feat: Diff packages

commands/util/diff.py

@@ -0,0 +1,22 @@
+from typing import List
+
+
+def pkg_diff(target: List[str], actual: List[str]) -> tuple[List[str], List[str]]:
+    """Compute a diff between target packages and installed packages
+
+    Args:
+        target: The target packages
+        actual: The actually installed packages
+
+    Returns:
+        A tuple with first the missing (not installed) packages
+        and second the extraneous (to be uninstalled) packages
+    """
+    for i, pkg in enumerate(actual):
+        try:
+            idx = target.index(pkg)
+            target.pop(idx)
+            actual.pop(i)
+        except Exception:
+            pass
+    return (target, actual)