Toni,

correct me if I'm wrong: your suggestion looks very similar to what you do in Haskell where the syntax without parenthesis and commas is allowed by the fact that in this language every function officially takes only one parameter, while the functions that apparently accept more than one argument are actually curried functions. You can find more explanations about this syntax, for example, here:

http://learnyouahaskell.com/higher-order-functions

Despite I like this syntax because it allows to eliminate some punctuation making the code often (but not always) more readable I also see 2 main problems with it:

1. It implies a larger use of curried functions and I am not sure that the biggest part of Drools users will feel comfortable with them.
2. It will bring our syntax even farther from the one that will be available in Java 8.