feat: limited support of lamdas in Series.apply

bigframes/core/compile/scalar_op_compiler.py

@@ -658,10 +658,6 @@ def isin_op_impl(x: ibis_types.Value, op: ops.IsInOp):
 
 @scalar_op_compiler.register_unary_op(ops.RemoteFunctionOp, pass_op=True)
 def remote_function_op_impl(x: ibis_types.Value, op: ops.RemoteFunctionOp):
-    if not hasattr(op.func, "bigframes_remote_function"):
-        raise TypeError(
-            f"only a bigframes remote function is supported as a callable. {constants.FEEDBACK_LINK}"
-        )
     x_transformed = op.func(x)
     if not op.apply_on_null:
         x_transformed = ibis.case().when(x.isnull(), x).else_(x_transformed).end()

tests/system/small/test_series.py

@@ -2997,3 +2997,32 @@ def test_series_iter(
         scalars_df_index["int64_too"], scalars_pandas_df_index["int64_too"]
     ):
         assert bf_i == pd_i
+
+
+@pytest.mark.parametrize(
+    ("lambda_",),
+    [
+        pytest.param(lambda x: x * x + x + 1),
+        pytest.param(
+            lambda x: f"I got {x}",
+            marks=pytest.mark.xfail(
+                raises=AttributeError,
+            ),
+        ),
+    ],
+    ids=[
+        "lamda_arithmatic",
+        "lambda_arbitrary",
+    ],
+)
+def test_apply_lambda(scalars_dfs, lambda_):
+    scalars_df, scalars_pandas_df = scalars_dfs
+
+    bf_col = scalars_df["int64_col"]
+    bf_result = bf_col.apply(lambda_).to_pandas()
+
+    pd_col = scalars_pandas_df["int64_col"]
+    pd_result = pd_col.apply(lambda_)
+
+    # ignore dtype check, which are Int64 and object respectively
+    assert_series_equal(bf_result, pd_result, check_dtype=False)