Yet another try to support Stack.

Language/Haskell/GhcMod/CabalHelper.hs

@@ -20,6 +20,7 @@ module Language.Haskell.GhcMod.CabalHelper
   ( getComponents
   , getGhcMergedPkgOptions
   , getCabalPackageDbStack
+  , getStackPackageDbStack
   , getCustomPkgDbStack
   , prepareCabalHelper
   )
@@ -43,6 +44,7 @@ import Language.Haskell.GhcMod.PathsAndFiles
 import Language.Haskell.GhcMod.Logging
 import Language.Haskell.GhcMod.Output
 import System.FilePath
+import System.Directory (findExecutable)
 import Prelude hiding ((.))
 
 import Paths_ghc_mod as GhcMod
@@ -132,6 +134,16 @@ getCustomPkgDbStack = do
     mCusPkgDbFile <- liftIO . (traverse readFile <=< findCustomPackageDbFile) . cradleRootDir =<< cradle
     return $ parseCustomPackageDb <$> mCusPkgDbFile
 
+getStackPackageDbStack :: IOish m => m [GhcPkgDb]
+getStackPackageDbStack = do
+    mstack <- liftIO $ findExecutable "stack"
+    case mstack of
+      Nothing -> return []
+      Just stack -> do
+        snapshotDb <- liftIO $ readProcess stack ["path", "--snapshot-pkg-db"] ""
+        localDb <- liftIO $ readProcess stack ["path", "--local-pkg-db"] ""
+        return $ map (PackageDb . takeWhile (/='\n')) [snapshotDb, localDb]
+
 withCabal :: (IOish m, GmEnv m, GmLog m) => m a -> m a
 withCabal action = do
     crdl <- cradle

Language/Haskell/GhcMod/Cradle.hs

@@ -29,7 +29,7 @@ findCradle = findCradle' =<< getCurrentDirectory
 
 findCradle' :: FilePath -> IO Cradle
 findCradle' dir = run $ do
-    (cabalCradle dir `mplus`  sandboxCradle dir `mplus` plainCradle dir)
+    (stackCradle dir `mplus` cabalCradle dir `mplus` sandboxCradle dir `mplus` plainCradle dir)
  where run a = fillTempDir =<< (fromJust <$> runMaybeT a)
 
 findSpecCradle :: FilePath -> IO Cradle
@@ -67,6 +67,22 @@ cabalCradle wdir = do
       , cradleCabalFile  = Just cabalFile
       }
 
+stackCradle :: FilePath -> MaybeT IO Cradle
+stackCradle wdir = do
+    cabalFile <- MaybeT $ findCabalFile wdir
+
+    let cabalDir = takeDirectory cabalFile
+
+    stackConfigFile <- MaybeT $ findStackConfigFile cabalDir
+
+    return Cradle {
+        cradleProjectType = StackProject
+      , cradleCurrentDir = wdir
+      , cradleRootDir    = cabalDir
+      , cradleTempDir    = error "tmpDir"
+      , cradleCabalFile  = Just cabalFile
+      }
+
 sandboxCradle :: FilePath -> MaybeT IO Cradle
 sandboxCradle wdir = do
     sbDir <- MaybeT $ findCabalSandboxDir wdir

Language/Haskell/GhcMod/GhcPkg.hs

@@ -71,6 +71,8 @@ getPackageDbStack = do
         return $ [GlobalDb, db]
     CabalProject ->
         getCabalPackageDbStack
+    StackProject ->
+        getStackPackageDbStack
   return $ fromMaybe stack mCusPkgStack
 
 getPackageCachePaths :: IOish m => FilePath -> GhcModT m [FilePath]

Language/Haskell/GhcMod/PathsAndFiles.hs

@@ -71,6 +71,9 @@ findCabalFile dir = do
    appendDir :: DirPath -> [FileName] -> [FilePath]
    appendDir d fs = (d </>) `map` fs
 
+findStackConfigFile :: FilePath -> IO (Maybe FilePath)
+findStackConfigFile dir = mightExist (dir </> "stack.yaml")
+
 -- | Get path to sandbox config file
 getSandboxDb :: FilePath
              -- ^ Path to the cabal package root directory (containing the

Language/Haskell/GhcMod/Target.hs

@@ -149,6 +149,7 @@ targetGhcOptions crdl sefnmn = do
 
     case cradleProjectType crdl of
       CabalProject -> cabalOpts crdl
+      StackProject -> stackOpts crdl
       _ -> sandboxOpts crdl
  where
    zipMap f l = l `zip` (f `map` l)
@@ -264,8 +265,17 @@ packageGhcOptions = do
     crdl <- cradle
     case cradleProjectType crdl of
       CabalProject -> getGhcMergedPkgOptions
+      StackProject -> stackOpts crdl
       _ -> sandboxOpts crdl
 
+stackOpts :: MonadIO m => Cradle -> m [String]
+stackOpts crdl = do
+    pkgDbStack <- liftIO getStackPackageDbStack
+    let pkgOpts = ghcDbStackOpts pkgDbStack
+    return $ ["-i" ++ d | d <- [wdir,rdir]] ++ pkgOpts ++ ["-Wall"]
+  where
+    (wdir, rdir) = (cradleCurrentDir crdl, cradleRootDir crdl)
+
 -- also works for plain projects!
 sandboxOpts :: MonadIO m => Cradle -> m [String]
 sandboxOpts crdl = do

Language/Haskell/GhcMod/Types.hs

@@ -121,7 +121,7 @@ defaultOptions = Options {
 
 ----------------------------------------------------------------
 
-data ProjectType = CabalProject | SandboxProject | PlainProject
+data ProjectType = CabalProject | SandboxProject | PlainProject | StackProject
                  deriving (Eq, Show)
 
 -- | The environment where this library is used.