parsePhoneNumber.kt

// https://medium.com/@garnop/safe-concise-text-parsing-with-regex-destructuring-in-kotlin-b8f77ef1e30c

fun parsePhoneNumber(input: String): PhoneNumber {
    val invalids = input.filterNot { it in '0'..'9' || it == '-' }
    require(invalids.isEmpty()) { "Input $input has invalid characters : $invalids" }
    val (areaCode, prefix, lineNumber) = input.split("-").map(String::toInt)
	return PhoneNumber(areaCode, prefix, lineNumber)
}

fun main(args: Array<String>) {
	val input = 
	require(parsePhoneNumber("888-888-8888") == PhoneNumber(888, 888, 8888))
}

data class PhoneNumber(
    val areaCode: Int,
    val prefix: Int,
    val lineNumber: Int
)