More with expressive Time things and Kotlin

TimeStuff.kt

enum class TimeUnit(val name: String, val divisorFromNanos: Long, val precision: Int) {
    Seconds : TimeUnit("seconds", 1000000000, 2)
    Millis : TimeUnit("millis", 1000000, 0)
    Micros : TimeUnit("micros", 1000, 0)
    Nanos : TimeUnit("nanos", 1, 0)

    fun toHumanReadable(nanoTime: Long): String = "%.${precision}f ${name}".format(nanoTime.toFloat() / divisorFromNanos.toFloat())
}

class Duration(val duration: Long, val units: TimeUnit, private val durationInNanos: Long = duration * units.divisorFromNanos) : Comparable<Duration> {
    override fun toString(): String = units.toHumanReadable(durationInNanos)
    override fun equals(other: Any?): Boolean = other != null && other is Duration && this.durationInNanos == other.durationInNanos
    override fun compareTo(other: Duration): Int = this.durationInNanos.compareTo(other.durationInNanos)
    override fun hashCode(): Int = (durationInNanos % 0xFFFFFFFF).toInt()
    fun to(units: TimeUnit): Duration = Duration(durationInNanos / units.divisorFromNanos, units, durationInNanos)
    fun elapsedSince(other: Duration): Duration = Duration(durationInNanos - other.durationInNanos, units)
}

val Int.seconds: Duration  get() { return Duration(this.toLong(), TimeUnit.Seconds)  }
val Int.nanos: Duration  get() { return Duration(this.toLong(), TimeUnit.Nanos) }
val Int.micros: Duration  get() { return Duration(this.toLong(), TimeUnit.Micros) }
val Int.millis: Duration  get() { return Duration(this.toLong(), TimeUnit.Millis) }
val Long.seconds: Duration get() { return Duration(this, TimeUnit.Seconds) }
val Long.nanos: Duration  get() { return Duration(this, TimeUnit.Nanos) }
val Long.micros: Duration  get() { return Duration(this, TimeUnit.Micros) }
val Long.millis: Duration  get() { return Duration(this, TimeUnit.Millis) }

fun measure(name: String = "timer", desiredUnits: TimeUnit, foo: () -> Unit): Duration {
    val startTime = System.nanoTime().nanos
    foo()
    val endTime = System.nanoTime().nanos
    return endTime elapsedSince startTime to desiredUnits
}

// NOW TEST WITH:

fun main(args: Array<String>) {
    val elapsed = measure("hello printer", TimeUnit.Nanos) { for (i in 1..1000) println("hello") }
    println(elapsed.to(TimeUnit.Seconds))
    println(elapsed to TimeUnit.Millis)
    println(elapsed to TimeUnit.Micros)
    println(elapsed to TimeUnit.Nanos)
    println(elapsed to TimeUnit.Millis to TimeUnit.Seconds to TimeUnit.Micros to TimeUnit.Nanos) // lossless
    /* output:
        0.03 seconds
        29 millis
        28903 micros
        28903000 nanos
        28903000 nanos
    */
    println(50.seconds)
    println(50.millis to TimeUnit.Seconds)
    println(1.nanos to TimeUnit.Seconds to TimeUnit.Nanos) // lossless
    /* output:
        50.00 seconds
        0.05 seconds
        1 nanos
    */
}