SQL queries on Kotlin data class with Apache Spark

spark_sql.kt

package org.cakesolutions.spark.sql

import org.apache.spark.SparkConf
import org.apache.spark.api.java.JavaSparkContext
import org.apache.spark.sql.DataFrame
import org.apache.spark.sql.Row
import org.apache.spark.sql.SQLContext
import org.cakesolutions.spark.awaitEnter
import java.io.Serializable


fun main(args: Array<String>) = awaitEnter {


    val conf = SparkConf().setMaster("local").setAppName("SQL")
    val sc = JavaSparkContext(conf)
    val sqlCtx = SQLContext(sc)

    val happyPeopleRDD = sc.parallelize(listOf(
            HappyPerson("Mario", "Colombian Coffee"),
            HappyPerson("Freddy", "Cheap Coffee"),
            HappyPerson("Ben", "Tea"),
            HappyPerson("Vicente", "Tequila"),
            HappyPerson("Hideo", "Sake")
    ))
    val happyPeopleDF = sqlCtx.applySchema(happyPeopleRDD, javaClass<HappyPerson>())

    //with like VB!!!
    with(happyPeopleDF) {
        registerTempTable("happy_people")
        cache()
        // this is happyPeopleDF
        info(this)
    }
    val coffeeDrinkers = sqlCtx.sql("""
        select name from happy_people where favouriteBeverage like '%Coffee%'
    """)

    coffeeDrinkers.collectAsList().forEach { row -> println(row.string[0]) }
}

data class HappyPerson(var name: String? = null,
                       var favouriteBeverage: String? = null) : Serializable

private fun info(df: DataFrame) {
    df.show()
    df.printSchema()
}

//DSLy stuff like KotlinPrimavera
val Row.string: GetFieldToken<String>
    get () {
        return GetFieldToken { getString(it) }
    }

class GetFieldToken<T>(val extract: (Int) -> T) {
    fun get(index: Int) = extract(index)
}

//Wait for a new line to finish the program
fun awaitEnter(body: () -> Unit) {
    body()
    val scanner = Scanner(System.`in`)
    scanner.nextLine()
    println("Bye!")
}