def stringList = [ "java", "perl", "python", "ruby", "c#", "cobol",
                   "groovy", "jython", "smalltalk", "prolog", "m", "yacc" ];
stringList.eachWithIndex() { obj, i -> println " ${i}: ${obj}" };

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'
    }
}