Hello, We have merged a new Antlr4 based DRL parser in the drools main branch. It's not enabled by default, so it doesn't affect users now.
The new parser has been focused on backward compatibility and existing unit tests are all green with it. However, at this point, we can take an opportunity to "slim down DRL syntax" in order to improve the future maintainability of drools. PROPOSAL is - Drop or modify some DRL syntax, which cause maintenance cost and/or ambiguity and/or are less useful. - Introduce LanguageLevelOption.DRL10 for the new syntax. Enabled when configured. It is handled by the new parser. - Announce "deprecate" for the dropped syntax, so that users can migrate to DRL10. - At some point in the future, make LanguageLevelOption.DRL10 default. (Still keep DRL6 and the old parser as a transition period) - When we consider the new parser is mature, we will remove DRL6 and the old parser Further details and candidates syntax to drop are written in this docs. https://docs.google.com/document/d/1Ibmj-koAMbeaungHuFeQtw2zD03YJcNJkJ-kdN8ugks/edit?usp=sharing Feel free to add comments on the docs. Discussing this on the thread is also great. Thanks! Toshiya
