FizzBuzz with Pattern Matching in Kotlin

Seeing FizzBuzz implementation in Clojure with clojure.core.match makes me wondering if Kotlin has the same pattern matching capabilities or at least some resemblance in the way of doing matching.

Unfortunately Kotlin when still sort for that. Fortunately we still can achieve it with some misuse of equals function!

The idea is to create a Pattern class that will take the parameter in when and return if it's true or not.


// FizzBuzz ModResult -> ModResult( number % 3, number % 5)

class ModResult(val a: Int, val b: Int) {
    override fun equals(other: Any?): Boolean {
        if (other is Pattern) {
            return other.match(this)
        }
        return other == this
    }
}

class FizzPattern : Pattern {
    override fun match(modResult: ModResult): Boolean = modResult.a == 0
}

...Buzz Pattern, FizzBuzz pattern

And after that you can just using it with when:

(1..100).forEach { number ->
        val result: Any = ModResult(number % 3, number % 5)
        when (result) {
            fizzBuzz -> println("FizzBuzz")
            fizz -> println("Fizz")
            buzz -> println("Buzz")
            else -> println(number)
        }
    }

Voila, FizzBuzz with pattern matching-ish in Kotlin! You can find the full code in this Github File

That's all for now, until next time. Cao ~ 👋