feat(third_party/bazel): Check in rules_haskell from Tweag

third_party/bazel/rules_haskell/haskell/private/mode.bzl

@@ -0,0 +1,12 @@
+"""Compilation modes."""
+
+def is_profiling_enabled(hs):
+    """Check whether profiling mode is enabled.
+
+    Args:
+      hs: Haskell context.
+
+    Returns:
+      bool: True if the mode is enabled, False otherwise.
+    """
+    return hs.mode == "dbg"