DouKaku?

def crossProduct( params ){

    def result = []

    switch(params.size()){
    case 1:
        // 何もしない
        break;
    case 2:
        params[0].each{ item1 ->
            params[1].each{ item2 ->
                result << ([] + item1) + ([] + item2)
            }
        }
        break;
    default:
        result = crossProduct( [crossProduct(params[0..1])] + params[2..-1])
        break;
    }

    result
}


crossProduct([[1,2,3,4], ["a", "b", "c"], ["あ", "い"]]).each{
    println it
}
crossProduct([[1,2,3,4], "abc"]).each{
    println it
}