- release notes and docs

drools-docs/src/modules/ROOT/pages/language-reference/_language-level.adoc

@@ -0,0 +1,146 @@
+////
+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.
+////
+
+[id='language-level_drl-rules']
+
+= Language Level
+
+Language Level is a feature that allows you to specify the version of the DRL (Drools Rule Language) syntax you want to use.
+
+Supported language levels are:
+
+* DRL6 (default)
+* DRL10
+
+Some old language levels are deprecated and will be removed in the future:
+
+* DRL5
+* DRL6_STRICT
+
+DRL6 is compatible with the previous Drools versions, while DRL10 introduces some changes to reduce ambiguity.
+
+Language Level can be specified by kmodule.xml or system property. Note that the configuration should be effective when rules are built.
+
+.kmodule.xml example
+[source,xml]
+----
+<kmodule xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xmlns="http://www.drools.org/xsd/kmodule">
+  <configuration>
+    <property key="drools.lang.level" value="DRL10"/>
+  </configuration>
+</kmodule>
+----
+
+.System property example
+[source,java]
+----
+    System.setProperty("drools.lang.level", "DRL10");
+----
+
+== DRL10
+
+DRL10 has been added, which is handled by the new parser based on ANTLR4. DRL10 introduces the following changes mainly to reduce ambiguity:
+
+* Require a prefix `##` to custom operators
+.DRL6
+[source]
+----
+   Person(addresses supersetOf $alice.addresses)
+----
+
+.DRL10
+[source]
+----
+   Person(addresses ##supersetOf $alice.addresses)
+----
+
+The custom operator's implementation Java code wouldn't need to be changed.
+
+* Drop half constraint syntax
+
+.DRL6
+[source]
+----
+   Person(age > 10 && < 20)
+----
+
+.DRL10 (also valid in DRL6)
+[source]
+----
+   Person(age > 10 && age < 20)
+----
+
+* Drop double ampersand as infix and
+
+.DRL6
+[source]
+----
+   ( Person(age == 10)
+      &&
+     Person(age == 20) )
+----
+
+.DRL10 (also valid in DRL6)
+[source]
+----
+   ( Person(age == 10)
+      and
+     Person(age == 20) )
+----
+
+`&&` in a constraint will remain supported. For example, `Person(age == 10 && age == 20)` is valid in DRL6 and DRL10.
+
+* Drop double pipe as infix or
+
+.DRL6
+[source]
+----
+   ( Person(age == 10)
+      ||
+     Person(age == 20) )
+----
+
+.DRL10 (also valid in DRL6)
+[source]
+----
+   ( Person(age == 10)
+      or
+     Person(age == 20) )
+----
+
+`||` in a constraint will remain supported. For example, `Person(age == 10 || age == 20)` is valid in DRL6 and DRL10.
+
+* Drop annotation inside LHS pattern
+
+.DRL6
+[source]
+----
+       ( Double()
+          or @Annot1 String()
+          or @Annot2 Integer() )
+----
+
+There is no equivalent expression in DRL10.
+
+Annotation in other places will remain supported. For example, `Person(name == "Mario") @watch(*)` is valid in DRL6 and DRL10.
+
+Those syntaxes are deprecated and will be removed in the future. Warnings are logged when the deprecated syntax is used in DRL6.
+
+Warnings are logged when the deprecated syntax is used in DRL6. The warning logs can be suppressed by the log level of `org.drools.drl.parser.lang.ParserHelper`.

drools-docs/src/modules/ROOT/pages/language-reference/index.adoc

@@ -29,3 +29,5 @@ include::_drl-rules.adoc[leveloffset=+1]
 include::_performance-tuning-drl-ref.adoc[leveloffset=+2]
 
 include::_XLSDecisionTable-section.adoc[leveloffset=+1]
+
+include::_language-level.adoc[leveloffset=+1]

drools-docs/src/modules/ROOT/pages/release-notes/_release-notes-10.1.adoc

@@ -0,0 +1,35 @@
+////
+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.
+////
+
+== 10.1.0 release notes
+
+=== Language Level DRL10
+New language level DRL10 has been added. DRL10 is handled by the new parser based on ANTLR4. The default language level is still DRL6.
+
+DRL10 introduces the following changes mainly to reduce ambiguity:
+
+* Require a prefix '##' to custom operators
+* Drop half constraint syntax
+* Drop double ampersand as infix and
+* Drop double pipe as infix or
+* Drop annotation inside LHS pattern
+
+Those syntaxes are deprecated and will be removed in the future. Warnings are logged when the deprecated syntax is used in DRL6.
+
+You can refer xref:language-reference/index.adoc#language-level_drl-rules[Language Level] for details.

drools-docs/src/modules/ROOT/pages/release-notes/index.adoc

@@ -30,6 +30,8 @@ This chapter contains the release notes for the {PRODUCT} 10-series.
 
 For the release notes of the _previous releases_, you can refer to the {PRODUCT} documentation of link:https://docs.drools.org/8.44.0.Final/drools-docs/drools/release-notes/index.html[version 8].
 
+include::_release-notes-10.1.adoc[leveloffset=0]
+
 include::_release-notes-10.0.adoc[leveloffset=0]
 
 == Drools 10-series release notes