A Type-safe Monad that combines Node and List<Node> written in Groovy++

SomeNode.groovy

package org.korat.ast

class SomeNode {

    List<Node> data

    String getText()  { data[0].text  }
    String getType()  { data[0].type  }
    List<Node> getChild() { data[0].child }

    SomeNode getUnresolvedProperty(String name) {
        return data[0].getUnresolvedProperty(name)
    }

    SomeNode getAt(int i) {
        return new SomeNode(data: [data[i]])
    }

    String toString() {
        return "#" + data[0].toString()
    }
}