Pietro Martinelli
kotlin

The beautiness of Kotlin - Episode 0

I like very much the fluency which you can define a micro-DSL with when you’re lucky enough to write Kotlin code: e.g., let’s implement a very very simple DSL to express distances:

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fun main() {
    val marathon = 42.km + 195.m + 30.cm
    println("Marathon = ${marathon}")
}

// Extension properties: Java/C# developer, can you exploit any similar feature? ;-)
val Int.km: Distance
	get() = Distance(this.toDouble() * 1000)

val Int.m: Distance
	get() = Distance(this.toDouble())

val Int.cm: Distance
	get() = Distance(this.toDouble() / 100)

data class Distance(val m: Double) {
  // Operator overloading made simple and OO-friendly:
  //  nothing to do with C# similar, static-method based feature!
    operator fun plus(that: Distance) = Distance(this.m + that.m)
}

You can run the previous code here.