//modified to work with Kotlin 1.0.x
private val keywords = arrayOf("foo", "bar", "spam")
private val pattern = keywords.joinToString(prefix = "(?i)", separator = "|")
private val rx = pattern.toRegex()

fun findKeyword(content: String): MutableList<String> { 
    var result = mutableListOf<String>()
    rx.findAll(content).forEach { result.add(it.value) }
    return result
}

fun main(args: Array<String>) { 
    println(findKeyword("Some spam and a lot of bar"));
    println(arrayOf("foo", "bar", "spam").joinToString(prefix = "(?i)", separator = "|").toRegex())
}