Alright, so writing XML really put Uncle Bob in rage. Of course, he is right: XML should be limited to machine to machine exchanges and should never be forced down the throats of human beings, let alone geeks of all sorts. The natural consequence of that is I decided to start looking into adding DSL support to NxBRE, as writing RuleML is really not a fun task.
In my wildest dreams it will remotely be as good as the DSL support of Drools (including a code-assist driven full text editor). The harsh reality of (a busy) life will probably limit the scope of this addition to NxBRE but should anyway give the rules authors a better way of expressing themselves.
To build the grammar I decided to use ANTLR and its great companion tool: ANTLRWorks. I came to this choice thanks to Martin Fowler's current exploratory works on DSLs.
ANTLRWorks has proven really useful in this endeavor: the immediate testing and debugging of the grammar is complemented by a tree representation of the exploration graph that simplifies the detection of syntax goofs and other mistakes.
I have committed the embryo of a rules grammar in the trunk Misc directory. Capturing is still to implement. Then a translation table of plain English format blocks to RuleML atoms will have to be added.
ETA is obviously N/A ;-)