I have added https://issues.apache.org/jira/browse/ZEST-36 which proposes to use Java 8 Predicate class for Constraints, instead of our own Constraint class. I don't think we need the Constraint class anymore...
My GutFeeling(tm) also indicates that there is a use of java.util.function.Function for return value transformations, but perhaps that is not useful in practice. It might get too messy... Cheers -- Niclas Hedhman, Software Developer http://zest.apache.org - New Energy for Java
