factor out `getDirectoryContentsRecursive` function in GHCup.Utils.Prelude

lib/GHCup/Utils/Prelude.hs

@@ -340,31 +340,31 @@ copyDirectoryRecursive srcDir destDir = do
     -- parent directories. The list is generated lazily so is not well defined if
     -- the source directory structure changes before the list is used.
     --
-    getDirectoryContentsRecursive :: FilePath -> IO [FilePath]
-    getDirectoryContentsRecursive topdir = recurseDirectories [""]
+getDirectoryContentsRecursive :: FilePath -> IO [FilePath]
+getDirectoryContentsRecursive topdir = recurseDirectories [""]
+  where
+    recurseDirectories :: [FilePath] -> IO [FilePath]
+    recurseDirectories []         = return []
+    recurseDirectories (dir:dirs) = unsafeInterleaveIO $ do
+      (files, dirs') <- collect [] [] =<< getDirectoryContents (topdir </> dir)
+      files' <- recurseDirectories (dirs' ++ dirs)
+      return (files ++ files')
+
       where
-        recurseDirectories :: [FilePath] -> IO [FilePath]
-        recurseDirectories []         = return []
-        recurseDirectories (dir:dirs) = unsafeInterleaveIO $ do
-          (files, dirs') <- collect [] [] =<< getDirectoryContents (topdir </> dir)
-          files' <- recurseDirectories (dirs' ++ dirs)
-          return (files ++ files')
-
-          where
-            collect files dirs' []              = return (reverse files
-                                                         ,reverse dirs')
-            collect files dirs' (entry:entries) | ignore entry
-                                                = collect files dirs' entries
-            collect files dirs' (entry:entries) = do
-              let dirEntry = dir </> entry
-              isDirectory <- doesDirectoryExist (topdir </> dirEntry)
-              if isDirectory
-                then collect files (dirEntry:dirs') entries
-                else collect (dirEntry:files) dirs' entries
-
-            ignore ['.']      = True
-            ignore ['.', '.'] = True
-            ignore _          = False
+        collect files dirs' []              = return (reverse files
+                                                     ,reverse dirs')
+        collect files dirs' (entry:entries) | ignore entry
+                                            = collect files dirs' entries
+        collect files dirs' (entry:entries) = do
+          let dirEntry = dir </> entry
+          isDirectory <- doesDirectoryExist (topdir </> dirEntry)
+          if isDirectory
+            then collect files (dirEntry:dirs') entries
+            else collect (dirEntry:files) dirs' entries
+
+        ignore ['.']      = True
+        ignore ['.', '.'] = True
+        ignore _          = False
 
 -- https://github.com/haskell/directory/issues/110
 -- https://github.com/haskell/directory/issues/96