-command nil t nil "info" file expr)
-	   (buffer-substring (point-min) (1- (point-max))))))
-      (display-buffer buf))))
+    (let ((modname (ghc-find-module-name)))
+      (if (not modname)
+	  (message "module should be specified")
+	(ghc-show-info0 ask modname)))))
+
+(defun ghc-show-info0 (ask modname)
+  (let* ((expr0 (thing-at-point 'symbol))
+	 (expr (if ask (ghc-read-expression expr0) expr0))
+	 (cdir default-directory)
+	 (file (buffer-name))
+	 (buf (get-buffer-create ghc-error-buffer-name)))
+    (with-current-buffer buf
+      (erase-buffer)
+      (insert
+       (with-temp-buffer
+	 (cd cdir)
+	 (call-process ghc-module-command nil t nil "info" file modname expr)
+	 (buffer-substring (point-min) (1- (point-max))))))
+    (display-buffer buf)))
 
 (defun ghc-read-expression (default)
   (let ((prompt (format "Expression (%s): " default)))
     (read-string prompt default nil)))
 
+(defun ghc-find-module-name ()
+  (save-excursion
+    (goto-char (point-min))
+    (if (re-search-forward "^module[ ]+\\([^ ]+\\)" nil t)
+	(match-string-no-properties 1))))
+
 (provide 'ghc-info)