refactor `Git.withWorkingTree`

1 files changed, 15 insertions, 0 deletions

diff --git a/app/Git.hs b/app/Git.hs
new file mode 100644
index 0000000..57fffdc
--- /dev/null
+++ b/app/Git.hs
@@ -0,0 +1,15 @@
+module Git (withWorkingTree) where
+
+import Control.Exception (finally)
+import Data.Text (Text)
+import Process (proc, sh_)
+import System.Directory (createDirectoryIfMissing)
+import System.FilePath (dropTrailingPathSeparator, takeDirectory)
+
+-- | Runs an IO-action within a working tree.
+withWorkingTree :: FilePath -> Text -> IO a -> IO a
+withWorkingTree path hash action = do
+  createDirectoryIfMissing True (takeDirectory (dropTrailingPathSeparator path))
+  sh_ $ proc "git worktree add --quiet --detach % %" path hash
+  action `finally` do
+    sh_ $ proc "git worktree remove --force %" path