[Browse] Option to show symbol parents

E.g. Nothing is a constructor of Maybe, so it has
parent Maybe.

This is useful for completion, e.g. with `(..)` imports

Language/Haskell/GhcMod/Boot.hs

@@ -7,12 +7,13 @@ import Language.Haskell.GhcMod.Flag
 import Language.Haskell.GhcMod.Lang
 import Language.Haskell.GhcMod.Monad
 import Language.Haskell.GhcMod.Modules
+import Language.Haskell.GhcMod.Types (defaultBrowseOpts)
 
 -- | Printing necessary information for front-end booting.
 boot :: IOish m => GhcModT m String
 boot = concat <$> sequence ms
   where
-    ms = [modules False, languages, flags, concat <$> mapM (browse (BrowseOpts False False False)) preBrowsedModules]
+    ms = [modules False, languages, flags, concat <$> mapM (browse defaultBrowseOpts) preBrowsedModules]
 
 preBrowsedModules :: [String]
 preBrowsedModules = [

Language/Haskell/GhcMod/Browse.hs

@@ -11,6 +11,7 @@ import Data.List
 import Data.Maybe
 import FastString
 import GHC
+import HscTypes
 import qualified GHC as G
 import Language.Haskell.GhcMod.Convert
 import Language.Haskell.GhcMod.Doc (showPage, styleUnqualified)
@@ -96,14 +97,20 @@ showExport opt minfo e = do
     mqualified = (G.moduleNameString (G.moduleName $ G.nameModule e) ++ ".") `justIf` optBrowseQualified opt
     mtype :: m (Maybe String)
     mtype
-      | optBrowseDetailed opt = do
+      | optBrowseDetailed opt || optBrowseParents opt = do
         tyInfo <- G.modInfoLookupName minfo e
         -- If nothing found, load dependent module and lookup global
         tyResult <- maybe (inOtherModule e) (return . Just) tyInfo
         dflag <- G.getSessionDynFlags
-        return $ do
-          typeName <- tyResult >>= showThing dflag
-          (" :: " ++ typeName) `justIf` optBrowseDetailed opt
+        let sig = do
+                    typeName <- tyResult >>= showThing dflag
+                    (" :: " ++ typeName) `justIf` optBrowseDetailed opt
+        let parent = do
+                    thing <- fmap getOccString $ tyResult >>= tyThingParent_maybe
+                    (" ; " ++ thing) `justIf` optBrowseParents opt
+        return $ case concat $ catMaybes [sig, parent] of
+                    [] -> Nothing
+                    x  -> Just x
       | otherwise = return Nothing
     formatOp nm
       | null nm    = error "formatOp"

Language/Haskell/GhcMod/Types.hs

@@ -388,13 +388,15 @@ data BrowseOpts = BrowseOpts {
         -- ^ If 'True', "browseWith" also returns operators.
       , optBrowseDetailed       :: Bool
         -- ^ If 'True', "browseWith" also returns types.
+      , optBrowseParents        :: Bool
+        -- ^ If 'True', "browseWith" also returns parents.
       , optBrowseQualified      :: Bool
         -- ^ If 'True', "browseWith" will return fully qualified name
     } deriving (Show)
 
 -- | Default "BrowseOpts" instance
 defaultBrowseOpts :: BrowseOpts
-defaultBrowseOpts = BrowseOpts False False False
+defaultBrowseOpts = BrowseOpts False False False False
 
 mkLabel ''GhcModCaches
 mkLabel ''GhcModState

src/GHCMod/Options/Commands.hs

@@ -255,6 +255,10 @@ browseArgSpec = CmdBrowse
             $$  long "detailed"
             <=> short 'd'
             <=> help "Print symbols with accompanying signature"
+        <*> switch
+            $$  long "parents"
+            <=> short 'p'
+            <=> help "Print symbols parents"
         <*> switch
             $$  long "qualified"
             <=> short 'q'