FizzBuzz, without modulo, imperative and functional

FizzBuzz.scala

// Imperative

var fizzbuzz = 15
var fizz = 3
var buzz = 5
for(i <- 1 to 100) {
  val s = 
    if (i == fizzbuzz) { 
      fizz = fizzbuzz + 3
      buzz = fizzbuzz + 5 
      fizzbuzz += 15
      "FizzBuzz"
    } else if (i == fizz) {
      fizz += 3 
      "Fizz"
    } else if (i == buzz) {
      buzz += 5
      "Buzz"
    } else i
        
  println(s)
}

// Functional (blows the heap for big i (c.f. scala stream impl)

def unfold[S, A](s:S)(f:S => (S, A)):Stream[A] = {
  val (ns, a) = f(s)
  Stream.cons(a, unfold(ns)(f))
}
  
val fb = unfold((1, (15, 3, 5))){
  case ((i, s@(fizzbuzz, fizz, buzz))) =>
    val (ns, a) = i match { 
      case `fizzbuzz` =>
        ((fizzbuzz + 15, fizzbuzz + 3, fizzbuzz + 5), "FizzBuzz")
      case `fizz`     => 
        ((fizzbuzz, fizz + 3, buzz), "Fizz")
      case `buzz`     => 
        ((fizzbuzz, fizz, buzz + 5), "Buzz")
      case _        => 
        (s, i)
    }
    ((i + 1, ns), a)
}

fb take(100) foreach println