diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
new file mode 100644
index 0000000..9cd602b
--- /dev/null
+++ b/.github/workflows/build.yml
@@ -0,0 +1,27 @@
+name: Build Matrix
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+  workflow_dispatch:
+jobs:
+  generate-matrix:
+    runs-on: ubuntu-latest
+    outputs:
+      matrix: ${{ steps.set-matrix.outputs.matrix }}
+    steps:
+      - uses: actions/checkout@v5
+        with:
+          fetch-depth: 0
+
+      - name: Get changed files
+        id: changed-files
+        uses: tj-actions/changed-files@v47
+
+      - name: List all changed files
+        env:
+          ALL_CHANGED_FILES: ${{ steps.changed-files.outputs.all_changed_files }}
+        run: |
+          for file in ${ALL_CHANGED_FILES}; do
+            echo "$file was changed"
+          done
diff --git a/cabal-extract/Main.hs b/cabal-extract/Main.hs
index 36cbfb5..6d9a716 100644
--- a/cabal-extract/Main.hs
+++ b/cabal-extract/Main.hs
@@ -34,7 +34,6 @@ import System.Directory
     getCurrentDirectory,
     listDirectory,
   )
-import System.Environment (getArgs)
 import System.FilePath
   ( takeExtension,
     takeFileName,
@@ -152,15 +151,11 @@ removeExternalDeps = map removeExt
         }
 
 main :: IO ()
-main = do
-  args <- getArgs
-
-  allCabals <- getCurrentDirectory >>= findCabalFiles >>= extractFlatDepTree
-  allTargets <- mapM findCabalFiles args >>= extractFlatDepTree . concat
-
-  filter (\c -> ciName c `elem` map ciName allTargets) allCabals
-    & encode
-    & BL.putStrLn
+main =
+  getCurrentDirectory
+    >>= findCabalFiles
+    >>= extractFlatDepTree
+    >>= BL.putStrLn . encode
   where
     extractFlatDepTree x =
       mapM (readGenericPackageDescription Verbosity.deafening) x