gistfile1.java

sealed case class Agent(name: String)
sealed case class Machine(agent: Agent, parent: Machine)

trait Applicable[I, O] {
    def apply(a: Applicable[I, I]): Applicable[I, O] = {
        val outer_apply: Function1[I, O] = apply

        new Applicable[I, O] {
            def apply(obj: I): O = outer_apply(a(obj))
        }
    }

    def apply(obj: I): O
}

object agent extends Applicable[Machine, Agent] {
    def apply(obj: Machine) = obj.agent
}

object parent extends Applicable[Machine, Machine] {
    def apply(obj: Machine) = obj.parent
}


object DSL2 {
    def main(args: Array[String]): Unit = {
        val m1 = Machine(Agent("agent1"), null)
        val m2 = Machine(Agent("agent2"), m1)
        val m3 = Machine(Agent("agent3"), m2)

        val selector = agent(parent(parent))
        println("Name of agent: " + selector(m3).name)

        println("Name of agent of m3: " + agent(m3).name)
    }
}

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