support multi package cabal projects

Author: Avi-D-coder

README.md

@@ -1,5 +1,5 @@
 # implicit-hie
 ```bash
 cd your-stack-or-cabal-package
-gen-hie > hie.yaml
+gen-hie
 ```

app/Main.hs

@@ -9,19 +9,44 @@ import qualified Data.Text.IO as T
 import Hie.Cabal.Parser
 import Hie.Yaml
 import System.Directory
+import System.Directory.Internal
 import System.FilePath.Posix
 
 main :: IO ()
 main = do
-  files <- listDirectory =<< getCurrentDirectory
-  let path = filter ((".cabal" ==) . takeExtension) files
-      sOrC =
+  pwd <- getCurrentDirectory
+  files <- listDirectory pwd
+  cfs <- cabalFiles pwd
+  let sOrC =
         if  | any ((".stack-work" ==) . takeFileName) files -> stackHieYaml
             | any (("dist-newstyle" ==) . takeFileName) files -> cabalHieYaml
             | any (("stack.yaml" ==) . takeFileName) files -> stackHieYaml
             | otherwise -> cabalHieYaml
-  when (null path) $ error "No .cabal file found!\n You may need to run stack build."
-  file <- T.readFile $ head path
-  case parseOnly parsePackage file of
-    Right r -> T.putStr $ sOrC r
-    _ -> error "Could not parse *.cabal file"
+      gen f = do
+        f' <- T.readFile f
+        case parseOnly parsePackage f' of
+          Right r -> do
+            let hiePath = fst (splitFileName f) </> "hie.yaml"
+            T.writeFile hiePath $ sOrC r
+            pure ("wrote " <> hiePath)
+          _ -> pure $ "Could not parse " <> f
+  when (null cfs) $ error $
+    "No .cabal files found under"
+      <> pwd
+      <> "\n You may need to run stack build."
+  mapM_ (putStrLn <=< gen) cfs
+
+cabalFiles :: FilePath -> IO [FilePath]
+cabalFiles f = do
+  fs <- listDirectory f
+  case filter ((".cabal" ==) . takeExtension) fs of
+    h : _ -> pure [f </> h]
+    _ ->
+      fmap concat . mapM cabalFiles
+        =<< filterM
+          (fmap (fileTypeIsDirectory . fileTypeFromMetadata) . getFileMetadata)
+          ( map (f </>) $
+              filter
+                (`notElem` [".git", "dist", "dist-newstyle", ".stack-work"])
+                fs
+          )