class CaseCategory {
    static boolean isCase(Closure casePredicate, Object switchParameter) {
        casePredicate.call switchParameter
    }
}
 
use (CaseCategory) {
    switch (param) {
        case { it % 2 == 0 } : return 'even'
        case { it % 3 == 0 } : return 'threeven'
        case { 0 < it }      : return 'positive'
        default              : return 'negative'
    }
}