Github user myui commented on a diff in the pull request:
https://github.com/apache/incubator-hivemall/pull/163#discussion_r215564184
--- Diff: core/src/main/java/hivemall/ftvec/text/OkapiBM25UDF.java ---
@@ -0,0 +1,167 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package hivemall.ftvec.text;
+
+import hivemall.UDFWithOptions;
+import org.apache.commons.cli.CommandLine;
+import org.apache.commons.cli.Options;
+import org.apache.hadoop.hive.ql.exec.Description;
+import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
+import org.apache.hadoop.hive.ql.metadata.Hive;
+import org.apache.hadoop.hive.ql.metadata.HiveException;
+import hivemall.utils.hadoop.HiveUtils;
+import org.apache.hadoop.hive.ql.udf.UDFType;
+import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
+import
org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector;
+import
org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
+import
org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorUtils;
+import org.apache.hadoop.io.DoubleWritable;
+
+import javax.annotation.Nonnull;
+import java.util.Arrays;
+
+@Description(name = "okapi_bm25",
+ value = "_FUNC_(double tf_word, int dl, double avgdl, int N, int n
[, const string options]) - Return an Okapi BM25 score in float")
+//TODO: What does stateful mean?
--- End diff --
https://hive.apache.org/javadocs/r1.2.2/api/org/apache/hadoop/hive/ql/udf/UDFType.html#stateful()
So, it's okey `stateful = false`. Please remove this comment.
---
